U.S. patent application number 15/184922 was filed with the patent office on 2017-05-11 for methods and apparatus to identify eye coverings for vision.
The applicant listed for this patent is NexisVision, Inc.. Invention is credited to Yair Alster, Matt Clarke, Eugene de Juan, JR., Brian Levy, K. Angela Macfarlane, Cary J. Reich, Ashley Tuan.
Application Number | 20170131566 15/184922 |
Document ID | / |
Family ID | 46024780 |
Filed Date | 2017-05-11 |
United States Patent
Application |
20170131566 |
Kind Code |
A1 |
de Juan, JR.; Eugene ; et
al. |
May 11, 2017 |
METHODS AND APPARATUS TO IDENTIFY EYE COVERINGS FOR VISION
Abstract
Methods and apparatus can fit coverings to treat eyes. The
treated eye may comprise a natural eye, for example an eye treated
for refractive error with a contact lens, or an eye having an
epithelial defect of the eye, such as an eye ablated with PRK
refractive surgery. In many embodiments, the covering can be
identified so as to provide improved flow of tear liquid under the
covering. The covering can be identified based on an inner corneal
curvature and an outer corneal curvature and one or more of a
limbus sag height or a conjunctival sag height. The covering may
form a chamber when placed on the eye to pump tear liquid under at
least a portion of the covering. The covering may comprise an outer
portion with rigidity to resist movement on the cornea and an inner
portion to contact the cornea and provide an environment for
epithelial regeneration. The covering may comprise a material
having high oxygen permeability, for example silicone, with a
wettable coating disposed on at least an upper surface of the
coating.
Inventors: |
de Juan, JR.; Eugene; (San
Francisco, CA) ; Alster; Yair; (Palo Alto, CA)
; Reich; Cary J.; (Los Gatos, CA) ; Tuan;
Ashley; (Mountain View, CA) ; Macfarlane; K.
Angela; (Woodside, CA) ; Clarke; Matt;
(Mountain View, CA) ; Levy; Brian; (New York,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NexisVision, Inc. |
Menlo Park |
CA |
US |
|
|
Family ID: |
46024780 |
Appl. No.: |
15/184922 |
Filed: |
June 16, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13885135 |
Oct 21, 2013 |
9395558 |
|
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PCT/US2011/057755 |
Oct 25, 2011 |
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15184922 |
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61406504 |
Oct 25, 2010 |
|
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61480231 |
Apr 28, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 3/0041 20130101;
A61F 9/00804 20130101; A61F 9/00806 20130101; A61B 3/0025 20130101;
A61B 3/107 20130101; A61F 2009/00859 20130101; G02C 2202/16
20130101; A61F 2009/00872 20130101; A61B 3/1005 20130101; G02C
7/049 20130101; A61F 9/04 20130101; G02C 7/04 20130101; G02C 7/027
20130101; G02C 7/048 20130101; G02C 7/047 20130101; A61B 3/1015
20130101; A61B 3/18 20130101 |
International
Class: |
G02C 7/04 20060101
G02C007/04; A61F 9/04 20060101 A61F009/04; A61B 3/00 20060101
A61B003/00; A61B 3/107 20060101 A61B003/107; A61B 3/10 20060101
A61B003/10 |
Claims
1. A method of treating an eye of a patient, the eye having a
cornea, the method comprising: measuring the eye to determine data
of the eye corresponding to an inner ablated portion of the cornea
and an outer unablated portion of the cornea away from the ablated
portion; and identifying a covering of a plurality of coverings to
treat the eye based on the data of the eye and an array of data
corresponding to the plurality of therapeutic coverings.
2. The method of claim 1 further comprising placing the covering on
the eye.
3. The method of claim 1 wherein the covering comprises an inner
covering portion and an outer covering portion, the inner covering
portion contacting the inner ablated portion of the cornea and an
outer covering portion contacting an unablated portion when placed
on the cornea and wherein the inner covering portion prior to
placement on the eye has a covering curvature no more than a
curvature of the ablated portion of the cornea and wherein the
outer covering portion comprises a curvature prior to placement on
the eye no more than the outer unablated portion of the cornea and
wherein the covering resists movement of the inner portion when
placed on the eye.
4. The method of claim 3 wherein the outer portion of the covering
extends to a conjunctiva of the eye and couples to the sclera of
the eye to resist movement of the inner portion.
5. The method of claim 3 wherein the inner portion of the covering
prior to placement comprises a substantially uniform thickness and
an amount of curvature corresponding to less optical power than the
optical power of the ablated portion of the cornea, the amount of
curvature of the inner portion prior to placement within a range
from about -1D to about -3D relative to the ablated portion of the
cornea.
6. The method of claim 5 wherein the inner covering deflects at
least about 1D so as to conform at least partially to the ablation
and promote smooth epithelial regeneration and vision.
7. The method of claim 3 wherein the inner portion of the covering
comprises an amount of rigidity within a range from about 1E-4 to
about 5E-4 (Pa*m 3) and the outer portion of the covering comprises
an outer amount of rigidity less than the amount of rigidity of the
inner portion.
8. The method of claim 1 wherein measuring the eye comprises
determining a conjunctiva sag height, the conjunctiva sag height
corresponding to a portion of a conjunctiva of the eye at a radial
location away from a reference axis of the eye and wherein the
covering comprises a covering sag height at a covering location
corresponding to the radial location of the portion of conjunctiva
and wherein the covering is identified such that the covering sag
height is greater than the conjunctiva sag height.
9. The method of claim 8 wherein the covering is deflected at the
covering location when the covering is placed on the eye.
10. The method of claim 8 wherein the conjunctiva sag height is
determined based on a measurement of a sclera of the eye
corresponding to the radial location.
11. The method of claim 1 wherein measuring the eye comprises
determining a limbus sag height, the limbus sag height
corresponding to a portion of a limbus of the eye at a radial
location away from a reference axis of the eye and wherein the
covering comprises a covering sag height at a covering location
corresponding to the radial location of the portion of the limbus
and wherein the covering is identified such that the covering sag
height is no more than the limbus sag height.
12. The method of claim 11 wherein the covering is deflected a
first amount at a first covering location corresponding to a
portion of the conjunctiva when the covering is placed on the eye
and wherein the covering is deflected a second amount at a second
covering location corresponding to a portion of the limbus when the
covering is placed on the eye, the second amount less than the
first amount such that pressure from the covering to the limbus is
inhibited.
13. The method of claim 1 wherein the covering comprises an inner
portion having a hydrogel layer extending along a lower surface to
contact the ablated portion and the unablated portion of the cornea
and wherein the covering comprises an outer portion comprising a
sticky tacky surface to contact the conjunctiva and inhibit
movement of the covering when the inner portion contacts the
cornea.
14. An apparatus to treat an eye, the apparatus comprising: an
input to receive data of the eye, the data of the eye corresponding
to an inner ablated portion of the cornea and an outer unablated
portion of the cornea away from the ablated portion; an output; and
at least one processor coupled to the input and the output, the at
least one processor comprising at least one computer readable
memory, the at least one computer readable memory having
instructions to store an array of data corresponding to a plurality
of therapeutic coverings and instructions to identify a covering of
the plurality based on the array and the data of the eye
corresponding to the inner ablated portion and the outer
portion.
15. The apparatus of claim 14 wherein the instructions are
configured to identify a covering having an inner portion
comprising a lower surface curvature flatter than the inner ablated
portion of the eye to inhibit one or more irregularities of the
epithelium.
16. The apparatus of claim 15 wherein the lower surface curvature
of the identified covering is flatter prior to placement than the
inner ablated portion of the eye by at least about 1D.
17. The apparatus of claim 15 wherein the inner portion of the
covering comprises a substantially uniform thickness and the
instructions are configured to identify a covering prior to
placement corresponding to hyperopia of the eye to improve vision
and inhibit an epithelial irregularity located on an inner portion
of the ablation and corresponding to nearsightedness of the
eye.
18. The apparatus of claim 17 wherein the instructions are
configured to identify the covering to inhibit formation of the
epithelial irregularity based on one or more of a modulus of the
inner portion of the covering, a thickness of the inner portion of
the covering, or an amount rigidity of the inner portion of the
covering.
19. The apparatus of claim 14 further comprising the plurality of
coverings.
20. The apparatus of claim 14 wherein the array of data comprises a
plurality of unique identifiers corresponding to the plurality of
coverings.
21. The apparatus of claim 20 wherein the plurality of unique
identifiers corresponds to a rigidity of an inner portion of each
of the plurality of coverings.
22. The apparatus of claim 20 wherein the covering comprises an
amount of rigidity of the inner portion within a range from about
1E-4 Pa*m 3 to about 5E-4 Pa*m 3.
23. The apparatus of claim 20 wherein the plurality of unique
identifiers comprises 10 or more unique identifiers corresponding
to an amount rigidity of the inner portion of at least about 3E-4
Pa*m 3.
24. The apparatus of claim 20 wherein the covering comprises an
amount of rigidity of the inner portion within a range from about
1E-4 Pa*m 3 to about 5E-4 Pa*m 3.
25. The apparatus of claim 20 wherein the array of data comprises a
first dimension corresponding to the inner ablated portion and a
second dimension corresponding to the outer portion away from the
ablated portion.
26. The apparatus of claim 25 wherein the array comprises a table,
the first dimension corresponding to rows of the table, the second
dimension corresponding to columns of the table and wherein the
plurality of unique identifiers is stored in the rows and the
columns of the table.
27. The apparatus of claim 25 wherein the display is visible to the
user and the instructions are configured to show the unique
identifier on the display.
28. The apparatus of claim 20, wherein the instructions are
configured to receive a conjunctiva sag height, the conjunctiva sag
height corresponding to a portion of a conjunctiva of the eye at a
radial location away from a reference axis of the eye and wherein
the instructions are configured such that the identified covering
comprises a covering sag height at a covering location
corresponding to the radial location of the portion of conjunctiva
and wherein the instructions are configured such that the covering
sag height is greater than the conjunctiva sag height.
29. The apparatus of claim 28 wherein the covering comprises an
inner portion having a hydrogel layer extending along a lower
surface to contact the ablated portion and the unablated portion of
the cornea and wherein the covering comprises an outer portion at
the covering location comprising a sticky tacky surface to contact
the conjunctiva and inhibit movement of the covering when the inner
portion contacts the cornea.
30. The apparatus of claim 29 wherein the inner portion of the
covering comprises a low water content water inhibiting layer
beneath the hydrogel layer and the outer portion of the covering at
the covering location to contact the conjunctiva comprises a soft
hydrophobic material.
31. The apparatus of claim 30 wherein the water inhibiting layer
comprises silicone elastomer and the hydrogel layer comprises
silicone hydrogel.
32. The apparatus of claim 28 wherein instructions are configured
such that the identified covering is deflected at the covering
location when the covering is placed on the eye.
33. The apparatus of claim 28 wherein the instructions are
configured to receive the conjunctiva sag height based on a
measurement of a sclera of the eye corresponding to the radial
location.
34. The apparatus of claim 14, wherein the instructions are
configured to receive a measurement the eye corresponding to a
limbus sag height, the limbus sag height corresponding to a portion
of a limbus of the eye at a radial location away from a reference
axis of the eye and wherein the instructions are configured such
that the covering comprises a covering sag height at a covering
location corresponding to the radial location of the portion of
limbus and wherein the instructions are configured such that the
covering sag height is no more than the limbus sag height.
35. The apparatus of claim 14, wherein instructions are configured
to identify the covering such that the identified covering is
deflected a first amount at a first covering location corresponding
to a portion of the conjunctiva when the covering is placed on the
eye and wherein the instructions are configured to identify the
covering such that the covering is deflected a second amount at a
second covering location corresponding to a portion of the limbus
when the covering is placed on the eye, the second amount less than
the first amount such that pressure from the covering over the
limbus is inhibited.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 13/885,135, which is the national of International Application
No. PCT/US2011/057755, filed on Oct. 25, 2011, which claims
priority under 35 U.S.C. 119(e) to U.S. Provisional Application No.
61/406,504 filed on Oct. 25, 2010, and U.S. Provisional Application
No. 61/480,231, filed on Apr. 28, 2011, each of which is
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention is generally directed to vision and
treatment of the eye to provide improved vision. Although specific
reference is made to coverings for vision correction such as the
correction of refractive error and also to treatment of eyes having
epithelial defects following photorefractive keratectomy,
embodiments of the present invention may comprise extended wear
contact lenses that can be used to correct vision in many ways such
as with one or more of aberration correction, multifocal
correction, presbyopia correction, and astigmatism correction.
[0003] The eye includes several tissues that allow patients to see.
The cornea of the eye is an anterior tissue of the eye that is
clear in healthy eyes and refracts light so as to form an image on
the retina. The retina is a posterior tissue of the eye that senses
light from the image formed thereon and transmits signals from the
image to the brain. The cornea includes an outer layer of tissue,
the epithelium, which protects the underlying tissues of the
cornea, such as Bowman's membrane, the stroma and nerve fibers that
extend into the stroma and Bowman's membrane. The healthy eye
includes a tear film disposed over the epithelium. The tear film
can smooth small irregularities of the epithelium so as to provide
an optically smooth surface. The tear film is shaped substantially
by the shape of the underlying epithelium, stroma, and Bowman's
membrane, if present. The tear film comprises a liquid that is
mostly water and does include additional components, such as
mucoids and lipids. The many nerve fibers of the cornea provide
sensation to promote blinking that can cover the cornea with the
tear film. The nerve fibers also sense pain so that one will
normally avoid trauma to the cornea and also avoid direct contact
of an object to the cornea so as to protect this important
tissue.
[0004] Work in relation to embodiments of the present invention
suggests that at least some of the prior contact lenses and
therapeutic coverings can be less than ideal in at least some
instances. Many contact lenses and therapeutic coverings can be
left in the eye for less than ideal amounts of time, as the patient
removing and replacing the contact lens or therapeutic covering can
be somewhat cumbersome and in at least some instances patients may
leave the contact lens or therapeutic covering in the eye for
amounts of time that can be longer than would be ideal. Although
extended wear lenses can be left in the eye for somewhat longer
amounts of time, the amount of time such lenses can be left in the
eye can be less than ideal. Work in relation to embodiments of the
present invention also suggests that tear flow of the prior contact
lenses can be less than ideal, and that less than ideal tear flow
may be related to the potential complications and can limit the
amount of time such lenses can be left in the eye.
[0005] In the healthy cornea, the proper amount of hydration of the
cornea, sometimes referred to as dehydration of the cornea, is
maintained such that the cornea remains clear. The cornea includes
a posterior endothelial layer that pumps water from the cornea into
the adjacent anterior chamber. The epithelium inhibits flow of
water from the tear liquid into the cornea, such that the corneal
stroma can be maintained with the proper amount of hydration with
endothelial pumping. The endothelial pumping of water from the
cornea to maintain the proper hydration and thickness of the eye is
often referred to as deturgescence. When the corneal epithelium
heals, the layer of cells forming over the defect can be at least
somewhat irregular in at least some instances, such that the vision
of the patient can be less than ideal.
[0006] As the post-ablation cornea may have a complex shape, many
of the prior commercially available lenses may not fit the ablated
cornea as well as would be ideal, and in at least some instances
fitting of lenses can be time consuming and awkward. Rigid gas
permeable (hereinafter "RGP") lenses can be uncomfortable for the
patient and difficult to fit. Commercially available contact lenses
having a rigid central portion and a soft peripheral skirt can be
difficult and/or time consuming to fit to the ablated cornea and
may not fit very well in at least some instances. The ablated
cornea may comprise an abrupt change in curvature near the edge of
the ablation, and in at least some instances it can be difficult to
fit such lenses near the edge of the ablation. Also, at least some
of the commercially available contact lenses may not be suitable
for extended wear and may be removed each day, which can be
somewhat awkward for a patient and can result in lack of compliance
and lenses remaining in the eye longer than would be ideal in at
least some instances.
[0007] In light of the above, it would be desirable to provide
improved contact lenses for vision correction and coverings for
treatments related to epithelial defects of the cornea, such as
epithelial defects following photorefractive keratectomy
(hereinafter "PRK"). Ideally, these contact lenses and coverings
would provide treatments that improve tear flow and avoid at least
some of the deficiencies of known techniques while providing
improved patient comfort and/or vision.
BRIEF SUMMARY OF THE INVENTION
[0008] Embodiments of the present invention provide improved
methods and apparatus to fit and identify coverings to treat eyes.
The treated eye may comprise a natural eye, or an eye having an
epithelial defect of the eye, such as an eye ablated with PRK
refractive surgery. In many embodiments, the covering can be
identified and fit to the eye so as to provide one or more of
improved hydration or flow of tear liquid under the covering. The
covering can be fit and identified based on an inner corneal
curvature and an outer corneal curvature and one or more of a
limbus sag height or a conjunctival sag height.
[0009] The covering to fit the eye may comprise a contact lens and
can provide improved hydration and tear flow such that the covering
can be left on the eye to correct vision for extended amounts of
time. The covering may comprise one or more structures to provide
hydration under the covering such that the covering can remain in
the eye and correct vision for an extended amount of time. In many
embodiments, the covering comprises a layer of hydrogel extending
along a lower surface of the covering to provide hydration to a
surface of the eye. Alternatively or in combination, the covering
may comprise a material having fenestrations and an outer portion
shaped to contact the conjunctiva to pump tear liquid when the eye
blinks. The covering may comprise a deflectable outer portion
having a resistance to deflection such that a chamber is formed
when the covering is placed on the eye and the eye is open with the
eyelids separated. The resistance to deflection of the deflectable
outer portion is configured such that the outer portion deflects
inward toward the cornea when the eyelid closes to pump tear
liquid. The fenestrations can draw tear liquid into the chamber
located under the covering when the eye opens and the chamber can
expand. The outer portion of the covering comprises a sclera
coupling portion shaped to contact the conjunctiva to define the
chamber when the covering is placed on the eye. The fenestrations
and sclera coupling portion of the covering can pass tear liquid
away from the chamber when the eye closes and pressure of one or
more eyelids urges the covering toward the cornea such that the
chamber volume decreases. In many embodiments, opening of the eye
so as to separate the eyelids reduces pressure on the outer portion
of the covering such that the outer portion of the covering over an
outer portion of the cornea can separate from the outer portion of
the cornea so as to draw liquid through the fenestrations and into
the chamber located under the covering. The sclera coupling portion
of covering may contact the conjunctiva to inhibit the flow of tear
liquid under the sclera coupling portion when the eye opens and
tear liquid is drawn through the fenestrations, for example with
formation of a seal where the covering contacts the conjunctiva.
When the eye blinks subsequently, the pressure of the one or more
eyelids can urge the covering toward the cornea such that tear
liquid can pass through the fenestrations, and the sclera coupling
portion may separate slightly from the conjunctiva to pass tear
liquid under the sclera coupling portion, so as to rinse the
cornea, the limbus, the conjunctiva and the underside of the
covering with the pumped tear liquid. The covering may comprise a
material having high oxygen permeability such as silicone such that
the covering may provide improved tear flow and high oxygen
permeability. This improved flow of tear liquid can allow the
covering such as a contact lens to be worn for extended amounts of
time of at least about one week, for example thirty days or sixty
days or more. The improved tear flow can improve healing and vision
of eyes with epithelial defects, for example epithelial defects
following PRK.
[0010] In many embodiments, the identified covering comprises an
inner optical component for vision, such as a lens, and an outer
coupling component to hold the inner component in relation to the
pupil to improve vision. The coupling component may comprise a
deflectable material that inhibits passage of the tear liquid
through the material such that the tear liquid passes through the
fenestrations when the eye blinks and an eyelid exerts pressure on
the optical component. The outer coupling component may comprise
the fenestrations to pass the tear liquid and the outer sclera
coupling portion to contact the conjunctiva. The optical component
may comprise a first material and first thickness corresponding to
a first rigidity. The coupling component may comprise a second
material and a second thickness corresponding to a second rigidity.
The second material can be softer than the first material and the
second thickness can be less than the first thickness such that the
coupling component can be deflected with the eyelid, and such that
the coupling component can be deflected by an amount greater than
the optical component when the eyelids close to cover the first
component and the second component. The optical component can be
more rigid than the coupling component, such that the optical
component can provide vision when the outer portion is deflected
with one or more eyelids.
[0011] The covering can be identified such that the alignment of
the optical component to the pupil provided with the coupling to
the conjunctiva and underlying sclera can be beneficial for vision.
The optical component can be held at a substantially fixed location
in relation to the pupil so as to provide improved vision such as
presbyopia correction and vision correction of aberrations that may
depend on location of the pupil such as measured wavefront
aberrations, spherical aberration, coma and trefoil.
[0012] The covering can be identified such that the optical
component and coupling component can be helpful to improve vision
and regeneration of the epithelium in eyes with epithelial defects.
The optical component can smooth the cornea and may smooth
irregularities of the epithelium and ablated stroma. The coupling
component can support the optical component so as to resist sliding
movement of the optical component and provide an environment to
promote regeneration of the epithelium. The pumping of the tear
liquid may improve tear flow to the regenerating epithelium near
the epithelial defect so as to promote regeneration of the
epithelium over the defect. The pumping of the tear liquid can also
promote delivery of a medicament, for example a steroid, to the
ablated region so as to inhibit corneal infiltrates and haze.
[0013] In many embodiments, the covering can be identified based on
one or more of pre-operative eye data used to determine the
ablation, ablation data of the laser such as the amount of ablative
correction, and dimensions across the ablated region of the eye.
The covering may comprise an inner portion having a lower surface
comprising a curvature, and the curvature can be less than a
curvature of the ablated profile to improve vision and inhibit
formation of one or more irregularities of the epithelium. The one
or more irregularities may be located on an inner portion of the
ablation comprising a center of the ablation, and the covering may
comprise a resistance to deflection to inhibit formation of the one
or more irregularities near the center of the ablation. The
irregularity may comprise an elevated profile of the epithelium
located on the inner portion comprising the center of the ablation,
and the inner portion of the covering may comprise resistance to
deflection and provide pressure in response to deflection of the
inner portion so as to inhibit formation of the one or more
irregularities of the epithelium. As the covering can resist
deflection, the covering can be identified based on eye measurement
data and ablation data so as to provide comfort and improved vision
to the patient when the covering is placed on the eye and improves
vision. A plurality of coverings having portions sized to fit the
patient can be provided. A covering to treat the patient can be
identified among the plurality of coverings based on data
corresponding to an untreated portion of the eye, data
corresponding to a treated portion of the eye, and an array of data
corresponding to rigidity of the plurality of coverings. The array
of data may comprise the unique identifiers arranged such that the
unique identifier can be determined from the array based on the
data corresponding to an untreated portion of the eye and the data
corresponding to a treated portion of the eye. The identified
covering can be placed on the eye and promote regeneration of the
epithelium with improved vision and comfort.
[0014] In a first aspect, embodiments provide a method of treating
an eye of a patient, in which the eye has a cornea. The eye is
measured to determine data of the eye corresponding to an inner
ablated portion of the cornea and an outer unablated portion of the
cornea away from the ablated portion. A covering of a plurality of
coverings is identified to treat the eye based on the data of the
eye and an array of data corresponding to the plurality of
therapeutic coverings.
[0015] In many embodiments, the covering is placed on the eye.
[0016] In many embodiments, the covering comprises an inner
covering portion and an outer covering portion, the inner covering
portion contacting the inner ablated portion of the cornea and an
outer covering portion contacting an unablated portion when placed
on the cornea and wherein the inner covering portion prior to
placement on the eye has a covering curvature no more than a
curvature of the ablated portion of the cornea and wherein the
outer covering portion comprises a curvature prior to placement on
the eye no more than the outer unablated portion of the cornea and
wherein the covering resists movement of the inner portion when
placed on the eye.
[0017] In many embodiments, the outer portion of the covering
extends to a conjunctiva of the eye and couples to the sclera of
the eye to resist movement of the inner portion.
[0018] In many embodiments, the inner portion of the covering prior
to placement comprises a substantially uniform thickness and an
amount of curvature corresponding to less optical power than the
optical power of the ablated portion of the cornea, the amount of
curvature of the inner portion prior to placement within a range
from about -1D to about -3D relative to the ablated portion of the
cornea.
[0019] In many embodiments, the inner portion of the covering
deflects at least about 1D so as to conform at least partially to
the ablation and promote smooth epithelial regeneration and
vision.
[0020] In many embodiments, the inner portion of the covering
comprises an amount of rigidity within a range from about 1E-4 to
about 5E-4 (Pa*m 3) and the outer portion of the covering comprises
an outer amount of rigidity less than the amount of rigidity of the
inner portion.
[0021] In many embodiments, measuring the eye comprises determining
a conjunctiva sag height, in which the conjunctiva sag height
corresponds to a portion of a conjunctiva of the eye at a radial
location away from a reference axis of the eye. The covering
comprises a covering sag height at a covering location
corresponding to the radial location of the portion of conjunctiva,
and the covering is identified such that the covering sag height is
greater than the conjunctiva sag height.
[0022] In many embodiments, the covering is deflected at the
covering location when the covering is placed on the eye.
[0023] In many embodiments, the conjunctiva sag height is
determined based on a measurement of a sclera of the eye
corresponding to the radial location.
[0024] In many embodiments, measuring the eye comprises determining
a limbus sag height, the limbus sag height corresponding to a
portion of a limbus of the eye at a radial location away from a
reference axis of the eye and wherein the covering comprises a
covering sag height at a covering location corresponding to the
radial location of the portion of the limbus and wherein the
covering is identified such that the covering sag height is no more
than the limbus sag height.
[0025] In many embodiments, the covering is deflected a first
amount at a first covering location corresponding to a portion of
the conjunctiva when the covering is placed on the eye and wherein
the covering is deflected a second amount at a second covering
location corresponding to a portion of the limbus when the covering
is placed on the eye, the second amount less than the first amount
such that pressure from the covering to the limbus is
inhibited.
[0026] In many embodiments, the covering comprises an inner portion
having a hydrogel layer extending along a lower surface to contact
the ablated portion and the unablated portion of the cornea and
wherein the covering comprises an outer portion comprising a
sticky, tacky surface to contact the conjunctiva and inhibit
movement of the covering when the inner portion contacts the
cornea
[0027] In another aspect, embodiments provide an apparatus to treat
an eye. The apparatus comprises an input to receive data of the
eye. The data of the eye corresponds to an inner ablated portion of
the cornea and an outer portion of the cornea away from the inner
ablated portion. The apparatus comprises an output. At least one
processor is coupled to the input and the output. The at least one
processor comprises at least one computer readable memory. The at
least one computer readable memory has instructions to store an
array of data corresponding to a plurality of therapeutic coverings
and instructions to identify a covering of the plurality based on
the array and the data of the eye corresponding to the inner
ablated portion and the outer portion.
[0028] In many embodiments, the apparatus comprises the plurality
of coverings.
[0029] In many embodiments, the instructions are configured to
identify a covering having an inner portion comprising a lower
surface curvature flatter than the inner ablated portion of the eye
to inhibit one or more irregularities of the epithelium.
[0030] In many embodiments, the lower surface curvature of the
identified covering is flatter prior to placement than the inner
ablated portion of the eye by at least about 1D.
[0031] In many embodiments, the inner portion of the covering
comprises a substantially uniform thickness and the instructions
are configured to identify a covering prior to placement
corresponding to hyperopia of the eye to improve vision and inhibit
an epithelial irregularity located on an inner portion of the
ablation and corresponding to nearsightedness of the eye.
[0032] In many embodiments, the instructions are configured to
identify the covering to inhibit formation of the epithelial
irregularity based on one or more of a modulus of the inner portion
of the covering, a thickness of the inner portion of the covering,
or an amount of rigidity of the inner portion of the covering.
[0033] In many embodiments, the array of data comprises a plurality
of unique identifiers corresponding to the plurality of
coverings.
[0034] In many embodiments, the plurality of unique identifiers
corresponds to a rigidity of an inner portion of each of the
plurality of coverings.
[0035] In many embodiments, the covering comprises an amount of
rigidity of the inner portion within a range from about 1E-4 Pa*m 3
to about 5E-4 Pa*m 3.
[0036] In many embodiments, the plurality of unique identifiers
comprises 10 or more unique identifiers corresponding to an amount
of rigidity of the inner portion of at least about 3E-4 Pa*m 3.
[0037] In many embodiments, the covering comprises an amount of
rigidity of the inner portion within a range from about 1E-4 Pa*m 3
to about 5E-4 Pa*m 3.
[0038] In many embodiments, the array of data comprises a first
dimension corresponding to the inner ablated portion and a second
dimension corresponding to the outer portion away from the ablated
portion.
[0039] In many embodiments, the array comprises a table, the first
dimension corresponding to rows of the table, the second dimension
corresponding to columns of the table and wherein the plurality of
unique identifiers is stored in the rows and the columns of the
table.
[0040] In many embodiments, the display is visible to the user and
the instructions are configured to show the unique identifier on
the display.
[0041] In many embodiments, the instructions are configured to
receive a conjunctiva sag height, the conjunctiva sag height
corresponding to a portion of a conjunctiva of the eye at a radial
location away from a reference axis of the eye. The instructions
are configured such that the identified covering comprises a
covering sag height at a covering location corresponding to the
radial location of the portion of conjunctiva and wherein the
instructions are configured such that the covering sag height is
greater than the conjunctiva sag height.
[0042] In many embodiments, the covering comprises an inner portion
having a hydrogel layer extending along a lower surface to contact
the ablated portion and the unablated portion of the cornea, and
the covering comprises an outer portion at the covering location
comprising a sticky tacky surface to contact the conjunctiva and
inhibit movement of the covering when the inner portion contacts
the cornea.
[0043] In many embodiments, the inner portion of the covering
comprises a low water content water inhibiting layer beneath the
hydrogel layer, and the outer portion of the covering at the
covering location to contact the conjunctiva comprises a soft
hydrophobic material.
[0044] In many embodiments, the water inhibiting layer comprises
silicone elastomer and the hydrogel layer comprises silicone
hydrogel.
[0045] In many embodiments, instructions are configured such that
the identified covering is deflected at the covering location when
the covering is placed on the eye.
[0046] In many embodiments, the instructions are configured to
receive the conjunctiva sag height based on a measurement of a
sclera of the eye corresponding to the radial location.
[0047] In many embodiments, the instructions are configured to
receive a measurement the eye corresponding to a limbus sag height,
in which the limbus sag height corresponds to a portion of a limbus
of the eye at a radial location away from a reference axis of the
eye. The instructions are configured such that the covering
comprises a covering sag height at a covering location
corresponding to the radial location of the portion of limbus, and
the instructions are configured such that the covering sag height
is no more than the limbus sag height.
[0048] In many embodiments, the instructions are configured to
identify the covering such that the identified covering is
deflected a first amount at a first covering location corresponding
to a portion of the conjunctiva when the covering is placed on the
eye, and the instructions are configured to identify the
coveringsuch that the covering is deflected a second amount at a
second covering location corresponding to a portion of the limbus
when the covering is placed on the eye, the second amount less than
the first amount such that pressure from the covering over the
limbus is inhibited.
[0049] In another aspect embodiments provide an apparatus to treat
an eye. The apparatus comprises an input, an output and at least
one processor. The input is configured to receive data of the eye,
and the data of the eye correspond to an inner portion of the
cornea and one or more of a limbus or a conjunctiva of the eye. The
at least one processor is coupled to the input and the output. The
at least one processor comprises at least one computer readable
memory. The at least one computer readable memory has instructions
to store an array of data corresponding to a plurality of coverings
and instructions to identify a covering of the plurality based on
the data of the eye and the array of data corresponding to the
plurality of coverings, such tear liquid is pumped under the
covering when the eye blinks.
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] FIG. 1 shows an eye suitable for incorporation of the
covering as described herein, in accordance with embodiments of the
present invention;
[0051] FIG. 1-1A shows an ablated eye immediately following
refractive surgery resulting in an epithelial defect, suitable for
incorporation in accordance with embodiments of the present
invention;
[0052] FIG. 1-1B shows an ablated eye about 1 day following
refractive surgery resulting in an epithelial defect, suitable for
incorporation, in accordance with embodiments of the present
invention;
[0053] FIG. 1-1C shows an ablated eye when the epithelium has
regenerated following refractive surgery resulting in an increased
epithelial thickness centrally at about 3 days, suitable for
incorporation, in accordance with embodiments of the present
invention;
[0054] FIG. 1-2A shows a covering positioned on an eye having an
epithelial defect, in which the covering abuts the cornea to seal
the cornea, in accordance with embodiments of the present
invention;
[0055] FIG. 1-2B shows a smooth layer of regenerated epithelium
substantially cover an ablated profile, in accordance with
embodiments of the present invention;
[0056] FIG. 1A shows a covering positioned on an eye having an
epithelial defect, in which an outer portion of the covering abuts
and conforms at least partially to the cornea to seal the cornea,
in accordance with embodiments of the present invention;
[0057] FIG. 1A1 shows a covering positioned on an eye and blinking
of the eye, in accordance with embodiments of the present
invention;
[0058] FIG. 1B1 shows a covering sized to seal a cornea, in
accordance with embodiments of the present invention;
[0059] FIG. 1B2 shows the covering conforming to ablated stromal
tissue and guiding regeneration of the epithelium over the ablated
stroma, so as to promote vision, in accordance with embodiments of
the present invention;
[0060] FIG. 1B2A shows a covering forming an indentation in the
epithelium such that the epithelium extends over at least a portion
of the perimeter of the covering, in accordance with embodiments of
the present invention;
[0061] FIG. 1B2B shows a covering forming an indentation in the
epithelium, in accordance with embodiments of the present
invention;
[0062] FIG. 1B2C shows a covering abutting the cornea to seal the
cornea without forming a substantial indentation in the epithelium,
in accordance with embodiments of the present invention;
[0063] FIG. 1C shows a covering comprising a single piece of
material having an inner thickness greater than an outer thickness,
in accordance with embodiments of the present invention;
[0064] FIG. 1C1 shows a covering as in FIGS. 1-2A to 1B2 having an
inner portion comprising an inner thickness and an inner material
and an outer portion comprising an outer thickness and an outer
material, in which the inner thickness is greater than the outer
thickness, in accordance with embodiments of the present
invention;
[0065] FIG. 1C1A shows a covering as in FIG. 1C1 adhered to the
cornea with a smooth upper surface and a lower surface conforming
to irregularity of the cornea comprising a central island of the
stroma, in accordance with embodiments of the present
invention;
[0066] FIG. 1C2 shows a covering as in FIGS. 1-2A to 1B2 having an
inner portion comprising an inner thickness and an inner material
and an outer portion comprising an outer thickness and an outer
material, in which the inner thickness is greater than the outer
thickness and the outer material extends around the inner material,
in accordance with embodiments of the present invention;
[0067] FIG. 1C2A shows a covering as in FIG. 1C1 adhered to the
cornea with a smooth upper surface and a lower surface conforming
to irregularity of the cornea near the edge of the ablation, in
accordance with embodiments of the present invention;
[0068] FIG. 1C2A1 shows a covering having a layer of hydrogel
material on a posterior surface of the covering, in accordance with
embodiments of the present invention;
[0069] FIG. 1C2B shows a covering having a layer of hydrogel
material on a posterior surface of the covering extending less than
a maximum distance across the covering such that end portions of
the covering are configured to engage the epithelium of the eye
away from the hydrogel layer and inhibit movement of the covering
when placed on the eye, in accordance with embodiments of the
present invention;
[0070] FIG. 1C2C shows a covering having an annular layer of
hydrogel material on a posterior surface of the covering such that
an inner portion of the covering contacts the cornea away from the
hydrogel layer and an outer portion of the covering contacts the
cornea away from the covering when placed on the eye, in accordance
with embodiments of the present invention;
[0071] FIG. 1C3 shows a covering having a tricurve profile to fit
sclera with slopes of the curved profiles aligned so as to inhibit
ridges at the boundaries of the curved portions as in FIG. 1B2 and
having a layer of hydrogel material on a lower surface, in
accordance with embodiments of the present invention;
[0072] FIG. 1C4 shows a side cross-sectional view covering having a
tricurve profile to fit the cornea, limbus and sclera with slopes
of the curved profiles aligned so as to inhibit ridges at the
boundaries of the curved portions and having a hydrogel material on
a lower surface extending less than a maximum distance across the
covering to engage the conjunctiva with the covering away from the
hydrogel material, in accordance with embodiments of the present
invention;
[0073] FIG. 1C5 shows a fenestration having a posterior end covered
with a layer of hydrogel extending along the posterior surface of
the covering, in accordance with embodiments of the present
invention;
[0074] FIG. 1C6 shows a fenestration extending through a layer of
hydrogel extending along the posterior surface of the covering, in
accordance with embodiments of the present invention;
[0075] FIG. 1D shows a covering as in FIGS. 1-2A to 1B2 having an
inner portion comprising an inner thickness and an inner material
and an outer portion comprising an outer thickness and an outer
material, in which the inner thickness is substantially similar to
the outer thickness, in accordance with embodiments of the present
invention;
[0076] FIGS. 1E and 1F show top and side views, respectively, of a
covering comprising an inner portion and an outer portion, as in
FIGS. 1A to 1B2 and a peripheral rim portion disposed around the
outer portion, in accordance with embodiments of the present
invention;
[0077] FIG. 1G shows a covering comprising an inner portion and an
outer portion comprising a taper, in accordance with embodiments of
the present invention;
[0078] FIG. 1G1 shows a covering comprising an inner portion and an
outer portion comprising a taper and an outer rim of substantially
uniform thickness peripheral to the taper, in accordance with
embodiments of the present invention;
[0079] FIGS. 1G1A to 1G1G show a covering as in FIG. 1G1 and
dimensions suitable for use with experiments, clinical studies, and
patient treatment, in accordance with embodiments of the present
invention;
[0080] FIG. 1H1 shows spatial frequency and elevation smoothing of
an epithelial irregularity transferred to a front surface of a
covering as in FIG. 1-2A, in accordance with embodiments of the
present invention;
[0081] FIG. 1H2 shows spatial frequency and elevation smoothing of
the epithelial irregularity with a plot of height relative to a
reference sphere for the upper surface of the covering and the
upper surface of the irregularity, in accordance with embodiments
of the present invention;
[0082] FIG. 1I1 shows inhibition of transfer of an epithelial
irregularity to a front surface of a covering, in accordance with
embodiments of the present invention;
[0083] FIG. 1I2 shows elevation smoothing of the epithelial
irregularity with a plot of height relative to a reference sphere
for the upper surface of the covering and the upper surface of the
irregularity, in accordance with embodiments of the present
invention;
[0084] FIG. 1I3 shows a thickness profile of the covering as in
FIG. 112 so as to smooth the front surface of the covering, in
accordance with embodiments of the present invention;
[0085] FIG. 1J1 shows a covering having a bicurve profile to fit an
ablated cornea, in accordance with embodiments of the present
invention;
[0086] FIG. 1J2 shows a covering having an oblate profile to fit an
ablated cornea, in accordance with embodiments of the present
invention;
[0087] FIG. 1J3 shows a covering having a tricurve profile to fit
sclera and an ablated cornea, in accordance with embodiments of the
present invention;
[0088] FIG. 1J4 shows a covering having a curved profile to fit
sclera and an oblate profile to fit ablated cornea, in accordance
with embodiments of the present invention;
[0089] FIG. 1J5 shows a covering having a tricurve profile to fit
sclera and an ablated cornea similar to FIG. 1J3, in accordance
with embodiments of the present invention;
[0090] FIG. 1J6 shows a tapered edge of the covering having a
tricurve profile to fit sclera and an ablated cornea as in FIG.
1J5, in accordance with embodiments of the present invention;
[0091] FIG. 1K shows a covering having fenestrations on an outer
portion to pass a medicament when the cornea is sealed, in
accordance with embodiments of the present invention;
[0092] FIG. 1L shows fitting of a covering to a cornea, in
accordance with embodiments of the present invention;
[0093] FIG. 1M shows deflection of a portion of a covering in
response to an epithelial irregularity so as to smooth the
irregularity, in accordance with embodiments as described
herein;
[0094] FIG. 1N shows a test apparatus to measure deflection of a
portion of a lens in response to a load, in accordance with
embodiments as described herein;
[0095] FIG. 2A1 shows a covering positioned on an eye and blinking
of the eye, in accordance with embodiments of the present
invention;
[0096] FIG. 2A2 shows the covering of FIG. 2A1 that is capable of
pumping tear liquid under the covering, in accordance with
embodiments of the present invention;
[0097] FIG. 2A3 shows a schematic illustration of the covering of
FIGS. 2A1 and 2A2 pumping tear liquid when the eye closes, in
accordance with embodiments of the present invention;
[0098] FIG. 2A4 shows a schematic illustration of the covering of
FIGS. 2A1 and 2A2 pumping tear liquid when the eye opens, in
accordance with embodiments of the present invention;
[0099] FIG. 2B1 shows a covering having a tricurve profile to fit
sclera, which covering may be used to fit an ablated cornea, in
accordance with embodiments of the present invention;
[0100] FIG. 2B2 shows a covering having a tricurve profile to fit
sclera with slopes of the curved profiles aligned so as to inhibit
ridges at the boundaries of the curved portions, in accordance with
embodiments of the present invention;
[0101] FIG. 2B2-1 shows alignment of the slope of the lower surface
of the corneal contacting portion with the slope of the lower
surface of the sclera coupling portion, such that pressure to the
limbus is decreased substantially, in accordance with embodiments
of the present invention;
[0102] FIG. 2B3 shows a tapered edge of the covering of FIG. 2B1,
in accordance with embodiments of the present invention;
[0103] FIG. 2B4 shows a plan view of the covering having a tricurve
profile to fit the cornea, limbus, and sclera with slopes of the
curved profiles aligned so as to inhibit ridges at the boundaries
of the curved portions, in accordance with embodiments of the
present invention;
[0104] FIG. 2B5 shows a side sectional view of the covering of FIG.
2B4 and corresponding curved portions to couple to the cornea,
limbus and, sclera, in accordance with embodiments of the present
invention;
[0105] FIG. 2B6 shows a side sectional view of the covering of FIG.
2B4 and corresponding curved portions of the upper surface, in
accordance with embodiments of the present invention;
[0106] FIG. 2B7 shows a tapered edge of the covering of FIG. 2B4,
in accordance with embodiments of the present invention;
[0107] FIG. 3A shows a covering comprising a contact lens placed on
the eye with the eyelids separated, in accordance with embodiments
of the present invention;
[0108] FIG. 3B shows a side sectional view of the covering of FIG.
3A with the eyelids closing, in accordance with embodiments of the
present invention;
[0109] FIG. 3C shows a front view the covering of FIG. 3A with the
eyelids closing, in accordance with embodiments;
[0110] FIG. 3D shows side profile the covering of FIG. 3A with the
eyelids opening, in accordance with embodiments of the present
invention;
[0111] FIG. 3E shows a covering comprising a contact lens placed on
the eye such that the covering is supported with an inner portion
of the cornea and the conjunctiva with the covering separated from
an outer portion of the cornea so as to define a chamber when the
eyelids are separated, in accordance with embodiments of the
present invention;
[0112] FIG. 3F shows a side sectional view of the covering of FIG.
3E with the eyelids closing, in accordance with embodiments of the
present invention;
[0113] FIG. 3F1 shows a side sectional view of the covering of FIG.
3F with rotation of the eye when the lids close such that sliding
of the covering along the epithelium is inhibited when tear liquid
is pumped, in accordance with embodiments of the present
invention;
[0114] FIG. 3G shows a side sectional view of the covering of FIG.
3E with the eyelids opening, in accordance with embodiments of the
present invention;
[0115] FIG. 3H shows a side sectional view of the covering of FIG.
3E with the eyelids located at an intermediate location such that
the chamber comprises an intermediate volume, in accordance with
embodiments of the present invention;
[0116] FIG. 3I shows a side sectional view of the covering of FIG.
1C4 placed on the eye with hydrogel contacting the eye, in
accordance with embodiments of the present invention;
[0117] FIG. 4 shows apparatus and coverings to treat an eye, in
accordance with embodiments of the present invention;
[0118] FIG. 4A shows data structures and a method of identifying a
covering, in accordance with embodiments of the present invention;
and
[0119] FIG. 4B shows data structures and the method of identifying
the covering as FIG. 4A, in which the fit parameters comprise a two
fit parameters and the data array comprises a two dimensional look
up table, in accordance with embodiments of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0120] Embodiments of the present invention as described herein can
be combined with the therapeutic covering device for pain
management and vision as described in U.S. patent application Ser.
No. 12/384,659, filed Apr. 6, 2009, entitled "Therapeutic Device
for Pain Management and Vision", the full disclosure of which is
incorporated herein by reference and suitable for combination in
accordance with some embodiments of the present invention as
described herein.
[0121] The embodiments described herein can be used to treat eyes
in many ways with a covering. Although specific reference is made
to treating epithelial defects of the eye, the covering described
herein can be used for long term vision correction with extended
wear contact lenses that inhibit swelling of the cornea when the
covering is positioned on the eye for an extended period.
[0122] The coverings as described herein can seal the cornea, so as
to restore deturgescence of the cornea to decrease pain and improve
vision. The covering can be configured in many ways to seal the
cornea, and the covering comprises a substantially oxygen
permeability to promote growth of the epithelium and to guide the
growth of the epithelium such that the epithelium regenerates
smoothly for patient vision. The restoration of deturgescence of
the cornea can decrease irregularities of the cornea such as
ablated stromal irregularities, for example central islands. The
sealing of the cornea with the environment to promote epithelial
regeneration can result in improved epithelial smoothness and an
improved profile of the ablated stromal surface under the
regenerating epithelium.
[0123] In many embodiments, the covering comprises an at least
partially conformable portion, such that the at least partially
conformable portion can one or more of match or grossly approximate
the corrected corneal curvature so as to provide vision of at least
about 20/30, and such that the at least partially conformable
portion substantially does not conform to the corneal
irregularities caused by epithelial healing and edema, such as
irregularities of the epithelium and central islands that may
appear post-ablation in ablated eye.
[0124] In many embodiments, the at least partially conformable
portion of the covering can be configured so as to conform at least
partially to the epithelium when the covering is positioned on the
epithelium so as to deflect the epithelium.
[0125] The epithelium can conform to the covering so as to seal the
covering, for example with deformation of the epithelium such as
with one or more of indentation or overgrowth of the epithelium
around a perimeter of the covering.
[0126] In many embodiments, the curvature of the covering can match
substantially the profile of the ablated region, so as to provide
visions of at least about 20/30 when positioned on the cornea.
[0127] As used herein, mathematical equations and scientific
notation can be used to values in many ways understood by a person
of ordinary skill in the art, for example so as to express data in
accordance with notations used in many commercially available
spreadsheets such as Excel.TM. commercially available from
Microsoft. As used herein the symbol "E" can be used to express an
exponent in base 10, such that 1E1 equals about 10, 2E1 equals
about 20, and 4E2 equals about 400. As used herein the symbol " "
can be used to express an exponent, such that A B equals A.sup.B.
Units can be expressed in many ways and as would be understood by a
person of ordinary skill in the art, for example "m" as meters,
"Pa" as the Pascal unit for pressure, and "MPa" as Mega Pascal.
[0128] FIG. 1 shows an eye 2 suitable for incorporation of the
covering 100 as described herein. The eye has a cornea 10 and a
lens 4 configured to form an image on the retina 5, and the image
can form on a fovea 5F corresponding to high visual acuity. The
cornea can extend to a limbus 6 of the eye, and the limbus can
connect to a sclera 7 of the eye. The eye 2 has a pars plana PP
located near limbus 6. A conjunctiva 7C of the eye can be disposed
over the sclera 7. The lens can accommodate to focus on an object
seen by the patient. The eye has an iris 8 that defines a pupil 9
that may expand and contract in response to light. The eye also
comprises a choroid CH disposed between the sclera 7 and the retina
5. The eye has a vitreous humor VH extending between the lens and
the retina. The retina 5 senses light of the image and converts the
light image to neural pulses that are processed and transmitted
along an optic nerve ON to the brain of the patient.
[0129] FIG. 1-1A shows an ablated eye immediately following
refractive surgery, for example PRK surgery resulting in an
epithelial defect. The eye 2 comprises an iris 8 that defines a
pupil 9, through which light passes such that the patient can see.
Cornea 10 includes an epithelium 12 disposed over a stroma 16. The
epithelium 12 comprises an unablated outerperipheral portion having
12P having a thickness 12T that can be about 50 um. A tear
liquidcovers the anterior surface of epithelium 12. In at least
humans, primates and some birds, a Bowman's membrane 14 is disposed
between epithelium 12 and stroma 16. Bowman's membrane 14 comprises
an acellular substantially collagenous tissue with a thickness of
about 5 to 10 microns. Stroma 16 comprises a substantially
collagenous tissue with keratocytes disposed therein. In some
animals, Bowman's membrane may be absent and the epithelium may be
disposed adjacent to the stromal layer. An endothelium 18 is
disposed under stroma 16. Endothelium 18 comprises a layer of cells
that pump water from cornea 10 toward iris 8. Tear liquid also
covers surfaces of the cornea that are exposed by the epithelial
defect, such as an exposed surface of Bowman's membrane and an
exposed stromal surface.
[0130] In a normal healthy eye, epithelium 12 is disposed across
cornea 10 and is a protective layer. Epithelium 12 covers nerves of
the cornea and minimizes the flow of water from the tear film of
the eye to into the stroma. Epithelium 12 in most human patients
can be about 40 to 60 microns thick, for example about 50 microns.
When epithelium 12 is intact, endothelium 18 can pump water from
stroma 16 and maintain hydration in the cornea at a proper level.
The mechanism by which the stroma of the cornea remains properly
hydrated can be referred to as deturgescence. Deturgescence of the
cornea can be important because excess hydration of the cornea can
result in swelling of the cornea and light scattering, or haze,
that can degrade vision. The total thickness of normal cornea 10
from endothelium 18 to tear liquid in most human patients can be
from about 400 to 600 microns. A healthy cornea with normal
hydration comprises about 80 to 85% water. Edema of the cornea due
to swelling of the cornea, for example with additional water, can
increase the thickness of the cornea.
[0131] With refractive surgery, for example PRK, the epithelium can
be removed to ablate a refractive correction into Bowman's membrane
14 and/or stroma 16. An initial profile of the anterior surface of
stroma and/or Bowman's membrane is ablated to an ablated profile 20
to correct the patient's vision. The profile of tissue removed to
correct vision is described in U.S. Pat. No. 5,163,934, entitled
"Photorefractive Keratectomy", the disclosure of which may be
suitable for combination in accordance with some embodiments of the
present invention described herein. Ablated profile 20 generally
comprises an optical zone that extends across the cornea to correct
refractive error of the eye and may correct aberrations of the eye,
for example wavefront aberrations. Ablated profile 20 is bounded by
boundary 20B that may circumscribe the ablated profile. The
ablation profile 20 comprises a maximum dimension across, for
example a diameter 20D.
[0132] The epithelium may comprise an inner boundary that moves
centripetally inward as indicated by arrows 30
[0133] FIG. 1-1B shows an ablated eye about 1 to 2 days following
refractive surgery resulting in an epithelial defect. The
epithelium has at least partially covered the ablation. The
epithelium may comprise irregularities and an inner boundary that
moves centripetally inward as indicated by arrows 30. The thickness
profile 12RP of the regenerating epithelium 12R can be irregular
and degrade vision. The inner portion of the epithelium near the
boundary may comprise a height greater than an outer portion of the
epithelium away from the boundary of the epithelium. The portion of
the ablation not covered with the epithelium and the inner portion
of the epithelium near the boundary can result in aberrations, for
example aberrations corresponding to a meniscus of the tear and a
far sighted portion of the cornea. As variation in epithelial
healing among individuals can be observed, the epithelial defect of
at least some individuals can be present at 2 and 3 days post-op,
with corresponding aberrations.
[0134] FIG. 1-1C shows an ablated eye when the epithelium has
regenerated following refractive surgery resulting in an increased
epithelial thickness centrally when the epithelium has regenerated,
for example at about 3 days post-op. The regenerating epithelium
may have an irregularity 12I, for example corresponding to an
increased elevation of an inner portion of the epithelium near the
center of the ablation, for example. Work in relation to
embodiments as described herein suggests that the natural
regeneration of the epithelium can provide an inner portion having
an increased central elevation with optical power that may
correspond to about 1 to 3 Diopters of additional optical power.
The regenerating epithelium comprises a thickness profile 12RP
extending along the surface of Bowman's membrane 14 and the
ablation 20. With PRK the thickness profile 12RP of the epithelium
can regenerate for at least one week, for example one month, such
that vision can be degraded when the thickness profile 12RP of the
epithelium regenerates, and PRK surgery of the cornea can be
combined in accordance with embodiments described herein so as to
improve vision.
[0135] In many embodiments as described herein, irregularities of
the cornea are decreased when the epithelium regenerates so as to
provide one or more of improved vision or comfort. The coverings as
described herein can be configured so as to decrease an effect on
vision of corneal irregularity 12I, decrease the height profile of
irregularity 12I, decrease transfer of irregularity 12I to an
anterior surface of the covering, smooth irregularity 12I with the
covering, regenerate epithelium 12 such that irregularity 12I is
decreased, or combinations thereof. In many embodiments, the
covering 100 as described herein can be placed on the eye such that
a smooth layer 12S of regenerated epithelium 12R substantially
covers the ablated profile so as to provide improved vision sooner
than would occur without covering, for example at about 3 to 4 days
post-op with PRK. In many embodiments, the covering can provide an
environment 100E as described herein so as to guide epithelial
regeneration and smooth the regenerated epithelium.
[0136] In many embodiments, the cornea 10 of an eye 2 has an
epithelial defect 11 following refractive surgery such as PRK, and
a covering 100 positioned over the epithelial defect 11.
[0137] FIG. 1-2A shows a covering 100 positioned on cornea 10 an
eye 2 having an epithelial defect 11, in which the covering abuts
the cornea to seal the cornea. The covering may comprise a curved
body, for example a curved contact lens body shaped to fit the
cornea.
[0138] The covering 100 can be sized to cover the ablated profile
and epithelial defect. The inner portion 110 comprises a dimension
across 102 that can be sized to extend across a majority of the
ablation, and the outer portion 120 comprises a dimension across
104 sized to extend across at least the epithelial defect and
contact the epithelium on opposite sides of the defect.
[0139] The dimension 102 extending across a majority of the
ablation may extend about 6 to 8 mm, for example, and may be sized
larger than the ablation. The dimension 104 may comprise about 12
to 14 mm across, for example so as to extend to the limbus and can
be sized to the limbus of the patient for example. Work in relation
to embodiments suggests that the covering sized to extend to the
limbus and circumferentially around the limbus can be centered on
the cornea. The covering may extend such that the outer rim of the
covering contacts the conjunctiva disposed above the sclera
peripheral to the limbus, for example, and that such configurations
may center the lens on the cornea, for example.
[0140] The thickness of the covering can be sized and shaped in
many ways. The inner portion 110 of the covering comprises a
thickness 106 and the outer portion 120 of the covering comprises a
thickness 108. The thickness 106 of the inner portion may comprise
a substantially uniform thickness such that the inner portion
comprises an optical power of no more than about +/-1D prior to
placement on the eye, for example when held in front of the eye and
separated from the cornea by a distance. Alternatively, the
thickness of the inner portion may vary so as comprise optical
power, for example optical power to correct vision of the
patient.
[0141] FIG. 1-2B shows a smooth layer 12S of regenerated epithelium
12R substantially covering an ablated profile. The environment 100E
is configured to guide epithelial regeneration and smooth the
regenerated epithelium. The regenerating epithelium comprises a
thickness profile 12RP.
[0142] The epithelium grows centripetally from circumscribing
boundary 12E toward the center of ablated profile 20 to cover the
exposed stroma, as indicated by arrows 30.
[0143] The covering 100 may comprise an inner portion 110 and an
outer portion 120. The outer portion 120 can be configured to form
a seal 100S with the cornea near the edge of the ablation and the
epithelial defect, for example with a soft conformable material
such as silicone or silicone hydrogel. The inner portion 110 is
positioned over the pupil and configured for the patient to see,
and may comprise a rigidity greater than the outer portion, so as
to smooth irregularities of the epithelium when the cornea heals.
Alternatively, the inner portion may comprise a rigidity equal to
or less than the rigidity of the outer portion as well. For
example, the inner portion may comprise silicone and the outer
portion may comprise silicone, and the inner portion may comprise
one or more of a more rigid silicone or a greater thickness such
that the inner portion can be more rigid than the outer portion so
as to smooth the epithelium. Although the inner portion can be more
rigid than the outer portion, the inner portion is sufficiently
soft, flexible and conformable so as to conform at least partially
to the ablated profile 20 in the stroma, such that the patient
receives the benefit of the vision correction with the ablation
profile 20 when the patient looks through the inner portion and the
inner portion smoothes the epithelium. Work in relation to
embodiments of the present invention suggests that the regenerating
epithelium is softer than the underlying stroma of ablation profile
20, such that the inner portion can be configured to conform to the
shape of the ablation profile 20 when the inner portion smoothes
the epithelium disposed under the inner portion.
[0144] The covering 100 may comprise one or more of many optically
clear materials, for example synthetic materials or natural
material such collagen based materials, and combinations thereof,
such as described in U.S. patent application Ser. No. 12/384,659,
filed Apr. 6, 2009, entitled "Therapeutic Device for Pain
Management and Vision", U.S. Pub. No. US 2010-0036488 A1, published
on 11 Feb. 2010. For example, the lens material may comprise a
naturally occurring material, such as collagen based material.
Alternatively or in combination, the lens material may comprise a
known synthetic material, for example hydroxyethyl methacrylate
(HEMA) hydrogel, hydrogel, silicone, for example hydrated silicone
and derivatives thereof. For example, the optically clear material
may comprise one or more of silicone, silicone hydrogel, silicone
comprising resin, silicone comprising silicate, acrylate,
orcollagen. The cured silicone may comprise silicone that is
two-part heat cured and RTV (room temperature vulcanized). For
example, polydimethyl siloxane such as NuSil, or poly(dimethyl)
(diphenyl) siloxane may be used to mold the covering, for example
with less than 10% water content so as to increase oxygen diffusion
through the covering. The covering 100 may comprise
perfluoropolyethers or fluorofocal. The lens material can be
elastic, for example a stretchable elastic material such as
silicone, such that the lens can seal the cornea. The lens material
can be cured with a hardness and size and shape such that the
covering comprises a modulus within a range from about 4 to about
20 MPa. The material may comprise, for example, silicone elastomer
having optically clear silicate disposed therein and a water
content of no more than about 10%, for example no more than about
5%, such that the lens covering has a very high Dk exceeding 150,
and the silicone lens comprising silicate can be treated to provide
a wettable surface. The lens may comprise hydrogel, for example
silicone hydrogel, and can be formed with a water content within a
range from about 5% to about 35% and a modulus within a range from
about 4 to about 20 MPa, such that the covering conforms at least
partially to the ablated stroma.
[0145] The covering may comprise silicone or silicone hydrogel
having a low ionoporosity such that covering seals to the cornea.
For example, covering may comprise silicone hydrogel comprising a
low ion permeability, and the range of water can be from about 5%
to about 35%, such that the Dk is 100 or more. The low ion
permeability may comprise an Ionoton Ion Permeability Coefficient
of no more than about 0.25.times.10-3 cm2/sec so as to seal the
cornea, for example no more than about 0.08.times.10-3 cm2/sec. The
low ion permeability comprises an Ionoton Ion Permeability
Coefficient of no more than about 2.6.times.10-6 mm2/min to seal
the cornea, for example no more than about 1.5.times.10-6
mm2/min.
[0146] The covering 100 may comprise a wettable surface coating 134
disposed on at least the upper side of the covering, such that the
tear film of the patient is smooth over the covering and the
patient can see. The wettable surface coating may comprise a
lubricious coating for patient comfort, for example to lubricate
the eye when the patient blinks. The wettable coating may comprise
a contact angle no more than about 80 degrees. For example, the
coating may comprise a contact angle no more than about 70 degrees,
and the contact angle can be within a range from about 55 to 65
degrees to provide a surface with a smooth tear layer for vision.
For example, the wettable coating can be disposed of both an upper
surface and a lower surface of the covering. Alternatively, the
lower surface may comprise a hydrophobic surface material and the
lower hydrophobic surface may comprise the inner portion 110 and
the outer portion 120. At least the outer portion 120 may comprise
a lower surface composed of a sticky, tacky material, for example a
hydrophobic material. The inner portion may also comprise the lower
surface comprised of the sticky, tacky, hydrophobic material. The
upper surface may comprise the wettable coating extending over at
least the inner portion 110.
[0147] The wettable coating may comprise one or more of many
materials. For example, the wettable coating may comprise
polyethylene glycol (PEG), and the PEG coating can be disposed on
Parylene.TM.. Alternatively, the wettable coating may comprise a
plasma coating, and the plasma coating comprise a luminous chemical
vapor deposition (LCVD) film. For example, the plasma coating
comprises at least one of ahydrocarbon, for example CH4, O2 or
fluorine containing hydrocarbon, for example CF4 coating.
Alternatively or in combination, the wettable coating may comprise
a polyethylene glycol (PEG) coating or 2-hydroxyethylmethacrylate
(HEMA). For example, the wettable coating may comprise HEMA
disposed on a Parylene.TM. coating, or the wettable coating may
comprise N-vinylpyrrolidone (NVP) disposed on a Parylene.TM.
coating.
[0148] The covering 100 may comprise a lower surface corresponding
to one or more of many suitable shapes to fit the covering to the
cornea. For example, the lower surface of the covering may
correspond to base radius of curvature. With post ablation corneas,
the covering may conform substantially to the cornea. The covering
may comprise a second curve in combination with a first curve, such
that the lower surface comprises a bicurve surface. Alternatively,
the lower surface may correspond to an aspheric surface. For
example, an aspheric surface may comprise an oblate shape and conic
constant to fit a post PRK eye. Also, it may be helpful to fit the
covering to the cornea, for example with selection of one covering
from a plurality of sizes.
[0149] FIG. 1A shows the covering 100 having the thickness 108 of
the outer portion sized such that the outer portion can conform to
the epithelium. The thickness of the outer portion can be
substantially constant, or may vary as described herein below.
[0150] FIG. 1A1 shows covering 100 positioned on an eye and
blinking of the eye. An upper lid and a lower lid can blink over
the eye. Work in relation to embodiments suggests that the upper
lid can exert a downward movement 20 and that the lower lid can
exert an upper movement 22 on the eye. The downward movement 20 can
be greater than the upper movement 22. The wettable coating
material as described herein can decrease force and movement
transferred from the lids to the covering so as to inhibit motion
of the covering. The downward movement 20 greater than the upward
movement 22 can affect epithelial growth near the perimeter of
covering 100.
[0151] FIG. 1B1 shows covering 100 as in FIG. 1-2A prior to
placement on the cornea. The covering 100 may comprise a base
radius R1 of curvature, and the base radius of curvature may be
slightly shorter than the ablated cornea such that the covering can
be steeper than the cornea prior to placement on the cornea. The
covering 100 comprises a first configuration 100C1 prior to
placement on the cornea.
[0152] The base radius R1 can be sized to the cornea in many ways.
For example, base radius R1 may have a radius corresponding to the
outer unablated portion of the cornea. Alternatively or in
combination, the base radius R1 may have a radius corresponding to
the post ablated eye.
[0153] The covering 100 may comprise a modulus within a range from
about 4 MPa to about 20 MPa, such that central portion can conform
at least partially to the ablated stroma and so that the covering
can smooth corneal irregularities and stromal irregularities of the
ablated cornea. The covering may comprise an elastomeric
stretchable material such that the covering can stretch to fit the
cornea, for example. The covering having the modulus within a range
from about 4 MPa to about 20 MPa can be formed in many ways as
described herein. For example, the covering may comprise a single
piece of material having a substantially uniform thickness
extending across the ablated cornea and at least a portion of the
unablated cornea, and the single piece of material may comprise an
elastic material such as a silicone elastomer or a hydrogel.
Alternatively, the covering may comprise a single piece of material
having a non-uniform thickness extending across the ablated cornea
and at least a portion of the unablated cornea. The covering can be
shaped in many ways and may comprise a single piece of one
material, or may comprise a single piece composed to two similar
materials, or may comprise a plurality of materials joined
together.
[0154] The covering 100 may comprise one or more outer portions
extending outside the inner central portion, and these outer
portions may seal the cornea when the inner portion conforms at
least partially to the ablated stroma. For example, the covering
100 may comprise outer portion additional shapes disposed outward
from a central portion as described herein. For example, the
covering may comprise a bicurve having a second radius of curvature
disposed peripheral to the inner radius R1 of curvature to fit the
unablated portion of the cornea. For example, the second and outer
radius of curvature may comprise a shorter radius of curvature when
the central portion is treated for myopia. The covering may
comprise a third radius of curvature longer than the second radius
of curvature so as to fit the sclera under the conjunctiva. The
covering may comprise an oblate shape to fit the ablated and
non-ablated portions of the cornea, and the covering may extend
over the sclera with an outer portion, for example.
[0155] FIG. 1B2 shows the covering as in FIG. 1B1 conforming to
ablated stromal tissue and smoothing the epithelium over the
ablated stroma. The cornea comprises an ablated surface 20 to
correct vision that may have a corresponding radius of curvature,
for example radius R2. The ablated profile 20 may comprise
additional, alternative, or combinational shapes with those
corresponding to radius R2, such as aberrations ablated into the
cornea to correct aberrations of the eye and astigmatism ablated
into the cornea, and the inner portion 110 of covering 100 can
conform to these ablated profiles of the cornea such that the
patient can receive the benefit of the ablative vision correction
when the covering is positioned on the cornea. For example, the
cornea ablation profile 20 may correspond to radius of curvature
R2, and the inner portion 110 can flatten from configuration 100C1
corresponding to radius of curvature R1 prior to placement to a
second configuration 100C2 corresponding substantially to the
ablated profile 20, such the patient can see with the benefit of
ablation profile 20. For example, the second configuration 100C2
can comprise a conforming radius of curvature R12 that corresponds
substantially to radius of curvature R2. The profile corresponding
to the first configuration 100C1 of the covering 100 is shown
positioned over cornea 10 to illustrate the change in profile of
the covering from configuration 100C1 prior to placement to
conforming second configuration 100C2 of the covering 100 when
positioned on the cornea.
[0156] The conformable covering 100 comprises sufficient rigidity
so as to smooth the epithelium when covering 100 is positioned on
the cornea over the ablation profile 20. The epithelium comprises a
peripheral thickness 12T that may correspond substantially to a
thickness of the epithelium prior to debridement of the epithelium
to ablate the cornea. The epithelium also comprises regenerating
epithelium 12R disposed over the ablation profile 20. The covering
100 can smooth the epithelium 12R when conforming to the cornea in
the second configuration 100C2. For example, irregularities 12I of
the regenerating epithelium 12R disposed over the ablation can be
smoothed when the epithelium regenerates along the inner portion of
covering 100, such that the irregularities 12I of the regenerating
epithelium 12R are thinner than the thickness 12T of the peripheral
epithelium.
[0157] Work in relation to the embodiments as described herein
indicates that an at least partially conformable covering having a
modulus within a range from about 4 MPa to about 20 MPa can conform
at least partially to the ablated stroma and smooth irregularities
of the epithelium and stroma so as to improve vision as described
herein. The covering having the modulus within the range from about
4 MPa to about 20 MPa can be formed in many ways as described
herein.
[0158] The conformable covering 100 may comprise a perimeter 120P
with rigidity sufficient to indent the epithelium along at least a
portion of the perimeter so as to seal the cornea with seal 100S.
The portion 12C of the epithelium 12 can extend over the perimeter
120P of the covering 100.
[0159] FIG. 1B2A shows a covering as in FIG. 1B2 forming an
indentation 12IT in the epithelium such that the epithelium 12
extends over at least a portion of the perimeter 120P of the
covering. The covering forms indentation 12IT in the epithelium
such that the epithelium comprises an indentation thickness 12T
that is less than an outer thickness of the epithelium 12. The
indentation of the epithelium with the covering can help to seal
the cornea with the perimeter.
[0160] FIG. 1B2B shows a covering as in FIG. 1B2 forming
indentation 12IT in the epithelium. The covering forms indentation
12IT in the epithelium such that the epithelium comprises an
indentation thickness 12T that is less than an outer thickness of
the epithelium 12T. The indentation of the epithelium with the
covering can help to seal the cornea with the perimeter.
[0161] Work in relation to embodiments described herein suggests
the indentation of the covering can vary radially around the eye of
the patient, in accordance with orientation of the covering on the
eye when the covering comprises a substantially constant rigidity
of the outer portion, for example a substantially constant rigidity
around the perimeter. The inferior portion of the covering may
comprise a greater amount of epithelial covering over the perimeter
than the superior portion of the covering. For example, FIG. 1B2A
may correspond to a first portion of covering 100 at an inferior
location of the cornea and FIG. 1B2B may correspond to a second
portion of the covering at a superior location of the cornea. Work
in relation to embodiments also suggests that there may be
variability in covering of the perimeter with the epithelium
between the nasal portion of the perimeter, and the temporal
portion of the perimeter, although both the nasal and temporal
locations can comprise covering intermediate and between the more
extensive covering of the inferior portion and the less extensive
covering of the superior portion of the perimeter.
[0162] FIG. 1B2C shows a covering abutting the cornea to seal the
cornea without forming a substantial indentation in the epithelium.
The covering may comprise a chamfer to contact and seal the cornea.
The rigidity of the outer portion can be determined based on the
thickness of the outer portion of the covering, hardness of the
material, and chamfer angle so as to contact the epithelium to seal
the cornea without substantial deformation of the epithelium.
[0163] The covering may comprise a non-uniform rigidity around the
outer portion of the covering comprising the perimeter. For
example, the covering may comprise a superior portion corresponding
to a superior location on the cornea and an inferior portion
corresponding to an inferior location on the cornea. The superior
portion may comprise a rigidity less than the inferior portion. For
example, the superior portion may comprise the rigidity less than
the inferior portion, such that deformation of the epithelium is
inhibited when the perimeter abuts the cornea is sealed.
Alternatively, the superior portion may comprise the rigidity less
than the inferior portion such the deformation of the epithelium
with the covering comprises a substantially constant amount around
the perimeter, for example a deformation of no more than about 10
um, for example 5 um.
[0164] FIG. 1C shows a therapeutic covering as in FIG. 1-2A
comprising a covering molded with a homogeneous material, in which
the outer portion comprises a thickness configured to conform with
the cornea and in which the inner portion 110 comprises thickness
configured to smooth the epithelium and conform to the ablated
profile 20. The outer portion 120 may comprise a thickness of no
more than about 100 microns. For example, the outer portion 120 may
comprise a thickness of about 50 microns at the boundary with the
inner portion 110, and linearly taper from 50 microns at the
boundary with the inner portion to about 20 microns at the
periphery of the outer portion 120. The inner portion 110 may
comprise a thickness of no more than about 250 microns, for example
no more than about 200 microns. For example, the inner portion may
comprise a thickness of about 100 microns. For example, the
thickness of each of the inner portion and the outer portion may
comprise no more than about 50 microns so as to provide substantial
oxygen transport and epithelial regeneration. Many materials can be
used as described herein, and the covering may comprise one or more
materials. For example, the covering may comprise a single piece of
material such as silicone having a water content within a range
from about 0.1% to about 10%, for example no more than about 1%,
and a hardness Shore A durometer parameter within a range from
about 5 to about 90, for example within a range from about 40 to
about 85.
[0165] FIG. 1C1 shows a covering 100 having an inner portion 110
comprising an inner thickness and an inner material 110M and an
outer portion 120 comprising an outer thickness and an outer
material 120M, in which the inner thickness is greater than the
outer thickness. The inner material 110M may comprise many
materials and may comprise an optically clear silicone, for example
silicone with resin. The inner material may comprise silicone
positioned in a mold with the outer portion 120 formed around the
inner portion. The inner portion may comprise a hardness similar to
the outer portion. The outer material 120M of the outer portion 120
may comprise a material similar to the inner portion. For example,
the outer material 120M may comprise silicone and the inner
material 110M may comprise silicone. This use of similar materials
on the inner and outer portions can improve adhesion of the inner
portion to the outer portion. The outer material 120M may extend
along the inner portion 110, for example along the underside of the
inner portion 110, such that the inner material 110M is held in a
pocket of the outer material 120M. Alternatively, the inner
material 110M may extend substantially across the thickness of the
inner portion 110, such that the outer material 120M comprises a
substantially annular shape with the inner material 110M comprising
a disc shaped portion disposed within the annulus and extending
substantially from the upper surface coating to the lower surface
coating when present.
[0166] FIG. 1C1A shows a covering as in FIG. 1C1 adhered to the
cornea with a smooth upper surface, and a lower surface conforming
to irregularity of the cornea, for example an irregularity
comprising a central island 10CI of the ablated stroma. The central
island 10CI may comprise an outward protrusion in the ablated
profile of the stroma at least about 1 micron outward and about 2.5
mm across, for example. The upper surface may comprise a
substantially rigid material for vision correction, and the lower
surface may comprise a soft material so as to deflect to
irregularities of the cornea when the upper surface provides
optical correction. For example, the lower surface may comprise an
indentation 110I when positioned on the irregularity of the cornea.
Although the lower surface comprising the soft material can deflect
to correspond to the ablation profile 20, the upper surface
comprising the rigid material may comprise a predetermined
curvature selected by a health care provider so as to fit the
ablation profile and correspond to the refractive correction of the
patient so as to provide vision correction.
[0167] FIG. 1C2 shows a covering as in FIGS. 1-2A to 1B2 having
inner portion 110 comprising an inner thickness and inner material
110M and outer portion 120 comprising an outer thickness and outer
material 120M, in which the inner thickness can be greater than the
outer thickness and the outer material 120M extends around the
inner material 110M. The covering 100 may comprise at least a
bicurve covering having at least a second radius R1B. The inner
portion 110M may comprise three layers of material, a first layer
100L1 of a first material 110M1, a second layer 100L2 of a second
material 110M2 and a third layer 100L3 of a third material 110M3.
The second material 110M2 may comprise a rigid material, for
example one or more of a rigid gas permeable material, a rigid
silicone, or a rigid silicon acrylate. The first material 110M1 and
the third material 110M3 may comprise a soft material, for example
a soft elastomer or soft hydrogel such as one or more of a soft
optically clear silicone or a soft silicone hydrogel. The first
material, the third material, and the outer material 120M may
comprise similar materials, such that the second layer of rigid
material 110M2 is encapsulated with the first soft material 110M1,
the third soft material 110M3 and on the perimeter with the soft
outer material 120M. In many embodiments, the second rigid material
110M2 comprises a material similar to each of the first material
110M1, the third material 110M3 and the outer material 120M, for
example each may comprise silicone, such that the corresponding
portions of the covering 100 can be bonded together with the
silicone similar to silicone elastomer material, for example. In
many embodiments, the covering 100 can be formed in a mold with
rigid second material 110M2 placed in the mold and encapsulated
within a single piece of material comprising first material 110M1,
third material 110M3 and outer material 120M, such that first
material 110M1, third material 110M3 and outer material 120M
comprise substantially the same material, for example silicone
elastomer. The rigid second material 110M2 may comprise silicone
bonded to each of first material 110M1, third material 110M3 and
the outer material 120M, for example with curing such that first
material 110M1, third material 110M3 and outer material 120M
comprise the same soft silicone material bonded to the second
material 110M2 comprising rigid silicone.
[0168] The soft material comprising soft outer portion 120 composed
of soft material 120M, first layer 100L1 composed of soft material
110M1 and third layer 100L3 composed of soft material 120M3 can
provide improved comfort and healing for the patient. The soft
material can deflect, bend or indent so as to conform at least
partially to the tissue of the eye when the rigid portion
comprising rigid material 110M2 corrects vision of the patient. The
dimension 102 across inner portion 110 can be sized to
substantially cover the ablation zone and slightly smaller than the
ablation dimensions, such as ablation diameter 20D, so that the
epithelium can grow inward and contact the layer 100L1110L1 of soft
first material 110M1 without substantial disruption from the rigid
material 120M2 when the inner portion 110M corrects vision with the
layer of rigid material 110M2. The eyelid can also move over the
third layer 100L3 for improved comfort. The soft first material
110M1 and soft third material 110M3 may comprise soft elastomer or
soft hydrogel, for example, and may each comprise the same material
so as to encapsulate the second layer 100L2 of rigid second
material 110M2.
[0169] The soft material comprising soft outer portion 120 composed
of soft material 120M, first layer 100L1 composed of soft material
110M1 and third layer 100L3 composed of soft material 110M3 can
have a modulus within a range from about 1 to 20 MPa, for example
within a range from about 1 to 5 MPa.
[0170] The material inner material 120M and 110M2 of second layer
100L2 can have a modulus within a range from about 5 to about 35 or
more, for example as set forth in Table A below. For example, when
material 120M comprises silicone elastomer or layer 100L2 of
material 110M2 comprises silicone elastomer, the modulus can be
within a range from about 5 to about 35 MPa, for example within a
range from about 20 to about 35 MPa.
[0171] The layers of covering 100 can comprise dimensions so as to
provide therapeutic benefit when placed on eye 2. The thickness of
layer 100L1 can be from about 5 um to about 50 um, for example,
within a range from about 10-30 um, such that the layer 100L1 can
provide a soft at least partially conformable material to receive
the lens. The middle layer 100L2 can be from about 20 um to about
150 um, for example, and material 110M2 can have a modulus greater
than first material 110M1 of first layer 100L1, so as to deflect
the epithelium of the eye when the middle layer is deflected. The
third layer 100L3 can be within a range from about 5 um to 50 um,
for example within a range from about 10 um to about 30 um, and can
cover second layer 100L2 so as to retain the second layer in the
inner portion 110 of the covering 100.
[0172] FIG. 1C2A shows a covering as in FIG. 1C1 placed on the
cornea with a smooth upper surface and a lower surface conforming
to irregularity of the cornea near the edge of the ablation. As the
epithelium can be about 50 um thick, in many embodiments the
dimension 102 is sized so as to cover substantially the ablated
cornea for vision correction and smaller than the ablation zone,
such that the outer portion 120 can conform at least partially to
the epithelium. The outer portion 120 may extend to the sclera, and
comprise a tri-curve covering 100 as described herein, with the
inner portion 110 having first layer 100L1 of first material 110M1,
second layer 100L2 of second material 110M2, and third layer 100L3
of third material 110M3.
[0173] FIG. 1C2A1 shows a covering having a layer of hydrogel
material on a posterior surface of the covering. The covering 100
may comprise a wettable surface coating 134 disposed on at least
the upper side of the covering as described herein. The layer of
hydrogel material may comprise an inner portion of the layer of
hydrogel material 110MHG and an outer portion of the layer of
hydrogel material 120MHG. The layer of hydrogel material extends to
the fenestration so as to couple the hydrogel material to the
fenestration. The hydrogel material can be coupled to the
fenestration in many ways. For example, the layer of hydrogel
material may cover the fenestration, or the fenestration 100F may
extend through the hydrogel material. The fenestration 100F
extending through the layer of hydrogel material can encourage
pumping of the tear liquid as described herein. Alternatively or in
combination, the layer of hydrogel material covering a posterior
surface of the fenestration 100F to couple the fenestration 100F to
the hydrogel layer may encourage movement of a therapeutic agent
along the hydrogel layer toward a central portion of the cornea for
example. The hydrogel may extend along a deflectable portion of the
covering so as to exert at least some pressure on the hydrogel
layer to encourage movement of one or more of tear liquid or the
therapeutic agent along the hydrogel layer when the patient blinks,
for example.
[0174] The hydrogel layer as described herein may encourage
regeneration of the epithelium and may provide a soft surface to
contact the epithelium regenerating over the ablation so as to
encourage epithelial regeneration under the optical component as
described herein, and the optical component can resist deformation
so as to protect the epithelium and provide an environment to
encourage regeneration of the epithelium.
[0175] The hydrogel material may comprise one or more of the
hydrogel materials as described herein. The hydrogel material
extending along the lower surface can increase comfort of the
covering when placed on the eye. The hydrogel material may comprise
a substantially uniform thickness within a range from about 1 um to
about 100 um, for example from about 2 um to about 50 um and in
many embodiments within a range from about 5 um to about 20 um. The
hydrogel material extending along the posterior surface may
comprise on or more of the hydrogel materials as described herein
combined with one or more of materials 110M, 110M1, 110M2, 110M3 or
120M as described herein. For example the one or more of materials
110M, 110M1, 110M2, 110M3 or 120M may comprise silicone such as
silicone elastomer comprising siloxane, and the hydrogel may
comprise a hydrogel such as silicone hydrogel material as described
herein.
[0176] FIG. 1C2A shows a covering having a layer of hydrogel
material on a posterior surface of the covering. The covering 100
may comprise a wettable surface coating 134 disposed on at least
the upper side of the covering as described herein. The layer of
hydrogel material may comprise an inner portion of the layer of
hydrogel material 110MHG and an outer portion of the layer of
hydrogel material 120MHG. The layer of hydrogel material extends to
the fenestration so as to couple the hydrogel material to the
fenestration. The hydrogel material can be coupled to the
fenestration in many ways. For example, the layer of hydrogel
material may cover the fenestration, or the fenestration 100F may
extend through the hydrogel material. The fenestration 100F
extending through the layer of hydrogel material can encourage
pumping of the tear liquid as described herein. Alternatively or in
combination, the layer of hydrogel material covering a posterior
surface of the fenestration 100F to couple the fenestration 100F to
the hydrogel layer may encourage movement of a therapeutic agent
along the hydrogel layer toward a central portion of the cornea for
example. The hydrogel may extend along a deflectable portion of the
covering so as to exert at least some pressure on the hydrogel
layer to encourage movement of one or more of tear liquid or the
therapeutic agent along the hydrogel layer when the patient blinks,
for example.
[0177] The hydrogel layer as described herein may encourage
regeneration of the epithelium and may provide a soft surface to
contact the epithelium regenerating over the ablation so as to
encourage epithelial regeneration under the optical component as
described herein, and the optical component can resist deformation
so as to protect the epithelium and provide an environment to
encourage regeneration of the epithelium.
[0178] The hydrogel material may comprise one or more of the
hydrogel materials as described herein. The hydrogel material
extending along the lower surface can increase comfort of the
covering when placed on the eye. The hydrogel material may comprise
a substantially uniform thickness within a range from about 1 um to
about 100 um, for example from about 2 um to about 50 um and in
many embodiments within a range from about 5 um to about 20 um. The
hydrogel material extending along the posterior surface may
comprise on or more of the hydrogel materials as described herein
combined with one or more of materials 110M, 110M1, 110M2, 110M3 or
120M as described herein. For example the one or more of materials
110M, 110M1, 110M2, 110M3 or 120M may comprise silicone such as
silicone elastomer comprising siloxane, and the hydrogel may
comprise a hydrogel such as silicone hydrogel material as described
herein.
[0179] FIG. 1C2B shows a covering having a layer of hydrogel
material on a posterior surface of the covering extending less than
a maximum distance across the covering such that end portions of
the covering are configured to engage the epithelium of the eye
away from the hydrogel layer and inhibit movement of the covering
when placed on the eye. In many embodiments, the material 120M can
couple to the surface of the eye, for example the epithelium so as
to inhibit movement of the covering. The material 120M may comprise
a sticky tacky hydrophobic material such as silicone to engage the
epithelium to inhibit movement, and the material 120M may be coated
with one or more coatings as described herein, for example with
vapor deposition. The hydrogel material can be coupled to the
fenestration in many ways. For example, the layer of hydrogel
material may cover the fenestration, or the fenestration 100F may
extend through the hydrogel material.
[0180] FIG. 1C2C shows a covering 100 having an annular layer of
hydrogel material 120MHG on a posterior surface of the covering
such that an inner portion of the covering contacts the cornea away
from the hydrogel layer and an outer portion of the covering
contacts the cornea away from the covering when placed on the eye.
Work in relation to embodiments suggests that the annular hydrogel
layer can provide an environment to encourage growth of the
epithelium along the posterior surface of inner material 110M1 as
described herein, and the lower surface of material 110M1 can be
coated with a material having a thickness less than the hydrogel,
for example.
[0181] FIG. 1C3 shows a shows a covering having a tricurve profile
to fit sclera with slopes of the curved profiles aligned so as to
inhibit ridges at the boundaries of the curved portions as in FIG.
1B2 and having a layer of hydrogel material 120MHG on a lower
surface. The hydrogel material 120M may extend substantially across
the posterior surface of the covering. The covering may extend
along the lower surface a distance less than a distance across the
covering so as to provide a portion of the covering without the
hydrogel to engage the eye, for example the epithelium of the eye
that may comprise one or more of the corneal epithelium or the
conjunctival epithelium. Alternatively, the covering may extend
substantially along the posterior surface of the covering
corresponding to the distance across the covering so as to provide
the hydrogel covering over the outer portion of the covering that
engages the eye.
[0182] FIG. 1C4 shows a plan view covering having a tricurve
profile to fit the cornea, limbus and sclera with slopes of the
curved profiles aligned so as to inhibit ridges at the boundaries
of the curved portions and having a hydrogel material on a lower
surface extending less than a maximum distance across the covering
to engage the conjunctiva with the covering away from the hydrogel
material. Alternatively, the covering may extend substantially
along the posterior surface of the covering corresponding to the
distance across the covering so as to provide the hydrogel covering
over the outer portion of the covering that engages the eye. The
hydrogel covering may comprise an annular shape extending along the
lower surface as described herein.
[0183] FIG. 105 shows a fenestration 100F having a posterior end
100FPE covered with a layer of hydrogel material 29MHG extending
along the posterior surface of the covering 100, in accordance with
embodiments of the present invention;
[0184] FIG. 106 shows a fenestration 100F extending through a layer
of hydrogel material 120MHG extending along the posterior surface
of the covering 100, in accordance with embodiments of the present
invention;
[0185] FIG. 1D shows atherapeutic covering 100 comprising a first
inner material 110M and a second outer material 120M, in which the
outer portion 120 comprises a hardness configured to conform with
epithelium of the cornea and in which the inner portion 110
comprises second hardness configured to smooth the epithelium and
conform to the ablated profile 20. The outer material 120M may
comprise many materials as herein. The Shore A hardness of each of
the inner portion and the outer portion can be within a range from
about 5 to about 90. For example, the outer material 120M may
comprise silicone having a hardness Shore A durometer parameter
from about 20 to about 50, for example from about 20 to about 40,
and the inner material 110M may comprise silicone having a hardness
durometer parameter from about 40 to about 90, for example from
about 50 to about 90. The outer portion comprises a perimeter 120P,
and the perimeter may comprise a peripheral and circumferential
edge structure to abut the epithelium to form the seal with the
epithelium, for example when the base radius of the covering is
less than the cornea. The peripheral and circumferential edge
structure can be shaped in many ways to define an edge extending
around the perimeter to abut the epithelium, for example with one
or more of a taper of the edge portion extending to the perimeter,
a bevel of the edge portion extending to the perimeter or a chamfer
of the edge portion extending to the perimeter. The inner portion
110 may comprise inner thickness and inner material 110M and the
outer portion 120 may comprise an outer thickness and outer
material 120M, in which the inner thickness is substantially
similar to the outer thickness.
[0186] The peripheral edge structure to abut the epithelium can be
used with many configurations of the inner portion as described
herein. For example, the inner portion may comprise an RGP lens
material having a lower rigid surface to contact and smooth the
cornea and an upper rigid optical surface. Alternatively, the inner
portion may conform to the cornea as described herein. The outer
portion may comprise a skirt, and the skirt may comprise the
peripheral edge structure to abut and seal the cornea, such as the
chamfer. The rigidity of the outer portion comprising the edge
structure can be determined to seal the cornea with one or more of
hardness and thickness, as described herein.
[0187] FIGS. 1E and 1F show top and side views, respectively, of
covering 100 comprising inner portion 110, outer portion 120, and a
peripheral rim portion 140 disposed around outer portion 120. The
peripheral portion 140 can be more rigid than outer portion 120.
Work in relation to embodiments suggests that in some instances the
lower sticky, tacky surface of outer portion 120 can stick to
itself during deployment onto the eye, and the peripheral portion
140 can improve handling when the covering is placed on the eye.
The covering may comprise a single piece of material or may
comprise multiple pieces adhered together, for example molded
together. For example, the covering may comprise an inner thickness
of inner portion 110 and an outer thickness of outer portion 120,
in which the inner thickness is greater than the outer thickness.
The peripheral portion 140 may comprise a thickness, and the
thickness of the peripheral portion 140 can be greater than the
thickness of outer portion 120 such that the peripheral portion 140
is more rigid than the outer portion 120. The thickness of the
inner portion 110 and the thickness of the peripheral portion 140
can be substantially similar, and these portions may comprise
substantially the same thickness and rigidity.
[0188] FIG. 1G shows covering 100 comprising inner portion 110 and
outer portion 120, such that outer portion 120 comprises a taper
120T of thickness 108 extending between the perimeter of the inner
portion 110 and the perimeter of the outer portion 120. The taper
may comprise a substantially linear change in thickness 108
extending between the perimeter of the inner portion and the
perimeter of the outer portion.
[0189] FIG. 1G1 shows a covering 100 comprising inner portion 110
and an outer portion 120 comprising the taper as in FIG. 1G, and an
outer rim or flange 120F of substantially uniform thickness
peripheral to the taper 120T. The outer taper may extend from the
dimension across 102 of the inner portion 110 to the dimension
across 154A that is less than the dimension across 104 of the outer
portion. The rim of substantially uniform thickness may comprise an
annular shape having a thickness within a range from about 10 um
thick to about 40 um thick, and may comprise a width 154B within a
range from about 0.05 to about 0.8 mm, for example about 0.5 mm.
The rim, for example flange 120F, may comprise a thickness of no
more than about 50 um, such that the flange comprises a thickness
no more than the epithelium.
[0190] The covering 100 can be dimensioned in many ways. The total
diameter across can be from about 6 mm to about 12 mm, for example
about 10 mm. The inner portion may comprise a diameter within a
range from about 4 mm to 8 mm, for example about 6 mm. The annular
rim comprising flange 120F can extend around the perimeter of the
covering with a thickness of about within a range from about 5 um
to about 50 um, for example about 35 um. The annular rim comprising
flange 120F may comprise an inner diameter of within a range from
about 5 mm to about 11 mm, for example about 9 mm and an outer
diameter within a range from about 6 mm to about 12 mm, for example
about 10 mm and corresponding to the perimeter of the covering. The
annular rim may comprise a width of within a range from about 0.1
mm to about 1 mm, for example 0.5 mm, extending circumferentially
around the covering. The outer portion 120 may comprise the rim
with flange 120F and a taper 120T that extended from inner portion
110 to the rim comprising perimeter 120P. The taper in thickness
can be substantially uniform between the outer diameter of the
inner portion and the inner diameter of the rim, and the boundaries
of the taper can be rounded and smoothed near the inner portion and
the rim. The central portion may comprise a substantially uniform
thickness within a range from about 50 um to about 150 um, for
example about 50 um. The base radius of curvature of the lower
surface of the covering can be within a range from about 7 mm to
about 8 mm. The lower surface may comprise an aspheric surface or a
bicurve surface and combinations thereof. The upper surface of the
covering can comprise a radius of curvature along the inner portion
within about 0.1 mm curvature of the lower surface, such that the
covering is substantially uniform with no substantial refractive
power, for example refractive power within about +/-1D.
[0191] FIGS. 1G1A to 1G1H show a covering as in FIG. 1G1 and
dimensions suitable for use in accordance with embodiments as
described herein such as with experiments, clinical studies and
patient treatment. FIG. 1G1A shows an isometric view of covering
100 having the inner portion 110, the outer portion 120, the taper
120T and rim comprising flange 120F. FIG. 1G1B shows a bottom view
of covering 100. FIG. 1G1C shows a side view of the covering 100.
FIG. 1G1D shows a top view of the covering 100. FIG. 1G1E shows a
side cross sectional view of covering 100 along section D-D. FIG.
1G1F shows detail C of cross-section D-D, including the radius of
curvature R1 of the lower surface of the inner portion 110, and the
upper radius of curvature Rupper of the inner portion 110. The
upper radius of curvature Rupper may correspond substantially to
the lower radius of curvature R1 prior to placement on the eye, for
example to within about +/-1 D of optical power, such that the
inner portion 110 prior to placement may comprise no substantial
optical power. Detail C shows a side cross sectional view of
covering 100 of the inner portion. FIG. 1G1G shows detail B of
cross-section D-D. Detail B shows a side cross sectional view of
the rim comprising flange 120F. The flange 120F has a thickness
109. Flange 120F may comprise a taper extending along a width
102FW, for example from a first thickness 109A of about 35 um to
second thickness 109B of about 25 um extending along width 120FW
near the chamfer. Flange 120F comprises a chamfered edge 120FE to
contact the cornea or conjunctiva along perimeter 120P of the
covering.
[0192] FIG. 1H1 shows spatial frequency and elevation smoothing of
an epithelial irregularity 12I transferred to a front surface 110U
of covering 100 as in FIG. 1-2A. The regenerating epithelium 12R
comprises an irregularity 12I. The covering 100 conforms
substantially to the shape ablated in the stroma when positioned on
the eye as noted above. The covering 100 comprises a rigidity so as
to conform substantially to the ablation profile 20 over about at
least about 3 to 4 mm of the ablated stroma such that the patient
can see and receive optical correction with the ablated surface.
The regenerating epithelium comprises a thickness profile 12RP that
includes irregularity 12I. The conformable covering comprises a
thickness profile of thickness 106 that encompasses a deformation
thickness over the irregularity 106D. The thickness of the covering
can vary over the epithelium to smooth the irregularity transmitted
to the front surface of the covering so as to improve patient
vision consistent with the ablation profile 20 when the covering
conforms to the ablation profile 20. For example thickness 106D
over the irregularity can be less than thickness 106 away from the
irregularity. The irregularity may comprise an indentation and the
covering may be thinner over the indentation. The silicone
elastomer and hydrogel materials as described can be at least
somewhat compressible so as to conform at least partially to the
cornea and form an indentation so as to receive a portion of the
cornea comprising one or more of epithelium or ablated stroma and
decrease aberrations.
[0193] Experimental studies of optical coherence tomography
(hereinafter "OCT") images and Pentacam.TM. images and topography
images, noted below, indicate that the thickness of the inner
portion of the covering 100 can vary so as to decrease optical
aberrations along the upper surface when the covering is adhered to
the cornea. This variation in thickness can be related to one or
more of stretching of the covering over the irregularity or
compression of the covering over the irregularity.
[0194] The irregularities of the epithelium generally comprise
spatial frequencies that are greater than the spatial frequencies
of the vision correcting portion of the ablation. The covering can
provide spatial filtering of the frequencies of the underlying
surface so as to inhibit relatively higher spatial frequencies of
epithelial irregularities and pass relatively lower spatial
frequencies corresponding to vision correction, such as lower
spatial frequencies corresponding to sphere and cylinder. The
spatial frequencies ablation profile 20 that are useful to
correction vision can be lower than the spatial frequencies of the
irregularities, and the spatial dimensions of the vision correction
greater than the dimensions of the irregularities. For example, the
spatial frequencies of the vision correction can correspond to
periods of oscillation less than the periods of oscillation of the
irregularities.
[0195] FIG. 1H2 shows spatial frequency and elevation smoothing of
the epithelial irregularity with a plot of relative height relative
for the upper surface of the covering and the upper surface of the
irregularity. The irregularity of the regenerating epithelium 12R
may comprise a profile height 12RPH and profile width 12RPW. The
upper surface of the covering may comprise a profile 110UP. The
irregularity of the upper surface corresponding comprises a width
110UPW and a height 110UPH. Height 110UPH is less than height 12RPH
so as to correspond to smoothing of the irregularity. Width 110UPW
is greater than width 12RPW so as to correspond to smoothing of the
irregularity. Profile 110UP of the upper surface of the covering
corresponds to lower frequencies than profile 12RP, such that the
covering comprise a low pass spatial frequency filter. This can be
seen with the Pentacam.TM. and topography data shown below in
conjunction with OCT images showing that the covering and cornea
conform without a substantially gap disposed therebetween.
Alternatively or in combination, the covering can smooth the cornea
when a gap is present, for example when a portion of the cornea is
smoothed with contact to the covering and the gap provides an
environment for the epithelium to grow smoothly over the
ablation.
[0196] Based on the teachings described herein, a person of
ordinary skill in the art can conduct studies to determine
empirically the rigidity of the inner portion so as to pass
substantially vision correction spatial frequencies of the ablation
to the upper surface of the covering and inhibit spatial
frequencies of the irregularities of the ablated stroma and
epithelium, for example with Pentacam.TM. and topography studies as
described in the experimental section.
[0197] Work in relation to the embodiments as described herein
indicates that a covering comprising a modulus within a range from
about 4 MPa to about 20 MPa can provide smoothing with low pass
spatial frequency filtering as described with reference to FIGS.
1H1 and 1H2. The covering may comprise an elastically stretchable
material, for example an elastomer or a hydrogel, such that the
lens can conform at least partially to the ablated stroma and exert
at least some pressure on the ablated stroma and epithelium when at
least partially conformed so as to smooth irregularities of the
epithelium and irregularities of the stroma. The covering can
comprise a thickness and a hardness so as to provide the spatial
frequency filtering to improve vision in post-PRK patients with the
modulus within the range from about 4 MPa to about 20 MPa. For
example, the lens thickness can be increased to increase the
modulus, decreased to decrease the modulus. The hardness of the
material can be increased to increase the modulus and decreased to
decrease the modulus. The modulus within the range from about 4 MPa
to about 20 MPa can attenuate substantially higher spatial
frequencies corresponding to irregularities of the epithelium and
stroma so as to smooth the high spatial frequencies corresponding
to the irregularities that can degrade vision, and can conform
substantially to lower spatial frequencies that correspond to the
vision correction so as to pass the lower spatial frequencies
corresponding to vision correction so that the patient can
experience an improvement in vision when the epithelium regenerates
under the covering. For example, the high spatial frequencies may
correspond to frequencies greater than about 1/6 (0.17) cycles per
mm, and the low spatial frequencies may correspond to frequencies
less than about 1/6 (0.17) cycles per mm. A person of ordinary
skill in the art can determine the modulus and corresponding
spatial frequencies to attenuate and pass, in accordance with the
teachings as described herein. For example, the modulus of the
covering can be measured with known methods and apparatus to
measure the modulus of a contact lens, and measurements with
Pentacam.TM. images as described herein can be used to determine
the relationship of the modulus of the measured lens coverings to
smooth irregularities, conformation of the lens coverings to the
ablation, and vision.
[0198] FIG. 1I1 shows an inhibition of transfer of a corneal
irregularity to a front surface of a covering, for example one or
more of a stromal irregularity or an epithelial irregularity. The
front surface of the covering comprises an optical surface for
vision without substantially transfer of the irregularity to the
front surface of the covering.
[0199] FIG. 1I2 shows elevation smoothing of the epithelial
irregularity with a plot of height relative to a reference sphere
for the upper surface of the covering and the upper surface of the
irregularity. The plot shows a substantially spherical front
surface of the covering, such that the transfer of the irregularity
to the front surface is inhibited.
[0200] FIG. 1I3 shows a thickness profile of the covering as in
FIG. 112 so as to smooth irregularities transferred to the front
surface of the covering. The thickness profile can vary in response
to the underlying surface, for example with a decrease in thickness
corresponding to an elevation in the surface profile of the
cornea.
[0201] FIG. 1J1 shows covering 100 having a bicurve profile to fit
an ablated cornea. The bicurve profile may comprise an inner
portion having a lower surface comprising a radius of curvature R1
and an outer portion having a radius of curvature R1B. The inner
portion may comprise a radius selected to fit approximately the
post-ablated cornea, for example to within about +/-2D. The outer
portion may comprise the radius of curvature R1B sized to
correspond to the outer unablated cornea, for example to within
about +/-2D. The covering may comprise an elastic material with a
modulus within a range from about 4 MPa to about 20 MPa, such that
the covering can conform at least partially to the cornea and
smooth irregularities of the cornea as described herein. R1 can be
longer than R1B, for example with PRK ablation to treat myopia. R1
can be shorter than R2, for example with PRK ablation to threat
hyperopia.
[0202] FIG. 1J2 shows covering 100 having an oblate profile to fit
an ablated cornea, for example a cornea ablated for myopia. The
covering may comprise an apical radius of curvature corresponding
to R1 near a center of the covering, and a peripheral radius of
curvature, based on the conic constant of the oblate profile of the
lower surface of covering 100. Alternatively, the lower covering
100 may comprise a prolate ellipsoid shape to fit a PRK ablation to
treat hyperopia.
[0203] FIG. 1J3 shows covering 100 having a tricurve profile to fit
sclera and an ablated cornea. The tricurve covering may comprise an
inner portion with an inner lower surface having radius of
curvature R1 and an outer portion comprising an outer lower surface
having radius of curvature R1B, as described above. The covering
may comprise a third portion 130 disposed outside the outer portion
and having a third radius of curvature R1C sized to fit the sclera
and contact the conjunctiva disposed over the sclera. Work in
relation to embodiments suggests that coupling to the sclera may
improve alignment of the lens on the cornea.
[0204] The covering 100 having the tricurve profile may comprise
dimensions sized to fit the cornea and sclera of the eye 2. The
covering 100 having the tricurve profile may comprise an inner
portion 110 and an outer portion 120 as described herein. The outer
portion 120 may comprise the third scleral portion 130S having
curvature R1C shaped to fit the sclera of the eye, for example
shaped so as to contact the conjunctiva of the eye such that the
conjunctiva is located between the sclera and the scleral portion
130S. The inner portion 110 may comprise a dimension 102 and the
outer portion 120 may comprise a dimension 104 as described herein.
The covering 100 may comprise a sag height 105 extending between an
upper location of the inner portion 110 and the outer boundary of
outer portion 120 shaped to fit the cornea. The third portion 130
may comprise a dimension across 103.
[0205] The dimension 102, the dimension 104 and the dimension 103
can be sized to the eye based on measurements of the eye. The
dimension 103 may correspond to an annular region of the sclera
extending from the limbus to the outer boundary of the third
portion across a distance within a range from about 1 to 4 mm, for
example within a range from about 1.5 to 2 mm. The size of the
limbus of the eye can be measured so as to correspond to dimension
104, for example, and can be within a range from about 11 to 13 mm.
The ablation zone can correspond to dimension 102, and dimension
102 corresponding to the rigid inner portion can be sized about 0.5
to about 2 mm less than the dimension across the ablation zone,
such that the soft outer portion 120 contacts the eye near the edge
of the ablation and the epithelial debridement.
[0206] The radius of curvature R1C of portion 130 can be determined
so as to fit the eye, and can be within a range from about 12
mm+/-3 mm. The outer portion can be fit to within about +/-0.5 mm,
for example to within about +/-0.25 mm.
[0207] The dimensions of the covering 100 can be determined in many
ways, for example with topography measurements of the cornea and
sclera. The corneal and scleral topography can be measured with
many instruments, such as with the Orbscan.TM. topography system
commercially available from Bausch and Lomb, and the Pentacam.TM.
Scheimpflug camera system commercially available from Oculus. The
ablation profile can be combined with the topography to determine
the shape of the eye.
[0208] The dimensions of covering 100 can be sized to one or more
of the cornea and sclera based on tolerances that may be determined
clinically.
[0209] The outer portion 120 and the third portion 130 may comprise
openings such as fenestrations as described herein, for example
when the material comprises silicone.
[0210] The outer portion 120 and third portion 130 may comprise a
hydrogel material, for example a silicone hydrogel material, and
the inner portion 110 may comprise the rigid material 110M, for
example second layer 100L2 and second material 110M2 between first
layer 100L1 of first material 110M1 and third layer 100L3 of third
material 110M3 as described herein.
[0211] As the tricurve covering may couple to the sclera so as to
provide environment 100E to promote epithelial regeneration without
substantially sealing the cornea, the outer portion 120 of the
covering and the third portion 130 of the covering may comprise
substantially water permeable material, for example when the inner
portion 110 comprises the rigid material as described herein.
[0212] FIG. 1J4 shows covering 100 having a curved profile to fit
sclera and an oblate profile to fit ablated cornea. The covering
comprises the inner portion having the lower surface with the
oblate profile having radius of curvature R1 comprising an apical
radius of curvature and radius of curvature RO, and an outer
portion comprising a lower surface having radius R1C to couple to
the sclera as described herein. The apical radius of curvature may
comprise a first radius of curvature and the radius of curvature R0
may comprise a second radius of curvature corresponding to a conic
constant of the oblate profile.
[0213] The portions of the coverings as described herein, for
example the inner portion and the outer portion, may comprise a
junction wherein a first portion connects with a second portion,
and the junction may have the modulus as described herein. The
covering may comprise a contact lens having a central lens portion
having a center stiffness of at least about 2 psi*mm2 coupled to an
outer lenticular junction portion having a lenticular junction
stiffness of at least about 5 psi*mm2.
[0214] FIG. 1J5 shows a covering 100 having the tricurve profile to
fit sclera and the ablated cornea similar to FIG. 1J3. The modulus
and thickness of the sclera contacting portion can be configured in
many ways to fit many eyes with comfort and so as to resist
movement of the inner portion 120. The modulus of sclera coupling
portion 130 may be no more than about 5 MPa and the thickness no
more than about 200 um so as to stretch substantially for comfort
and resist movement of the inner portion when placed on the
sclera.
[0215] The dimension 103 of sclera contacting portion 130 may
correspond to an annular region of the sclera extending from the
limbus to the outer boundary of the third portion across a distance
within a range from about 1 to 4 mm, such that the dimension 103
can be from about 12 mm to about 16 mm, for example from about 14
mm to about 16 mm.
[0216] The radius of curvature R1C, thickness and modulus of the
portion 130 can be configured so as to fit the eye to resist
movement of inner portion 120 and with comfort. The radius of
curvature R1C can be sized less than the radius of curvature of the
sclera and conjunctiva. For example, the radius of curvature R1C
can be no more than about 10 mm, for example no more than about 9
mm when the curvature of the scleral portion of the eye is at least
about 12 mm for example. The third relative rigidity may comprise
no more than about 4E-5 Pa*m 3 so as to stretch substantially for
comfort and resist movement of the inner portion when the outer
portion is placed on the sclera.
[0217] The thickness of the third portion having radius of
curvature R1C can vary, for example from a thickness of about 200
um to a tapered edge.
[0218] FIG. 1J6 shows a tapered edge of the covering having a
tricurve profile to fit sclera and an ablated cornea as in FIG.
1J5. The third portion 130 may comprise a flange 120F having a
narrowing taper extending a distance 120FW to a chamfer 120FE. The
chamfer 120FE can be defined along an outer rim where a first
convexly curved lower surface joins a second convexly curved upper
surface. The convex surfaces along the outer rim allow the covering
to slide along the conjunctiva and the narrowing taper permits the
third portion of the covering to stretch substantially and couple
to the sclera and conjunctiva with decreased resistance for
comfort.
[0219] The dimensions of the covering 100 can be determined in many
ways, for example with topography measurements of the cornea and
sclera. The corneal and scleral topography can be measured with
many instruments, such as with the Orbscan.TM. topography system
commercially available from Bausch and Lomb, and the Pentacam.TM.
Scheimpflug camera system commercially available from Oculus. The
ablation profile can be combined with the topography to determine
the shape of the eye.
[0220] FIG. 1K shows covering 100 having inner portion 110 and
outer portion 120, and fenestrations 100F extending through the
thickness of the covering on the outer portion so as to pass a
medicament when the cornea is sealed. The medicament may comprise
an anesthetic, an analgesic, or other medication, for example. The
covering sealed to the cornea can inhibit the egress of the
medicament toward the epithelial defect so that reepithelialization
is not delayed. For example, an anesthetic such as proparacaine,
lidocaine can be used to inhibit pain when the epithelium
regenerates.
[0221] FIG. 1L shows fitting of a covering 100 to a cornea. The
covering may comprise a base curvature, for example first radius of
curvature R1 of inner portion 110 that may correspond to a radius
of curvature when the covering comprises first configuration 100C1
prior to placement on the cornea. The covering may comprise a
second radius of curvature R1B. The ablated cornea may comprise a
second radius of curvature R2. The outer unablated portion of the
curvature may comprise a corneal radius of curvature RC. The second
radius of R2 of the outer portion 120 can be sized to fit the outer
unablated portion of the cornea having radius of curvature RC, for
example to within about +/-1D corresponding to within about +/-0.2
mm for RC of about 8 mm.
[0222] The first radius of curvature R1 can be greater than the
ablated radius curvature R2 such that the curvature of the inner
portion of the covering is less than the curvature of the cornea.
As the curvature is inversely related to the radius of curvature,
the inner portion 110 has a curvature less than the curvature of
the ablation profile 20 of the cornea when the base radius of
curvature R1 of the inner portion is greater than the radius of
curvature R2 of the ablated cornea. The covering having
substantially uniform thickness as described herein with the
curvature less than the ablated cornea can correct visual
aberrations that may be related to epithelial irregularity 12I, for
example so as to correct temporary myopia related to irregularity
12I.
[0223] Work in relation to embodiments indicates that environment
100E to promote epithelial regeneration can be enhanced when the
curvature of the inner portion 110 is less than the curvature of
the ablated cornea corresponding to radius R2. The epithelium 12
may comprise a thickness T extending between an anterior surface of
the epithelium and a posterior surface of the epithelium, and the
thickness T can vary across the surface of the cornea. The base
radius of curvature R1 sized greater than the radius of curvature
R2 of the ablated profile 20 can define environment 100E with a
concave meniscus profile such that pressure near the boundary of
inner portion 110 is decreased to encourage epithelial migration
inward as indicated by arrows 30 and pressure near a center of
inner portion 110 is increased so as to inhibit formation of
irregularity 12I and provide smooth regeneration of the epithelium.
For example, the inner portion of the covering can have a curvature
corresponding to about 1 to about 2.5 D less optical power than the
ablated profile 20. This amount of lesser curvature of the covering
can correct temporary myopia related to epithelial irregularity 12I
and may also smooth the irregularity based on the deflection
pressure as described herein, for example.
[0224] While the outer portion 120 can be fit in many ways, the
outer portion 120 may comprise radius of curvature R1B
corresponding to about 0 to 2D less optical power than the
corresponding optical power of the unablated cornea having
curvature RC. For example, the unablated portion of the cornea may
have an optical power of about 43D, and the outer portion 120 may
have a curvature R1B corresponding to about 41 to 43D, such that
the covering is fit on the cornea with a fit ranging from matched
to loose. Such fitting can be used with tri-curved coverings as
described herein.
[0225] The tri-curve and oblate covering profiles as described
herein can be sized similarly to the bicurve surface so as to
provide inner portion 110 with a decreased curvature and increased
radius of curvature relative to ablation profile 20 so as to
promote epithelial regeneration. For example inner portion 110 may
comprise an increased apical radius of curvature relative to the
radius of curvature of the ablation profile 20 of the cornea.
[0226] The amount of decreased curvature of inner portion 110 can
be characterized in many ways, for example with Diopters of the
cornea and Diopters of the front or back surface of the inner
portion of the covering. In many embodiments the covering may
comprise an inner portion having radius of curvature R1 that can be
about 2D less than the optical power of the ablated cornea. For
example, when the cornea is ablated from about 43D to about 40D,
the base radius of curvature R1 of covering 100 correspond about
38D, two Diopters flatter than the ablated cornea so as to provide
environment 100E.
[0227] The deflectable coverings having the amount of relative
rigidity within the ranges as described herein can be fit to the
ablated cornea in many ways. As the covering deflects, the patient
can be fit with a covering that can be flatter or steeper than the
ablation prior to placement on the eye, and when the covering is
placed on the eye the covering can deflect substantially in
response to the shape of the ablation so that the patient can see
and receive the visual benefit of the ablation profile.
[0228] In many preferred embodiments, the amount of the difference
in curvature between the front surface of the ablation profile and
the covering prior to placement on the eye can be within a range
from about 0D to about 3D so as to promote vision and epithelial
regeneration. For example, the covering prior to placement with
configuration 100C1 can be flatter than the cornea by an amount
within a range from about 1D to about 3D, and when placed on the
eye the covering deflects so as to conform at least partially to
the ablated cornea. The epithelium may comprise a thickness of
about 50 um. The covering prior to placement with configuration
100C1 having a curvature flatter than the cornea can decrease
pressure to the epithelium near the edge of the covering as the
covering with the flatter curvature may be deflected less when the
inner portion conforms to the ablation. The covering prior to
placement with configuration 100C1 having a curvature flatter than
the cornea can increase pressure to the epithelium along the inner
portion of the ablation as the covering may be deflected less when
the inner portion conforms to the ablation.
[0229] In many embodiments the inner portion 110 has a
substantially uniform thickness and no substantial optical power
such that the optical power of the covering corresponding to the
index of refraction of the covering, the upper surface of the
covering, and the lower surface of the covering, comprises no more
than about +/-1.5D, for example no more than +/-1D. When the
covering having the substantially uniform thickness is placed on
the eye and deflected so as to conform at least partially to the
ablation and smooth the inner 2-3 mm of the cornea, the covering
corresponds substantially to the ablation profile such that the
patient can see.
[0230] FIG. 1M shows deflection of a portion of a covering in
response to an epithelial irregularity so as to smooth the
irregularity. The regenerating epithelium comprises a smoothed
regeneration profile 12RPS and a smoothed irregularity 12S. For
reference, the regeneration profile 12RP without the covering and
irregularity 12I without the covering are shown. The covering can
smooth the epithelium with pressure corresponding to deflection of
the covering as described when the covering 100 comprises a second
configuration 100C2 as described herein.
[0231] FIG. 1N shows a test apparatus 190 to measure deflection of
a portion of a lens in response to a load. The test apparatus 190
may comprise a rigid support having an aperture 192, such that
deflection of the covering 100 through the aperture 192 can be
measured. The aperture 192 has a dimension across 194 that can be
sized smaller than the dimension across inner portion 110, so as to
measure a deflection 110D of the inner portion 110 in response to a
load 196. The deflection 110D may comprise a peak deflection, for
example a distance. The load 196 may comprise a point load or a
load distributed over an area corresponding to diameter 104, for
example a pressure from a gas or liquid on the lower side of the
covering. The covering may comprise a first configuration 100C1
corresponding to the shape of the covering prior to placement on
the eye, and the covering may comprise a second configuration 100C2
when placed on the eye, and the amounts of force and/or pressure to
deflect covering 100 can be determined such that covering 100 can
be deflected without substantially degrading vision and so as to
smooth the epithelium. For example, the covering may deflect
slightly so as to decrease vision no more than about 1 or 2 lines
of visual acuity and such that the covering can smooth the
epithelium and provide environment 100E as described herein.
[0232] The modulus and thickness of the covering can be used to
determine an amount of relative rigidity of the covering 100, the
corresponding amount of force to deflect the covering 100 across a
distance, and the corresponding amount of pressure to smooth the
epithelium with the deflected covering as described herein.
[0233] The amount of relative rigidity can be determined based on
the modulus multiplied with cube of the thickness. The amount of
deflection corresponds to the 6.sup.th power of the deflected span
across the covering, the modulus, and the cube of the thickness.
The approximately fourth order relationship of the span to the
deflection can allow the coverings as described herein to conform
at least partially to the ablation profile within a range from
about 4 to 6 mm, and inhibit substantially irregularities having
diameters of about 3 mm or less, for example.
[0234] The deflection can be approximated with the following
equation:
Deflection.apprxeq.(constant)*(Load*Span 4)/(Modulus*thickness
3)
[0235] The above approximation can be useful to understand the
properties of covering 100, for example with a substantially
uniform thickness of the inner portion. The substantially uniform
thickness may comprise a thickness that is uniform to within about
+/-25%, for example to within about +/-10%, such that the covering
can conform substantially to at least a majority of the surface
area of an ablation zone and inhibit irregularities over a smaller
portion of the ablation zone corresponding to no more than a
minority of the surface area of the ablation. In many embodiments,
the covering conforms over an area having diameter of at least
about 4 mm and inhibits irregularities over an area having a
diameter of no more than about 4 mm, for example less inhibits
irregularities over an area of no more than about 3 mm. For
example, based on the above equations, the deflection is related to
the fourth power of the span, such that for a comparable load, a 2
mm span will have about 1/16.sup.th the deflection of a 4 mm span.
Similarly, a 3 mm span will have a deflection that is about
1/16.sup.th the deflection of a 6 mm span. As the deflection is
related to the cube of the thickness, doubling the thickness can
decrease the deflection by about a factor of 8. The above
approximations can be combined with clinical testing to determine
thicknesses and moduli suitable for incorporation in accordance
with embodiments as described herein.
[0236] The equations for deflection of an unsupported circular span
of a material having a substantially uniform thickness are:
E c = E 1 ( t 1 t 1 + t 2 ) + E 2 ( t 2 t 1 + t 2 ) ##EQU00001##
Relative '' `` Rigidity = E c ( t 1 + t 2 ) 3 ##EQU00001.2## y = 3
wR 4 16 Et 3 ( 5 + v ) ( 1 - v ) ##EQU00001.3## w = y 16 Et 3 ( 5 +
v ) ( 1 - v ) 3 R 4 ##EQU00001.4##
where: W=evenly distributed load over the surface, Pressure (Pa)
R=span of unsupported material (m)
E=Young's Modulus (Pa)
[0237] t=Thickness (m) v=Poisson's Ratio (unit-less, assumed to be
constant among materials) y=Deflection (m)
[0238] Equations for deflection is described in Theory and Analysis
of Elastic Plates, Junuthula Narasimha Reddy, p. 201 equation
5.3.43(1999).
[0239] Although the above equations describe relative rigidity for
a substantially flat surface, the equations can approximate a
curved surface and a person of ordinary skill in the art can
determine the deflection load and relative rigidity empirically
based on the teachings described herein, for example with finite
element modeling.
TABLE-US-00001 TABLE A1 Material, modulus, thickness, relative
rigidity Dk/and deflection load of inner portions of coverings as
described herein. Uniform Button Button Flexural Flexural Relative
Button Thickness Thickness Modulus Modulus Rigidity Material
Material (um) (m) (MPa) (Pa) (Pa*m{circumflex over ( )}3) Dk Dk/t
Rigid 250 2.50.E-04 35 35000000 5.47E-04 600 240 Silicone Rigid 200
2.00.E-04 35 35000000 2.80E-04 600 300 Silicone Rigid 150 1.50.E-04
35 35000000 1.18E-04 600 400 Silicone Rigid 100 1.00.E-04 35
35000000 3.50E-05 600 600 Silicone Rigid 50 5.00.E-05 35 35000000
4.38E-06 600 1200 Silicone Exemplary 293 2.93.E-04 20 20000000
5.03E-04 600 205 Silicone Exemplary 272 2.72.E-04 20 20000000
4.02E-04 600 221 Silicone Exemplary 250 2.50.E-04 20 20000000
3.13E-04 600 240 Silicone Exemplary 215 2.15.E-04 20 20000000
1.99E-04 600 279 Silicone Exemplary 200 2.00.E-04 20 20000000
1.60E-04 600 300 Silicone Exemplary 175 1.75.E-04 20 20000000
1.07E-04 600 343 Silicone Exemplary 150 1.50.E-04 20 20000000
6.75E-05 600 400 Silicone Exemplary 100 1.00.E-04 20 20000000
2.00E-05 600 600 Silicone Exemplary 50 5.00.E-05 20 20000000
2.50E-06 600 1200 Material enflufocon A 25 2.50.E-05 1900
1900000000 2.97E-05 18 72 (Boston ES) enflufocon A 50 5.00.E-05
1900 1900000000 2.38E-04 18 36 enflufocon A 150 1.50.E-04 1900
1900000000 6.41E-03 18 12 hexafocon B 25 2.50.E-05 1160 1160000000
1.81E-05 141 564 (Boston XO2) hexafocon B 50 5.00.E-05 1160
1160000000 1.45E-04 141 282 hexafocon B 150 1.50.E-04 1160
1160000000 3.92E-03 141 94
[0240] As shown in Table A1, an RGP material such as an enflufocon
or hexafocon having a thickness of about 50 um can have a relative
rigidity suitable for epithelial smoothing and so as to conform at
least partially to the ablated stroma. The rigid silicone having a
modulus of about 20 MPa and a thickness of about 250 um will
provide a relative rigidity 3E-4 and deflection under load similar
to the RGP material having a thickness of about 50 um and modulus
of about 1900 MPa so as to provide a relative rigidity of about
2.4E-4. Commercially available RGP lens materials as shown in Table
A1 can be combined in accordance with embodiments as described
herein so as to provide covering 100. Based on the teachings
described herein, a person of ordinary skill in the art can
determine the thickness of the covering based on the modulus and
the intended relative rigidity.
[0241] Work in relation to embodiments in accordance with clinical
studies as described herein has shown that the inner portion 110 of
the covering 100 having the relative rigidity of about 3E-4
(3.times.10.sup.-4 Pa*m 3) can be effective so to improve vision
and conform at least partially of the eye so as to provide at least
some comfort and improve fitting. Many eyes have been measured with
many coverings and work in relation to embodiments indicates that
an inner portion 110 having a relative rigidity within a range from
about 1E-4 to about 5E-4 (Pa*m 3) can allow the covering to conform
to the ablation and smooth the epithelium as described herein. For
example, inner portion 110 may have a relative rigidity within a
range from about 2E-4 to about 4E-4, and the eye can be fit
accordingly based on the deflection of the covering 100.
[0242] The relative rigidity can be related to the amount of
deflection of the covering 100 on the eye. Work in relation to
embodiments indicates that a relative rigidity of inner portion 110
about 3E-4 can deflect about +/-2D when placed on the eye so as to
conform to an ablation to within about +/-2D across the
approximately 5 or 6 mm ablation diameter when an inner diameter of
about 2 or 3 mm is smoothed. A covering 100 having a relative
rigidity of about 1.5 E-4 can deflect about +/-4D when placed on
the eye so as to conform to an ablation to within about +/-4D
across an approximately 5 or 6 mm diameter when an inner diameter
of about 2 or 3 mm is smoothed.
[0243] The outer portion of the covering may comprise a relatively
rigidity less than the inner portion to fit an outer portion of the
eye such as an outer portion of the cornea or to fit the sclera
when placed on the conjunctiva.
[0244] The coverings as described herein may comprise a relative
rigidity corresponding to a range within two or more values of many
of the coverings of Table A1, for example a relative rigidity
within a range from about 2.50E-06 to about 6.41E-03(Pa*m 3), and
two or more intermediate values for example within a range from
about 6.75E-05 to about 5.47E-04(Pa*m 3). Based on the teachings
described herein the covering can have a relative rigidity within
one or more of many ranges such as within a range from about 0.5
E-3 to about 10 E-3 (Pa*m 3), for example a range from about 1 E-3
to about 6 E-3, for example. Based on the teachings described
herein, a person of ordinary skill in the art can conduct clinical
studies to determine empirically the thickness and modulus
corresponding to a relative rigidity of the inner portion 110 for
the covering 100 so as to smooth irregularities and conform
substantially to the ablation zone.
TABLE-US-00002 TABLE A2 Pressure for 5 um deflection at diameters
of 3, 4, 5 and 6 mm for coverings of Table A1. Pressure Required to
obtain 5 um Button Relative deflection (Pa) Button Thickness
Rigidity 3 mm 4 mm 5 mm 6 mm Material (um) (Pa*m{circumflex over (
)}3) span span span span Rigid 250 5.47E-04 1002.2 317.1 129.9 62.6
Silicone Rigid 200 2.80E-04 513.1 162.4 66.5 32.1 Silicone Rigid
150 1.18E-04 216.5 68.5 28.1 13.5 Silicone Rigid 100 3.50E-05 64.1
20.3 8.3 4.0 Silicone Rigid 50 4.38E-06 8.0 2.5 1.0 0.5 Silicone
Exemplary 293 5.03E-04 921.9 291.7 119.5 57.6 Silicone Exemplary
272 4.02E-04 737.6 233.4 95.6 46.1 Silicone Exemplary 250 3.13E-04
572.7 181.2 74.2 35.8 Silicone Exemplary 215 1.99E-04 364.3 115.3
47.2 22.8 Silicone Exemplary 200 1.60E-04 293.2 92.8 38.0 18.3
Silicone Exemplary 175 1.07E-04 196.4 62.2 25.5 12.3 Silicone
Exemplary 150 6.75E-05 123.7 39.1 16.0 7.7 Silicone Exemplary 100
2.00E-05 36.7 11.6 4.8 2.3 Silicone Exemplary 50 2.50E-06 4.6 1.4
0.6 0.3 Silicone enflufocon A 25 2.97E-05 54.4 17.2 7.1 3.4 (Boston
ES) enflufocon A 50 2.38E-04 435.2 137.7 56.4 27.2 enflufocon A 150
6.41E-03 11751.3 3718.2 1523.0 734.5 hexafocon B 25 1.81E-05 33.2
10.5 4.3 2.1 (Boston XO2) hexafocon B 50 1.45E-04 265.7 84.1 34.4
16.6 hexafocon B 150 3.92E-03 7174.5 2270.1 929.8 448.4
[0245] The data of Table A1 and A2 show that the pressure to
deflect a 3 mm zone a distance of 5 um can be about three times the
pressure to deflect a 4 mm zone the distance of 5 um, and about 15
times the pressure to deflect the 6 mm zone the 5 um distance. For
example, for the relative rigidity of about 3.13E-4 (Pa*m 3), the 5
um deflection pressures are 572.7, 181.2, 74.2, 35.8 (Pa) for
diameters of 3, 4, 5 and 6 mm, respectively, such that the central
3 mm of inner portion 110 can provide a compressive force to
irregularities of about 570 Pa when the inner portion 110 conforms
to the ablation across a 6 mm span with a pressure of about 35 Pa,
for example.
[0246] The relative rigidity and deflection pressures can be
determined for many coverings based on the teachings described
herein, for example for coverings having a plurality of layers
having a plurality of materials.
TABLE-US-00003 TABLE A3 Relative Rigidity of Layered Coverings
Material 2 (Soft) Composite Material 1 (Rigid) Flexural Composite
Relative Total Layered Thickness Modulus Thickness Modulus
Thickness Modulus Rigidity Thickness Material (m) (Pa) (m) (Pa) (m)
(Pa) (Pa*m{circumflex over ( )}3) 270 Exemplary 2.40E-04 2.00E+07
3.00E-05 2.00E+06 2.70E-04 1.80E+07 3.54E-04 um Silicone thick
Shield Soft and 1.35E-04 2.00E+07 1.25E-04 2.00E+06 2.70E-04
1.13E+07 1.99E-04 Hard are Equal 150 Exemplary 1.20E-04 2.00E+07
3.00E-05 2.00E+06 1.50E-04 1.64E+07 5.54E-05 um Silicone thick
Shield Soft and 7.50E-05 2.00E+07 7.50E-05 2.00E+06 1.50E-04
1.10E+07 3.71E-05 Hard w/ Equal thickness
[0247] When two or more materials are combined so as to provide two
or more layers, the relative rigidity of each layer can be combined
so as to determine a total composite rigidity. For example, the
combined rigidity can be determined for a covering having first
layer 100L1 of first material, a second layer 100L2 of second
material 110M2 and third layer 100L3 of third material 100L3, in
which the first and third materials can be the same material.
[0248] A weighted average system can be used to treat the two
layers as one material. The relative amounts of each material and
the moduli of the two materials can be combined to determine a
composite modulus based on the weight average of the thickness of
each layer. For example, with 90 um of 20 Mpa material layer and a
10 um of 5 MPa material layer can be combined so as to determine
the composite modulus as 20 MPa*0.9+5 MPa*0.1=18.5 MPa
[0249] The equations described herein accommodate many layers of
different materials and thicknesses.
[0250] Based on the composite modulus, one can multiply the
composite modulus by the overall thickness cubed, in the present
example 18.5 MPa*100 3. Although these calculations can be based on
approximations, a person of ordinary skill in the art can conduct
simulations, for example finite element modeling simulations, so as
to determine the amount of relative rigidity, pressures and
deflection forces and pressures as described herein.
[0251] The index of refraction of one or more layers of covering
100 may correspond substantially to the index of refraction of the
cornea.
[0252] One or more of the materials 110M1, 110M2 or 110M3 may
comprise an index of refraction within a range from about 1.38 to
about 1.43 so as to match the index of refraction of the cornea to
within about +/-0.05. For example, the materials 110M1 and 110M3
may comprise an optically transparent soft silicone elastomer
having an index of refraction of about 1.41 and the material 110M2
may comprise an optically transparent rigid silicone elastomer
having an index of refraction of about 1.43, for example available
from NuSil. Alternatively, material 110M1 and material 110M3 may
comprise silicone hydrogel and material 110M2 may comprise
silicone, for example.
[0253] While the covering may comprise similar materials such as a
more rigid silicone combined with a softer silicone, the covering
may comprise dissimilar materials. For example, and RGP material
can be combined with a hydrogel, such as the bicurve or tricurve
embodiments as described herein. The covering can extend at least
to the limbus for stability. The RGP material may comprise the
second layer 100l2 of the second material 110M2, for example in
accordance with Table A, and the hydrogel may comprise the first
layer 100l1 of the first material 110M1 and the third layer 100l3
of the third material 110M3. The hydrogel may have an index of
refraction from about 1.38 to about 1.42 so as to match the index
of refraction of the cornea of about 1.377 to within about 0.05 and
may comprise one or more of HEMA, NVP, GMA, MMA, SiH, TRS,
HEMA/NVP, MMA/NVP, HEMA/GMA, or SiH/TRS, commercially available
from Vista Optics, UK, for example. The hydrogel comprising
HEMA/NVP, MMA/NVP, or HEMA/GMA may have water content within a
range from about 40% to about 70% so as to comprise the index of
refraction within the range from about 1.38 to about 1.43. A water
content of about 40% corresponds to an index of refraction of about
1.43 and a water content of about 70% corresponds to an index of
refraction of about 1.38. The hydrogel comprising SiH/TRS may
comprise water content within a range from about 20% to about 70%
so as to comprise the index of refraction within the range from
about 1.38 to about 1.43. With these SiH hydrogels a water content
of about 20% corresponds to an index of refraction of about 1.43
and a water content of about 70% corresponds to an index of
refraction of about 1.38.
Coverings Configured to Pump Tear Liquid
[0254] FIG. 2A1 shows covering 100 configured to pump tear liquid
when positioned on a blinking eye.
[0255] FIG. 2A2 shows the covering of FIG. 2A1 configured to pump
tear liquid under the covering. The covering 100 has inner portion
110 and outer portion 120, and fenestrations 100F extending through
the thickness of the covering on the outer portion so as to tear
liquid TL, which may comprise a medicament. The medicament may
comprise an anesthetic, an analgesic, or other medication, for
example.
[0256] The covering 100 comprises an optical component 100A and a
coupling component 100B. The optical component 100A may comprise an
inner portion 110 of covering 100 and the coupling component 100B
may comprise an outer portion 120 of covering 100. The optical
component 100A comprises rigidity sufficient to resist deformation
such that the optical component 100A can correction vision of the
eye. The optical component 100A may comprise a single layer of
material, or a plurality of layers of materials. The coupling
component 100B may comprise a rigidity less than optical component
100A, such that the coupling component can one or more of deflect
or elastically deform so as to conform to the cornea when covered
with the eyelid. The coupling component 100B may comprise an inner
component 100B1 to couple to the optical component, an outer
portion 100B3 to couple to the sclera, and an intermediate portion
100B2. The intermediate portion 100B2 can extend between the inner
component 100B1 and the outer component 100B3 so as define a
chamber when placed on the eye.
[0257] The optical component 100A and the coupling component 100B
can pump tear liquid under the cornea when the eye closes and
opens, for example when the eye blinks. The outer component 100B3
comprising outer portion 120 may comprise fenestrations 100F. For
example, the intermediate portion 100B2 may comprise fenestrations
100F. The outer portion 120 may comprise outer portion 100B3
comprising a sclera coupling portion 130 to contact the conjunctiva
over the sclera and peripheral portion 120P. The sclera coupling
portion 130 may comprise a thin flange portion extending to the
peripheral portion 120P. The sclera coupling portion may comprise a
thin elastic portion capable of elastic deformation when the eye
blinks to allow the optical component to move downward.
Alternatively or in combination, the outer portion 120 may comprise
a rigidity sufficient to deflect when the eye blinks.
[0258] FIG. 2A3 shows a schematic illustration of the covering of
FIGS. 2A1 and 2A2 pumping tear liquid when the eye closes, in
accordance with embodiments of the present invention;
[0259] When placed on the eye, the covering 100 can define a
chamber with the lower surface of the covering extending along the
cornea, the limbus and conjunctiva over the sclera. When the
eyelids are separated, the covering 100 is held loosely on the eye
with slight pressure from the eyelids extending under the outer
portion of the covering. When the eye blinks, the lids extend over
the outer portion 120 of the covering and inner portion 110 so as
to exert pressure on the covering such that the covering is urged
downward toward the cornea and the volume of the chamber under the
covering is decreased. The downward movement of the optical
component 100A of the inner portion 110 of the covering 100 can
move the covering downward so as to pass pumped tear liquid 100TL
through the fenestrations, and in many embodiments the pumped tear
liquid 100TL can pass under the peripheral portion 120P.
[0260] FIG. 2A4 shows a schematic illustration of the covering of
FIGS. 2A1 and 1A2 pumping tear liquid when the eye opens, in
accordance with embodiments of the present invention.
[0261] When the eyelids open, the pressure on the covering is
decreased, such that the covering can move away from the cornea and
increase the volume of the chamber. The movement of the optical
portion 100A away from the cornea can draw pumped tear liquid 100TL
into the covering through the fenestrations, and contact of the
peripheral portion 120P and sclera coupling portion 130 with the
conjunctiva can inhibit flow of tear liquid under the peripheral
portion 120P. In many embodiments, the peripheral portion 120P and
sclera coupling portion 130 can contact the conjunctiva so as to
form a seal when the eyelids open and the optical portion 100A
moves away from the cornea.
[0262] The fenestrations 100F can be located away from the optical
component, for example about 3.5 to about 4.5 mm from a center of
the optical component to decrease optical artifacts of the
fenestrations 100F. However, the fenestrations may be located
within the optical component when one or more of sufficiently small
or sufficiently few so as to not produce perceptible visual
artifacts. The fenestrations may comprise a patter to indicate the
orientation of the covering 100 on the cornea. For example the
upper fenestration and lower fenestrations may indicated a 90
degree axis on the patient and horizontal fenestrations can be
provided to indicated the location of the 180 degree axis on the
patient. The fenestrations may comprise additional fenestrations to
be located inferiorly to indicate that the covering is not flipped
by 180 degrees on the patient, for example upside down. The
additional inferior fenestrations may also couple to the rivulet
comprising tear liquid that forms near the lower lid, so as to
facilitate pumping of tear liquid. For example, when the eye blinks
the lower lid may extend over the inferior fenestrations and the
upper lid may extend downward to couple to the lower rivulet. When
the eye opens and the eyelids separate the upper eyelid can draw
tear liquid of the rivulet over the upper fenestration and the
lower eyelid can move inferiorly so as to pass the rivulet over the
inferior rivulets.
[0263] The covering 100 may comprise a base radius R1 of curvature
corresponding to a curvature of a central portion of the cornea.
The covering 100 comprises a first configuration 100C1 when placed
on the cornea and the eyelids are spaced apart and a second
configuration 100C2 when placed on the cornea and the blinks such
that the eyelids. The first configuration 100C1 and the second
configuration 100C2 pump tear liquid under the covering 100.
[0264] The covering 100 may comprise a lower surface corresponding
to one or more of many suitable shapes to fit the covering to the
cornea, such as a natural unablated cornea or an ablated cornea
following refractive surgery such as PRK. The lower surface of the
inner portion 110 of the covering 100 may correspond to base radius
of curvature. With post ablation corneas, the covering can resist
deformation and smooth the epithelium over about 3 mm and may
deflect so as to conform substantially to the ablated cornea over a
larger dimension such as 6 mm. The covering may comprise a second
curve in combination with a first curve, such that the lower
surface comprises a bicurve surface. Alternatively, the lower
surface may correspond to an aspheric surface. For example, an
aspheric surface may comprise an oblate shape and conic constant to
fit a post PRK eye. The curved and aspheric surfaces as described
herein can fit non-ablated eyes and the covering can be selected by
based on the curvature of an unablated central region of the
cornea. Also, it may be helpful to identify a covering that fits
the cornea, for example with selection of one covering from a
plurality of sizes.
[0265] The covering 100 may comprise an inner portion 110 having an
optical component 1 100A. The optical component 100A may comprise
an inner portion 110 of the covering 100. The optical component may
have a modulus within a range from about 5 MPa to about 40 MPa, and
a thickness within a range from about 100 um to about 300 um such
that central portion can have sufficient rigidity to resist
deformation and smooth irregularities and correct vision. The
covering may comprise an elastomeric stretchable material such that
the covering can stretch to fit the cornea, for example. The
covering having the modulus within a range from about 4 MPa to
about 40 MPa can be formed in many ways as described herein. For
example, the covering may comprise a single piece of material
having a non-uniform thickness extending across the cornea. The
covering can be shaped in many ways and may comprise a single piece
of one material, or may comprise a single piece composed to two
similar materials, or may comprise a plurality of materials joined
together.
[0266] FIG. 2B1 shows covering 100 having a tricurve profile to fit
sclera and cornea. The tricurve profile can be used to fit an
unablated natural eye, in which the base curvature R1 corresponds
to the optically used central portion of the cornea. For ablated
corneas, the base curvature R1 may correspond to the ablated
cornea. The tricurve covering may comprise an inner portion with an
inner lower surface having radius of curvature R1 and an outer
portion comprising an outer lower surface having radius of
curvature R1B. The outer portion 120 may comprise the sclera
coupling portion 130 having a third radius of curvature R1C sized
to fit the conjunctiva located over the sclera and contact the
conjunctiva so as to inhibit sliding movement of inner portion 110.
Work in relation to embodiments suggests that coupling to the
sclera may improve alignment of the lens on the cornea.
[0267] The covering 100 having the tricurve profile may comprise
dimensions sized to fit the cornea and sclera of the eye 2. The
covering 100 having the at least tricurve profile may comprise an
inner portion 110 and an outer portion 120 as described herein. The
outer portion 120 may comprise the third sclera coupling portion
130 having curvature R1C shaped to fit the sclera of the eye, for
example shaped so as to contact the conjunctiva of the eye such
that the conjunctiva is located between the sclera and the sclera
coupling portion 130. The inner portion 110 may comprise a
dimension 102 and the outer portion 120 may comprise a dimension
104 as described herein. The covering 100 may comprise a sag height
105 extending between an upper location of the inner portion 110
and the outer boundary of outer portion 120 shaped to fit the
cornea. The sclera coupling portion 130 may comprise a dimension
across 103.
[0268] The dimension 102, the dimension 104, the dimension 103, the
dimension 105 and the dimension 105S can be sized to the eye based
on measurements of the eye. The dimension 103 may correspond to an
annular region of the sclera extending from the limbus to the outer
boundary of the sclera coupling portion across a distance within a
range from about 1 to 4 mm, for example within a range from about
1.5 to 2 mm. The size of the limbus of the eye can be measured so
as to correspond to dimension 104, for example, and can be within a
range from about 11 to 13 mm. The dimension 105 may correspond to a
height of the eye from the vertex of the cornea to the limbus, and
the dimension 105S may correspond to the sag height were the outer
location of the covering couples to the conjunctiva covering the
sclera.
[0269] The dimension 102 may correspond to an inner region of the
natural cornea or the dimension across an ablation. Dimension 102
may correspond to the more rigid inner portion 110 can be sized
about 0.5 to about 2 mm less than the dimension across the ablation
zone, such that the soft and less rigid outer portion 120 contacts
the eye near the edge of the ablation and the epithelial
debridement.
[0270] The radius of curvature R1C of portion 130 can be determined
so as to fit the eye, and can be within a range from about 12
mm+/-3 mm. The radius R1B of the outer portion can be fit to within
about +/-0.5 mm, for example to within about +/-0.25 mm.
[0271] The dimensions of the covering 100 can be determined in many
ways, for example with topography measurements of the cornea and
sclera. The corneal and scleral topography can be measured with
many instruments, such as with the Orbscan.TM. topography system
commercially available from Bausch and Lomb, and the Pentacam.TM.
Scheimpflug camera system commercially available from Oculus, and
commercially available optical coherence tomography (OCT). The
ablation profile can be combined with the topography to determine
the shape of the eye.
[0272] The dimensions of covering 100 can be sized to one or more
of the cornea and sclera based on tolerances that may be determined
clinically.
[0273] The outer portion 120 and sclera coupling portion 130 may
comprise a hydrogel material, for example a silicone hydrogel
material, and the inner portion 110 may comprise the rigid material
110M, for example second layer 100L2 and second material 110M2
between first layer 100L1 of first material 110M1 and third layer
100L3 of third material 110M3 as described herein.
[0274] The portions of the coverings as described herein, for
example the inner portion and the outer portion, may comprise a
junction wherein a first portion connects with a second portion,
and the junction may have the modulus as described herein. The
covering may comprise a contact lens having a central lens portion
having a center stiffness of at least about 2 psi*mm2 coupled to an
outer lenticular junction portion having a lenticular junction
stiffness of at least about 5 psi*mm2.
[0275] FIG. 2B2 shows covering 100 having a tricurve profile to fit
sclera with slopes of the curved profiles aligned so as to inhibit
ridges at the boundaries of the curved portions, in accordance with
embodiments of the present invention. The inner portion 110
comprises the optical component 100A and the outer portion 120
comprises the coupling component 100B. The coupling component 100B
may comprise a thin layer of material 120M extending under the
optical component 100A for improved comfort and support of the
optical component. The outer portion 120 comprising coupling
component 100B may comprise fenestrations 100F as described herein.
The inner portion 120 comprises first radius R1 along the lower
surface and a first anterior radius R1A along the upper surface.
The outer portion 120 couples to the inner portion with a second
radius R1B aligned with the first radius R1A at a boundary
corresponding to dimension 102. The outer portion 120 has a second
anterior radius R1BA extending along the anterior surface. The
outer portion 120 comprising second radius R1B along the lower
surface to contact the cornea may couple to sclera coupling portion
130 at a location corresponding to the limbus of the eye, for
example along a boundary corresponding to dimension 104. Work in
relation to embodiments suggests that formation of a ridge near the
boundary of the cornea contacting portion and sclera coupling
portion may decrease epithelial cell migration somewhat more than
would be ideal, and the alignment of the curved profiles to inhibit
ridge formation can provide a smooth transition over the limbus and
may decrease mechanical pressure to the limbus. The sclera
contacting portion 130 comprises an upper surface having an
anterior radius of curvature RICA.
[0276] The inner portion 110 can be curved to fit an ablated eye or
a non-ablated eye. The modulus and thickness of the sclera coupling
portion can be configured in many ways to fit many eyes with
comfort and so as to resist movement of the inner portion 120. The
modulus of sclera coupling portion 130 may be no more than about 5
MPa and the thickness no more than about 200 um, for example no
more than 100 um, so as to stretch substantially for comfort and
resist movement of the inner portion when placed on the sclera.
[0277] The dimension 103 of sclera coupling portion 130 may
correspond to an annular region of the sclera extending from the
limbus to the outer boundary of the sclera coupling portion across
a distance within a range from about 1 to 4 mm, such that the
dimension 103 can be from about 12 mm to about 16 mm, for example
from about 14 mm to about 16 mm.
[0278] The radius of curvature R1C, thickness and modulus of the
portion 130 can be configured so as to fit the eye to resist
movement of inner portion 110 and with comfort. The radius of
curvature R1C can be sized less than the radius of curvature of the
sclera and conjunctiva. For example, the radius of curvature R1C
can be no more than about 10 mm, for example no more than about 9
mm when the curvature of the sclera portion of the eye is at least
about 12 mm for example. The third relative rigidity may comprise
no more than about 4E-5 Pa*m 3 so as to stretch substantially for
comfort and resist movement of the inner portion when the outer
portion is placed on the sclera.
[0279] The thickness of the sclera coupling portion having radius
of curvature R1C can vary, for example from a thickness of about
100 um to a tapered edge.
[0280] FIG. 2B2-1 shows alignment of the slope of the lower surface
of the corneal contacting portion comprising second radius R1B with
the slope of the lower surface of the sclera coupling portion 130
comprising radius R1C, such that pressure to the limbus is
decreased substantially. The second slope corresponding to second
radius R1B is given by a height R1BY and a length R1BX, and the
third slope corresponding to third radius R1C is given by height
R1CY and width R1CX. The second slope is aligned with the third
slope such that no substantial ridge is formed at the location
corresponding to the limbus. For example, the first slope can be
substantially equal to the second slope. The slope of the inner
portion 110 can be aligned with the slope of the second portion 120
at a location corresponding to dimension 102 in a similar
manner.
[0281] FIG. 2B3 shows a tapered edge of the covering of FIG. 2B1
having a tricurve profile to fit sclera and cornea. The sclera
coupling portion 130 may comprise a flange 120F having a narrowing
taper extending a distance 120FW to a chamfer 120FE. The chamfer
120FE can be defined along an outer rim where a first convexly
curved lower surface joins a second convexly curved upper surface.
The convex surfaces along the outer rim allow the covering to slide
along the conjunctiva and the narrowing taper permits the sclera
coupling portion of the covering to stretch substantially and
couple to the sclera and conjunctiva with decreased resistance for
comfort.
[0282] The dimensions of the covering 100 can be determined in many
ways, for example with one or more topography measurements or
tomography measurements of the cornea and sclera. The corneal and
sclera topography can be measured with many instruments, such as
with the Orbscan.TM. topography system commercially available from
Bausch and Lomb, and the Pentacam.TM. Scheimpflug camera system
commercially available from Oculus. The tomography can be measured
with optical coherence tomography (hereinafter "OCT") so as to
determine the sag height of the limbus and conjunctiva, for example
with OCT measurement systems commercially available from
Zeiss/Humphrey. The ablation profile can be combined with the
topography to determine the shape of the eye.
[0283] FIG. 2B4 shows a plan view covering 100 having a multi-curve
profile to fit the cornea, limbus and sclera with slopes of the
curved profiles aligned so as to inhibit ridges at the boundaries
of the curved portions, in accordance with embodiments of the
present invention. The covering 100 comprises fenestrations 100F
and optical component 100A for vision correction and outer coupling
component 100B that may pump tear liquid as described herein.
[0284] FIG. 2B5 shows a side sectional view of the covering of FIG.
2B4 and corresponding curved portions to couple to the cornea,
limbus and sclera, in accordance with embodiments of the present
invention;
[0285] The inner portion 110 comprises optical component 100A which
may comprise material 110M. The outer portion 120 comprises
coupling component 100B which may comprise outer material 120M. The
inner portion 110 is coupled to the outer portion along a boundary
corresponding to dimension 102. The lower surface of inner portion
110 has a shape profile corresponding to a first radius R1. The
outer portion 120 couples to the inner portion with a first outer
radius R1B1 of curvature, such that the slopes are aligned as
described herein at a location corresponding to dimension 102. The
outer portion 120 comprises a second outer radius R1B2 of curvature
coupled to the first outer radius of curvature R1B1. The first
outer radius R1B1 of curvature is coupled to the second outer
radius R1B2 of curvature with the slopes aligned as described
herein at a location corresponding to dimension 104A. The outer
portion 120 comprises a third outer radius R1B3 of curvature
coupled to the second outer radius of curvature R1B2. The second
outer radius R1B2 of curvature is coupled to the third outer radius
R1B3 of curvature with the slopes aligned as described herein at a
location corresponding to dimension 104B.
[0286] The first outer radius of curvature R1B1, the second outer
radius of curvature R1B2, and the third outer radius of curvature
R1B3 may comprise values determined from a patient population. The
first radius of curvature R1 may comprise a value determined based
on the patient population. Alternatively or in combination, the
first radius of curvature R1 may correspond to a post ablation
profile.
[0287] The first outer radius of curvature R1B1, the second outer
radius of curvature R1B2, and the third outer radius of curvature
R1B3 can be combined or replaced with an aspheric surface such as a
conic surface. The conic surface can be determined in accordance
with first outer radius of curvature R1B1, the second outer radius
of curvature R1B2, and the third outer radius of curvature R1B3,
such that the conic surface corresponds to values determined from a
patient population.
[0288] The sclera coupling portion 130 may have a lower surface
comprising a first sclera coupling radius R1C1 of curvature and a
second sclera coupling portion having a second sclera coupling
radius R1C2 of curvature. The first sclera coupling portion
comprising radius R1C1 can be aligned to the third radius R1B3 at a
location corresponding to dimension 104. The second sclera coupling
portion comprising radius R1C2 can be aligned to the first sclera
coupling portion having radius R1C1 at a location corresponding to
dimension 120FW corresponding to an inner boundary of tapering
flange 120F.
[0289] FIG. 2B6 shows a side sectional view of the covering of FIG.
2B4 and corresponding curved portions of the upper surface, in
accordance with embodiments of the present invention. The upper
surface may comprise an inner anterior radius of curvature R1A, a
first outer anterior radius of curvature R1B1A, a second outer
anterior radius of curvature R1B2A. The sclera coupling portion 130
may comprise a first anterior radius R1C1A of curvature and a
second anterior coupling radius R1C2A of curvature.
[0290] FIG. 2B7 shows a tapered edge of the covering of FIG. 2B4,
in accordance with embodiments of the present invention;
[0291] FIG. 3A shows a covering 100 comprising a contact lens
placed on the eye with the eyelids separated, in accordance with
embodiments of the present invention. The covering 100 is placed on
the eye such that the tear liquid TL extends under at least a
portion of the covering between the covering and the cornea so as
to provide a chamber 100C. The covering 100 can be fit so as to
match substantially the curvature of the cornea (hereinafter "on
K") or fit slightly flatter than the cornea so as to provide
chamber 100C. Alternatively or in combination, the flange 120F and
sclera coupling portion 120S of the outer portion 120 may comprise
an angle steeper than the conjunctiva such the covering is urged
away from the cornea near inner portion 110 so as to provide
chamber 100C. The covering 100 comprises a sag height 105S1
corresponding to the elevation distance from the center of the
covering to the outer perimeter 120P of the sclera coupling portion
130. The eye lids can be separated for the patient to see an
object.
[0292] FIG. 3B shows a side sectional view of the covering of FIG.
3A with the eyelids closing.
[0293] FIG. 3C shows a front view the covering of FIG. 3A with the
eyelids closing, in accordance with embodiments. The eyelids can
close with a downward movement 22A of the upper eyelid and an
upward movement 22B of the lower eyelid. The closing of the eyelids
exerts pressure on the covering 100 such that covering 100
comprises second configuration 100C2. The second configuration
100C2 comprises the sag height 105 decreased to second sag height
105 S2 such that the volume of chamber 100C decreases and urges
pumped tear fluid 100TL from under the covering. The pumped tear
liquid 100TL flows radially outward under the outer portion 120P
and through fenestrations 100F such as fenestrations not covered by
the eyelid. The pressure of the eyelid can urge the covering 100
toward cornea 10 so as to decrease the volume of chamber 100C. The
volume of chamber 100C can decrease substantially when the outer
portion 120 comprising flange 120F deflects with elastic
deformation. Alternatively or in combination, the outer portion 120
corresponding to the cornea can deflect so as to decrease the
volume of chamber 100C. In many embodiments, the inner portion 110
comprising optical component 100A may deflect with pressure of the
eyelid so as to decrease the volume of chamber 100C.
[0294] FIG. 3D shows side profile the covering of FIG. 3A with the
eyelids opening, in accordance with embodiments of the present
invention. When the eyelids retract with upward movement 22C of the
upper eyelid and downward movement 22D of the lower eyelid, the
covering 100 can return to the first configuration 100C1 having
first sag height 105S1, such that the volume of the chamber
increases. The outer portion 120 comprising flange 120F and
peripheral portion 120P of the sclera coupling portion 130 may
contact the conjunctiva so as to form a contact seal with the
conjunctiva. The contact seal with the conjunctiva encourages flow
of the tear liquid TL through the fenestrations 100F and into the
chamber 100C, such that pumped tear liquid 100TL can be located
between the cornea and the covering 100.
[0295] The tear rivulet of the lower lid can move upward when the
eyes close so as to provide tear liquid on the surface of the eye,
and at least a portion of the rivulet can couple to the upper lid
when the lids contact each other. When the upper lid moves upward
with movement 22C and the lower lid moves downward with movement
22D, the upper lid provides tear liquid TL near the upper
fenestrations to pass through the upper fenestrations and the lower
lid can provide tear liquid TL near the lower fenestrations to move
through the lower fenestrations.
[0296] Repeated blinking of the eye may occur naturally, so as to
pump tear liquid under the covering and rinse the cornea and
conjunctiva under the covering. This pumping and rinsing provided
by the covering can extend the amount of time the covering can be
worn by a patient such as a patient having a normal unablated eye,
and may encourage epithelial regenerations in post PRK eyes, for
example.
[0297] FIG. 3E shows a covering comprising a contact lens placed on
the eye such that the covering is supported with an inner portion
of the cornea and the conjunctiva with the covering separated from
an outer portion of the cornea so as to define a chamber when the
eyelids are separated, in accordance with embodiments of the
present invention. The covering 100 may contact the cornea at an
inner portion of the cornea, for example at a central location. The
inner portion 110 can be sized to fit the cornea centrally as
described herein, for example with on K fitting. The outer portion
of the covering 120 comprising flange 120F and sclera coupling
portion 130 can be sized to contact the conjunctiva when the inner
portion 110 contacts the sclera centrally, such that chamber 100C
is formed over the outer portion of the cornea with a gap extending
between the outer portion of the cornea and the covering. The outer
portion 120 of the covering extending over the outer portion of the
cornea may have a curvature less than the cornea, such that the
outer portion 120 over the outer portion of the cornea can form
chamber 100C when the inner portion 110 is supported with the
cornea and the outer portion 120 comprising flange 120F is coupled
to the conjunctiva. The fenestrations 100F can be located on the
covering to correspond with a location of chamber 100C and the gap
when the eyelids are open. The outer portion 120 comprises a
resistance to deflection sufficient to form chamber 100C when the
eyelids are open and insufficient to resist deflection when the
eyelids close and move over the outer portion such that the outer
portion moves toward the cornea and decrease the gap distance when
the eyelids at least partially cover the outer portion 120.
[0298] The covering 100 can be fit to the cornea to encourage
formation of the chamber 100C and such that covering 100 comprises
an initial configuration 100C1 with chamber 100C formed beneath.
The cornea may comprise a limbus sag height 105L corresponding to
an elevational distance extending from a vertex of the cornea to
the limbus. The limbus may be located a radial distance 105RL from
a measurement axis of the eye. The eye may comprise a conjunctiva
sag height 105C at a radial distance 105RC from the axis of the
eye. The covering may comprise a limbus sag height 105LC at a
location corresponding to the radial distance 105RL to the limbus.
The covering may comprise a conjunctiva sag height 105CC at a
conjunctiva contacting location corresponding to the radial
distance 105RC of the conjunctiva, for example along flange 120F.
In many embodiments, the sag height 105LC of the covering at the
location corresponding to the limbus is no more than the limbus sag
height 105L, and the sag height 105CC of the covering at the
location corresponding to the conjunctiva is no more than the
conjunctiva sag height 105C, such that pressure to the limbus is
decreased. When the covering is placed on the eye, the conjunctiva
coupling portion 130 comprising flange portion 120F can deflect
such that the sag height of the conjunctiva contacting portion is
decreased from 105CC the sag height of the conjunctiva to the sag
height of the conjunctiva 105C, such that the sag height of the
covering comprises a sag deflected sag height 105S2.
[0299] FIG. 3F shows a side sectional view of the covering of FIG.
2E with the eyelids closing such that covering 100 comprises a
configuration 100C2 with chamber 100C having a decreased volume.
When the eyelids close, the upper and lower lids exert pressure on
the covering such that the covering is urged toward the outer
portion of cornea and the conjunctiva. The outer portion of the
covering over the outer portion of the cornea may not have
sufficient resistance to deflection such that the outer portion of
the covering is deflected downward toward the outer portion of the
cornea. The gap distance extending between the outer portion of the
covering over the outer portion of the cornea is decreased, such
that the volume of chamber 100C decreases and pumped tear liquid
100TL flow from chamber 100C through fenestrations 100F and under
the conjunctiva contacting portion 130 comprising flange portion
120F. The upper eyelid can extend across the pupil so as to cover
inferior and superior fenestrations 100F. The upper eyelid may
contact the lower eyelid so as to draw the tear liquid of the
rivulet superiorly when the eye opens, such that tear liquid of the
rivulet can be drawn into the chamber through the inferior and
superior fenestrations.
[0300] The deflection of the outer portion of the covering over the
outer portion of the cornea can be provided with a covering having
a relative rigidity within a range from about 1.0 E-6 Pa*m 3 to
about 6 E-4 Pa*m 3, for example from about 2.5 E-6 Pa*m 3 to about
5 E-4 Pa*m 3. Table A2 shows values suitable of relative rigidity
and corresponding ranges of outer portion 120 corresponding to the
outer portion of the cornea that can be determined based on the
teachings described herein so as to determine the relative rigidity
of the outer portion of the covering to provide resistance to
deflection and form the chamber with the gap when the eyelid is
away from the portion of the covering and so as to deflect toward
the cornea and decrease the gap and corresponding chamber volume
when the eyelid covers the portion of the covering.
[0301] The deflection of the sclera contacting portion 130 to
couple to the conjunctiva can be provided with the sclera
contacting portion 130 comprising a relative rigidity of no more
than about 2 E-4 Pa*m 3, for example no more than about 1 E-4 Pa*m
3, and in many embodiments no more than about 2 E-5 Pa*m 3. Table
A2 shows values suitable of relative rigidity and corresponding
ranges of sclera coupling portion 130 that can be determined based
on the teachings described herein so as to determine the relative
rigidity of the sclera coupling portion of the covering to provide
resistance to deflection and form the chamber with the gap when the
eyelid is away from the portion of the covering and so as to
deflect toward the cornea and decrease the gap and corresponding
chamber volume when the eyelid covers the outer portion of the
covering over the outer portion of the cornea.
[0302] The deflection of the flange portion 120F to couple to the
conjunctiva can be provided with the flange portion 130 comprising
a relative rigidity of no more than about 1 E-4 Pa*m 3, for example
no more than about 2 E-5 Pa*m 3, and in many embodiments no more
than about 2.5 E-6 Pa*m 3. Table A2 shows values suitable of
relative rigidity and corresponding ranges of outer flange portion
120F that can be determined based on the teachings described herein
so as to determine the relative rigidity of the flange portion 120F
of the covering to provide resistance to deflection and form the
chamber with the gap when the eyelid is away from the portion of
the covering and so as to deflect toward the cornea and decrease
the gap and corresponding chamber volume when the eyelid covers the
outer portion of the covering over the outer portion of the
cornea.
[0303] FIG. 3F1 shows a side sectional view of the covering of FIG.
3F with rotation of the eye when the lids close such that sliding
of the covering along the epithelium is inhibited when tear liquid
is pumped, in accordance with embodiments of the present invention.
The axis of the eye can rotate superiorly such that the covering
slides along the upper lid and the lower lid. The axis of the eye
may comprise one or more known axis of the eye and can be
determined in many ways by a person of ordinary skill in the
art.
[0304] FIG. 3G shows a side view sectional view of the covering of
FIG. 3E with the eyelids opening, in accordance with embodiments of
the present invention. The opening of the eyelids decreases
pressure and allows the outer portion of the covering above the
outer portion of the cornea to move away from the cornea. The tear
liquid TL may pass through fenestrations 100F and into the chamber
100C. The outer portion of the covering comprising portion 130 and
flange 120F can contact the conjunctiva to inhibit tear flow and
may seal the covering.
[0305] FIG. 3H shows a side view sectional view of the covering of
FIG. 3E with the eyelids located at an intermediate location such
that the chamber comprises an intermediate configuration 100C12
volume, in accordance with embodiments. The optical component 100A
comprising inner portion 110 may comprise sufficient rigidity and
resistance to deflection so as to provide vision for the patient
when the covering comprises intermediate portion 100C12 having
outer portion 120 deflected so as to decrease volume of chamber
100C. For example, the patient can close the eyelids to the pupil
margin to deflect the outer portion and the optical component 100A
and inner portion 110 can remain substantially undeflected such
that the patient can have vision of 20/20 or better (metric 6/6 or
better) with a portion of one or more eye lids contacting the inner
portion 110. Opening of the eyelids can increase the chamber volume
and pump tear liquid and closing of the eyelids can decrease
chamber volume and pump tear liquid.
[0306] FIG. 3I shows a side view sectional view of the covering of
FIG. 1C4 placed on the eye with hydrogel contacting the eye. The
covering 100 comprises the layer of hydrogel material 120MHG
extending along the posterior surface of the covering so as to
contact the eye with at least a portion of the hydrogel layer. The
covering 100 can be dimensioned to form chamber 100C defined at
least in part with the layer of hydrogel material. The fenestration
may extend through the hydrogel layer so as to provide pumping as
described herein. Alternatively or in combination, the posterior
end of the fenestration can be covered with the hydrogel material
to couple the cornea to the fenestration with the layer of hydrogel
material. The fenestrations covered with the layer of hydrogel
material 120MHG can be located along the deflectable portion of the
covering so as to encourage movement of water and therapeutic
agents along the hydrogel material, for example when the eye
blinks. The hydrogel layer may comprise a medium to pass liquid and
therapeutic agent from the fenestration to a desired location of
the cornea, for example with wicking of the liquid and therapeutic
agent to a central location of the cornea. The covering comprising
the hydrogel layer extending along the lower surface as described
herein can be fit to an unablated eye to provide refractive
correction or fit to an ablated eye as described herein.
[0307] Clinical testing in accordance with embodiments has shown
that the curved portions of the covering can be fit with on
K-values in accordance with corneal curvatures and sag heights and
limbus sag heights and conjunctiva sag heights of a patient
population.
[0308] Appendix I shown herein below provides dimensions and fit
parameters for covering 100 in accordance with embodiments and
teachings as described herein. The coverings may comprise one or
more of the materials in the A series Tables shown herein, for
example. The dimensions and fit parameters of the coverings can
provide pumping of the tear liquid when placed on the cornea in
accordance with embodiments described herein. The tables of
Appendix I identify the coverings for use with steep K corneas,
medium K corneas and flat K corneas, for example. The K values
listed can be based on population norms, such that the coverings
provide pumping as described herein when placed on the eye. The
coverings can be used with non-ablated eyes or ablated eyes, and
the covering can be identified at least in part based on the first
inner curvature R1.
[0309] Table B1 shows covering 100 having a diameter of
approximately 14 mm across and can be fit on K or flatter, for
example as described herein. The table lists R1 corresponding to
the center ablated portion of the cornea. The inner portion 110
comprising optical component 100A and inner coupling component
100B1 has dimension R1 extends about 5 mm across, and the ablation
zone can be larger, for example about 6 mm. The portion
corresponding to radius R1B1 has dimensions of about 5-7 mm across,
and the curvature can be expressed with keratometry values
(K-values) corresponding to the optical power of the eye in
Diopters (D). The portion corresponding to radius R1B2 has
dimensions of about 7-9 mm across. The portion corresponding to
radius R1B3 has dimensions of about 9-11 mm across. The portion
corresponding to R1C1 can extend from about 11 to 13.5 mm across,
and may comprise curvature having one or more values between
portion R1B3 and portion R1C2, for example a radius of curvature
between about 8 mm and about 12 mm such as about 10 mm. The portion
corresponding to R1C2 can extend from about 13.5 to 14 mm across.
The sag height of the portion R1C2 can be from about 3.1 to about
3.4 mm, for example. The portion corresponding to R1C1 can be fit
to the cornea in many ways as described herein, for example with
the tangent of portion R1C1 aligned with R1B3 on the inner boundary
and R1C2 along an outer boundary so as to inhibit ridge formation
as described herein.
[0310] Table B2 shows covering 100 having a diameter of
approximately 14 mm across and can be fit on K or flatter, for
example as described herein. The table lists R1 corresponding to
the center ablated portion of the cornea. The inner portion 110
comprising optical component 100A and inner coupling component
100B1 has dimension R1 extends about 5 mm across, and the ablation
zone can be larger, for example about 6 mm. The portion
corresponding to radius R1B1 has dimensions of about 5-7 mm across,
and the curvature can be expressed with keratometry values
(K-values) corresponding to the optical power of the eye in
Diopters (D). The portion corresponding to radius R1B2 has
dimensions of about 7-9 mm across. The portion corresponding to
radius R1B3 has dimensions of about 9-11 mm across, and these
values range from about 35.75 to about 40, such that each value is
somewhat flatter at the peripheral portion than corresponding
values of Table B1. For example, Table B1 lists the values for R1B3
as having a range from about 36.75 to about 41D. The portion
corresponding to R1C1 can extend from about 11 to 13.5 mm across.
The portion corresponding to R1C2 can extend from about 13.5 to 14
mm across. The sag height of the portion R1C2 can be from about 3.1
to about 3.4 mm, for example. The portion corresponding to R1C1 can
be fit to the cornea in many ways as described herein, for example
with the tangent of portion R1C1 aligned with R1B3 on the inner
boundary and R1C2 along an outer boundary so as to inhibit ridge
formation as described herein.
[0311] Table B3 shows covering 100 having a diameter of
approximately 16 mm across and can be fit on K or flatter, for
example as described herein. The table lists R1 corresponding to
the center ablated portion of the cornea. The inner portion 110
comprising optical component 100A and inner coupling component
100B1 has dimension R1 extends about 5 mm across, and the ablation
zone can be larger, for example about 6 mm. The portion
corresponding to radius R1B1 has dimensions of about 5-7 mm across,
and the curvature can be expressed with keratometry values
(K-values) corresponding to the optical power of the eye in
Diopters (D). The portion corresponding to radius R1B2 has
dimensions of about 7-9 mm across. The portion corresponding to
radius R1B3 has dimensions of about 9-10.5 mm across, and these
values range from about 36.75 to about 41. The portion
corresponding to R1C can extend from about 13 to about 16 mm
across. The sag height of the portion R1C2 can be less than about
3.6 mm, for example, such that portion R1C2 can be deflected when
placed on the eye. The portion corresponding to R1C1 can be fit to
the cornea in many ways as described herein.
[0312] Table B4 shows covering 100 having curvatures for use with
non-ablated eyes so as to pump tear liquid as described herein, for
example with an extended wear contact lens. Covering 100 has a
diameter of approximately 14 mm across and can be fit on K or
flatter, for example as described herein. The table lists R1
corresponding to the center ablated portion of the cornea. The
inner portion 110 comprising optical component 100A and inner
coupling component 100B1 has dimension R1 extends about 5 mm
across. The curvatures of the inner portion corresponding to R1
have curvature values corresponding to optical powers from about 39
D to about 48D, which can be based on population data for unablated
eyes and combined with the curvatures for portions R1B1 to R1B3 and
R1C1 and R1C2, for example. The portion corresponding to radius
R1B1 has dimensions of about 5-7 mm across, and the curvature can
be expressed with keratometry values (K-values) corresponding to
the optical power of the eye in Diopters (D). The portion
corresponding to radius R1B2 has dimensions of about 7-9 mm across.
The portion corresponding to radius R1B3 has dimensions of about
9-11 mm across. The portion corresponding to R1C1 can extend from
about 11 to about 13.5 mm across. The portion corresponding to R1C2
can extend from about 13.5 to 14 mm across. The sag height of the
portion R1C2 can be from about 3.1 to about 3.4 mm, for example.
The portion corresponding to R1C1 can be fit to the cornea in many
ways as described herein, for example with the tangent of portion
R1C1 aligned with R1B3 on the inner boundary and R1C2 along an
outer boundary so as to inhibit ridge formation as described
herein.
[0313] Although Tables B1-B4 list specific curvature values by way
of example, a person of ordinary skill in the art can determine
many curvature values based on the teachings and embodiments
described herein and one or more of the curvatures can be combined
with an aspheric surface, for example an aspheric surface having a
conic constant.
[0314] Methods and Apparatus to Identify Coverings for Eye
Treatment
[0315] FIG. 4 shows apparatus 200 and a plurality 208 of coverings
to treat an eye. The apparatus 200 comprises a cornea and sclera
eye measurement system 202, a wavefront measurement system, a laser
ablation system 204, a topography measurement system 205, a user
device 206 and the plurality of coverings 208.
[0316] The plurality of coverings 208 may comprise coverings 100 as
described herein or commercially available coverings identified
based on the teachings as described herein. The plurality of
coverings 208 may comprise an inventory of coverings comprising a
first covering, a second covering, a third covering, and up to an
Nth covering.
[0317] The sclera measurement system 202 may comprise a processor
having a computer readable memory and communication circuitry. The
sclera measurement system may measure the conjunctiva over the
sclera, and may measure the cornea when the sclera is measured. The
cornea and sclera measurement system 202 may comprise a system to
measure the cornea and the sclera to determine the shape of the
covering to fit the eye. The cornea and sclera measurement system
202 may comprise components of a fluorescence topography based
system for example components of the system commercially available
from PAR technologies. The system may be modified so as to measure
at least about 14 mm across the conjunctiva, sclera and cornea, for
example.
[0318] The laser ablation system 204 may comprise a processor
having a computer readable memory and communication circuitry, and
may comprise a components of a commercially available excimer laser
ablation system available from such as the Wavelight Allegretto
Wave Eye-Q laser ablation system commercially available from Alcon,
the Technolas laser ablation system commercially from Bausch and
Lomb, the Star laser ablation system commercially available from
Abbott Medical Optics, or the MEL laser ablation system
commercially available from Meditech, for example.
[0319] The corneal topography measurement system 205 may comprise a
processor having a computer readable memory and communication
circuitry. The corneal topography measurement system 205 may
comprise one or more of a Placido ring based system, a Scheimpflug
imaging based system, or a florescence topography based system, for
example. The corneal topography measurement system may comprise a
commercially available Placido Ring based system: such as
Orbscan.TM., Atlas.TM., Keratron.TM., TMS.TM., Magellan.TM.,
iTrace.TM. or a Pentacam.TM., for example. The corneal topography
system may comprise as Scheimpflug system: such as the commercially
available Pentacam.TM. and Galilei.TM.. The commercially available
corneal topography based system may comprise a fluorescence
topography system such as the PAR corneal topography system.
[0320] The user communication device 206 may comprise a processor
having a computer readable memory, communication circuitry and a
display, for example a personal digital assistance such as an
iPhone.TM., an iPad.TM., a Blackberry.TM., a tablet PC. The
plurality of coverings 208 may comprise a first covering 100, a
second covering 100 and an Nth covering 100, for example a 10th
covering 100. The plurality of coverings may comprise an inventory
of coverings having shape profiles, sizes, moduli and rigidity so
as to treat the eye as described herein.
[0321] The eye measurement system may measure the eye from the
cornea to the sclera to identify the covering, for example based on
curvature of the sclera, curvature of the cornea, and curvature of
the ablated portion of the cornea.
[0322] The above systems and components can be interchanged and
combined in many ways.
[0323] For example, the sclera measurement system can be used to
measure the topography of the cornea to fit the covering 100. The
laser ablation system 204 may be combined with one or more
measurement systems. For example, the Orbscan Placido ring based
system may be combined with a Technolas laser ablation system and
the Zyoptix wavefront measurement system, each available from
Bausch and Lomb. The commercially available STAR.TM. excimer laser
ablation system may be combined with a WaveScan.TM. wavefront
measurement system, both available from Abbot Medical Optics. The
commercially available MEL laser ablation system may be combined
with the Atlas Placido topography system, for example commercially
available form Zeiss Meditec. The wavefront system and refraction
measurement system may comprise a combined Hartmann Shack
topography and wavefront system, or a full gradient topography
system, for example as is commercially available from Wavefront
Sciences, Inc.
[0324] FIG. 4A shows data structures 200 and a method 300 of
identifying a covering. The data structures 200 may comprise data
structures of one or more of the system 202, the system 204, the
device 206, for example, and may comprise data structures of a
distributed processor system.
[0325] A step 310 inputs data 210
[0326] A step 320 inputs patient measurement data 220
[0327] A step 321 determines refractive error 222. The refractive
error 222 may comprise one or more of:
[0328] sphere (manifest), cylinder, axis
[0329] aberrations, coma, spherical, Zernicke
[0330] wavefront profile map
[0331] A step 322 measures corneal topography (Kinner pre, Kouter
pre) 224. The corneal topography data 224 may comprise one or more
of:
[0332] curvature (1/R) and optical power (D)
[0333] asphericity
[0334] cylinder
[0335] aberrations
[0336] elevation
[0337] sag height corneal vertex to limbus to sclera
[0338] A step 323 measure limbus measurement data 226. The data 226
may comprise one or more of:
[0339] A diameter or a sag height of the limbus, for example the
sag height and diameter of the limbus
[0340] A step 324 measures scleral measurement data 228. The data
228 may comprise one or more of:
[0341] curvature of sclera, a sag height of the sclera at an axial
location, or an angle of the sclera at the axial location, for
example a sag height where an outer portion of the covering 100
contacts the sclera.
[0342] A step 325 determines age data 229 and ethnicity data 229B,
for example corresponding to eye color and size and pupil size
[0343] A step 330 determines laser ablation data--230. The laser
ablation data 230 may comprise one or more of:
manufacturer 232 determined with a step 331; programmed ablation
(e.g. sphere, cylinder& axis) 234 determined with step 332; and
ablation profile data 236 determined with step 332.
[0344] The ablation profile data may comprise one or more of:
[0345] dimensions of outer Boundary [0346] circular, oval,
elliptical
[0347] maximum depth of ablation
[0348] 3D topography shape of ablation
[0349] a Q value for an optimized aspheric ablation
[0350] a physician nomogram, for example to adjust ablation
depth
[0351] A step 340 determines input covering data--240
[0352] A step 341 identifies available coverings 241
[0353] A step 342 provides a Table of available coverings--242. The
table 242 may comprise one or more of: [0354] (N dimensional
array); [0355] outer portion D/curvature/R (Dimension X); [0356]
inner portion D/curvature/R (Dimension Y); [0357] limbal portion
diameter (Dimension Z); [0358] limbal portion D/cuvature/R
(Dimension M); [0359] scleral portion D/curvature/R (Dimension
N);
[0360] A step 342M determines Manufacturer--242M
[0361] A step 343 determines rigidity--243
[0362] A step 344 determines Portions (inner, outer,
scleral)--244
[0363] A step 345 determines Dimensions of each portion--245
[0364] A step 346 determines Rigidity of each portion--246
[0365] A step 345 determines Thickness of each Portion--247
[0366] A step 346 determines Modulus of each Portion--248
[0367] A step 350 determines Ablated Corneal Profile Data--250. The
data 250 may comprise one or more of:
[0368] e.g. Subtract Ablation Profile Data from Corneal Topography
Data
[0369] e.g. Kinner post=Kinner pre-Sph. Equiv. of ablation
(Sph. Equiv.=Sphere+Cylinder/2)
[0370] A step 360 outputs Ablated Corneal Profile Data--260
[0371] A person of ordinary skill in the art will recognize that
steps 350 and 360 may not be necessary when the cornea comprises an
unablated cornea. Alternatively or in combination, the ablation
profile can be set to zero to determine the covering for a
non-ablated cornea.
[0372] A step 361 determines Inner ablated portion profile data may
comprise one or more of:
[0373] e.g. Kinner post
[0374] e.g. 3D profile of ablated cornea
[0375] A step 362 determines outer unablated portion data
[0376] e.g. K (Sph. Equiv) at 5 mm=Kouter
[0377] A step 364 provides one or more of the Limbus Diameter or
the limbus sag height
[0378] A step 365 provides one or more of the Scleral Curvature or
the scleral sag height at an axial location of the sclera, for
example.
[0379] A step 370 determines fit identification parameters based on
cornea output data 270
[0380] The cornea output data may comprise fit profiles for an
unablated cornea such as a cornea to receive an extended wear
contact lens for refractive correction, or fit profiles for an
ablated cornea such as a cornea receiving a PRK ablation, or
combinations thereof.
[0381] A step 371 Determines Unablated Outer Corneal Portion Fit
Parameter X--272. The parameter 272 may comprise one or more
of:
[0382] e.g. X=(Kouter)-(Outer Fit offset)
[0383] e.g. Outer fit offset within range from 0 to 2
[0384] e.g. X=(Kouter in Diopters)-(Fit offset within range from 0
to 2.0D)
[0385] e.g. X-(Kouter in Diopters)-(1D)
[0386] A step 372. Determine Inner Corneal Fit Parameter Y--274.
The parameter 274 may comprise one or more of:
[0387] e.g. Y=(Kinner)-(Vision/Epi promoting offset)
[0388] e.g. Y=(Kinner)-(Vision/Epi promoting offset within a range
from about -1 to 2.5)
[0389] e.g. Y=(Kinner in Diopters)-(Koffset within range from about
1 to about 2.5)
[0390] A step 373 Determines a Limbal Fit Parameter Z--276, such
as
[0391] e.g. Z=Limbus diameter or sag height or combinations
thereof
[0392] A step 374 Determines Scleral D/curvature/R (Dimension
N)--278, such as
[0393] e.g. M=D/curvature/R of sclera or sag height of the sclera
at an axial location or a combination thereof
[0394] A step 380 identifies a Shield Based on Fit Identification
Parameters--280. The identification of the shield covering can be
based on the fit identification parameters and the array of data
comprising the table of available coverings 242.
[0395] A step 381 Determines shield based on values of Dimensions
(X, Y, . . . N)--282
[0396] A step 382 Looks up shield identifier in table based on
values of each of Dimensions of (X, Y, . . . N)--284, such as
[0397] e.g. look up shield in XY table
[0398] A step 383 Determines when fit is acceptable based on
profile differences--286
[0399] A step 384 Assigns Shield--288
[0400] A step 390 Displays shield identifier to health care
provided--290
[0401] Table I. shows a look up table in accordance with
embodiments. The look up table comprises a unique identifier.
TABLE-US-00004 TABLE I Look Up Table for Shield 100 X X = X = X = X
= Outer power Outer power Outer power Outer power Y 38-40 D 38-40 D
38-40 D 38-40 D Y = A1 B1 C1 D1 Inner Power 36-38 D Y = A2 B2 C2 D2
Inner power 38-40 D Y = A3 B3 C3 D3 Inner Power 40-42 D Y = A4 B4
C4 D4 Inner power 42-44 D
[0402] The method 300 can be performed separately from the
structures 200.
[0403] FIG. 4B shows data structures and the method of identifying
the covering as FIG. 4A, in which the fit parameters comprise a two
fit parameters and the data array comprises a two dimensional look
up table. The K's of FIG. 4B refer to the optical power of the
cornea in Diopters (D).
[0404] It should be appreciated that the specific steps illustrated
in FIGS. 4A and 4B provide a particular method of identifying a
covering, according to embodiments of the present invention. Other
sequences of steps may also be performed according to alternative
embodiments. For example, alternative embodiments of the present
invention may perform the steps outlined above in a different
order. Moreover, the individual steps illustrated in FIGS. 4A and
4B may include multiple sub-steps that may be performed in various
sequences as appropriate to the individual step. Furthermore,
additional steps may be added or removed depending on the
particular applications. One of ordinary skill in the art would
recognize many variations, modifications, and alternatives.
[0405] Tables A to C show tables and data structures suitable for
incorporation with data structures 200 and method 300. The tables
of Appendix I show similar data structures for a plurality of
coverings listed in the tables that can be identified
similarly.
TABLE-US-00005 TABLE A Pre-op Screening Log center Mid SHIELD
Subject ID Sphere Cylinder K (D) K (D) CODE EMT OD -1.25 -0.5 42.9
42.2 DZ EMT OS -1.25 -0.5 42.0 41.7 DZ AEC OD -1.75 -1.50 44.0 43.4
EC AEC OS -1.25 -0.25 43.5 43.0 EC JML OD -2.25 -1 43.4 42.9 DZ JML
OS -2.25 -0.5 43.4 43.1 EA EGT OD -1.50 -0.75 43.7 43.4 EC EGT OS
-2.00 -0.25 44.6 44.0 EC REC OD -2.75 -0.5 44.3 43.8 EA REC OS
-2.50 -0.5 44.2 43.8 EA JGG OD -1.00 -0.75 42.6 42.4 DZ JGG OS
-1.50 -1 42.5 42.3 DZ NGT OD -2.50 -1.25 44.5 43.7 EA NGT OS -3.00
-1.25 44.1 43.5 DY DCG OD -0.75 -0.5 43.8 43.4 EF DCG OS -1.25 0
43.9 43.6 EF JRJ OD -2.50 0 44.1 43.6 EC JRJ OS -2.00 0 43.6 43.1
EC REC OD -2.75 -0.5 44.3 43.8 EA REC OS -2.50 -0.5 44.2 43.8 EA
DLL OD -2.75 -0.5 44.1 43.8 EA DLL OS -2.75 0 45.0 44.5 ED
[0406] Table A shows a screening log having a plurality of patients
and a covering identified for each eye of each patient, in
accordance with embodiments.
[0407] Table A shows: a subject ID; eye (OD or OS): refraction
including sphere, cylinder: pre-op K(D) in spherical equivalents
for the inner portion; Mid K in spherical equivalents in the outer
portion; and the corresponding shield code comprising the unique
identifier corresponding the covering that fits the patient. For
patient EMT OD, the refraction is -1.25 sph, -0.5 cyl, the pre-op
center K is 42.9 D and the mid periphery K is 42.2 D, such that the
identified shield code is DZ. If a patient cannot be fit, a code
"not a candidate" can be assigned and no covering is provided for
the patient.
[0408] Table B comprises an array of data to identify a covering
for the eye from among a plurality of coverings, and the properties
for a plurality of coverings and the corresponding properties of
each covering 100 of the plurality. As used herein, a covering
encompasses a shield, and corresponding unique identifier can also
be referred to herein as a code.
TABLE-US-00006 Mid-Peripheral/ Center/Inner Portion Mid/Outer
Portion Center Fitting Outer Portion SHIELD Curve Curve Range
Fitting Range UNIQUE R1 Center/INNER R1B (-1.00 to -2.00) (0 to
-1.50) ID Center OPTICAL POWER Mid Mid min max min max Code (mm)
(D) (mm) (D) (D) (D) (D) (D) DV 9.0 37.5 8.1 41.5 38.50 39.50 41.50
43.00 DW 9.0 37.5 7.8 43.0 38.50 39.50 43.00 44.50 DX 8.8 38.5 8.1
41.5 39.50 40.50 41.50 43.00 DY 8.8 38.5 7.8 43.0 39.50 40.50 43.00
44.50 DZ 8.5 39.5 8.1 41.5 40.50 41.50 41.50 43.00 EA 8.5 39.5 7.8
43.0 40.50 41.50 43.00 44.50 EB 8.5 39.5 7.6 44.5 40.50 41.50 44.50
46.00 EC 8.3 40.5 7.8 43.0 41.50 42.50 43.00 44.50 ED 8.3 40.5 7.6
44.5 41.50 42.50 44.50 46.00 EF 8.1 41.5 7.8 43.0 42.50 43.50 43.00
44.50 EG 8.1 41.5 7.6 44.5 42.50 43.50 44.50 46.00 EG 8.1 41.5 7.6
44.5 42.50 43.50 44.50 46.00
[0409] As shown in Table B, the plurality of coverings has an inner
radius of curvature R1 corresponding to the inner portion 110, and
an outer radius of curvature R1B corresponding to an outer portion
120 of the covering. The radius of curvature R1 of the inner
portion 110 is listed in mm and also in optical power in Diopters.
The "Center Fitting Range" (-1 to -2) shows that the inner portion
can be fit with a covering having a curvature less than the ablated
cornea, so as to promote epithelial regeneration. The covering can
deflect and conform at least partially to the eye with the amount
relative rigidity as described herein, for example an amount
corresponding to a modulus of about 20 MPa and a thickness of about
200 um. The outer portion 120 can have a fitting range of about
1.5D, for example from about 41.5D to about 43D. The outer portion
120 corresponding to the unablated portion of the cornea can be
flatter than the outer portion of the cornea, for example flatter
within a range from about 0 to 1.5D. The flatter outer portion 120
can be coupled to a scleral portion 130, that can contact the
conjunctiva and couple to the sclera. The scleral portion 130 can
resist movement when the inner portion 110 and outer portion 120
provide the environment 100E to promote smooth regeneration of the
epithelium.
TABLE-US-00007 TABLE C Values to Identify Coverings. Shield
allocation Pre-op Planned Shield Shield Subj Sph Cyli SE CTR/Inner
Outer Inner SHIELD CTR/Inner Outer CTR Outer ID (D) (D) (D) K (D) K
(D) K (D) CODE K (D) K (D) diff (D) diff (D) EMT OD -1.25 -0.5
-1.50 42.9 42.2 41.40 DZ 39.50 41.50 -1.90 -0.70 AGP OS -1.25 -0.25
-1.38 42.0 41.7 40.63 DZ 39.50 41.50 -1.13 -0.20 AML OD -1.75 -1.5
-2.50 44.0 43.4 41.50 EC 40.50 43.00 -1.00 -0.40 AML OS -1.25 -0.25
-1.38 43.5 43.0 42.13 EC 40.50 43.00 -1.63 0.00 AMZ OD -2.25 -1
-2.75 43.4 42.9 40.65 DZ 39.50 41.50 -1.15 -1.40 AMZ OS -2.25 -0.5
-2.50 43.4 43.1 40.90 EA 39.50 43.00 -1.40 -0.10 BPS OD -1.5 -0.75
-1.88 43.7 43.4 41.83 EC 40.50 43.00 -1.33 -0.40 BPS OS -2 -0.25
-2.13 44.6 44.0 42.48 EC 40.50 43.00 -1.98 -1.00 DGU OD -2.75 -0.5
-3.00 44.3 43.8 41.30 EA 39.50 43.00 -1.80 -0.80 DGU OS -2.5 -0.5
-2.75 44.2 43.8 41.45 EA 39.50 43.00 -1.95 -0.80 JGG OD -1 -0.75
-1.38 42.6 42.4 41.23 DZ 39.50 41.50 -1.73 -0.90 JGG OS -1.5 -1
-2.00 42.5 42.3 40.50 DZ 39.50 41.50 -1.00 -0.80 KGC OD -2.5 -1.25
-3.13 44.5 43.7 41.38 EA 39.50 43.00 -1.88 -0.70 KGC OS -3 -1.25
-3.63 44.1 43.5 40.48 DY 38.50 43.00 -1.98 -0.50 RBT OD -0.75 -0.5
-1.00 43.8 43.4 42.80 EF 41.50 43.00 -1.30 -0.40 RBT OS -1.25 0
-1.25 43.9 43.6 42.65 EF 41.50 43.00 -1.15 -0.60 SVD OD -2.5 0
-2.50 44.1 43.6 41.60 EC 40.50 43.00 -1.10 -0.60 SVD OS -2 0 -2.00
43.6 43.1 41.60 EC 40.50 43.00 -1.10 -0.10 -2.75 -0.5 -3.00 44.3
43.8 41.30 EA 39.50 43.00 -1.80 -0.80 -2.5 -0.5 -2.75 44.2 43.8
41.45 EA 39.50 43.00 -1.95 -0.80 -2.75 -0.5 -3.00 44.1 43.8 41.10
EA 39.50 43.00 -1.60 -0.80 -2.75 0 -2.75 45.0 44.5 42.25 ED 40.50
44.50 -1.75 0.00
[0410] Table C shows the covering assigned to each eye of each
patient based on the pre-op refraction, the pre-op K's of the inner
portion and the outer portion, the array of data corresponding to
the fit coverings and the parameters of the coverings, and the
logic steps to assign the covering based on the teachings described
herein. For example, patient EMT is assigned a covering DZ based on
the outer K of 42.2 and the planned inner K of 41.4 so as to
provide a covering flatter than the ablated cornea by about 1.9 D.
The "-" of the -1.9 D indicates that the covering corresponds to an
optical power less than the ablated cornea by 1.9D. The outer
difference of -0.70 D indicates that the outer unablated portion of
the cornea is fit with a covering having a curvature less than the
outer portion of the cornea. As the covering may comprise the
scleral portion 130 having radius of curvature R1C, the movement of
the covering on the eye can be resisted when the scleral portion
contacts the conjunctiva to couple to the sclera.
[0411] While the covering can be identified in many ways, the
covering can be identified based on the covering within a range of
values and a sequence of logic steps, for example.
TABLE-US-00008 TABLE D Inventory of coverings. SHIELD Code Qty Used
DV 18 0 DW 9 0 DX 13 0 DY 16 1 DZ 16 6 EA 10 7 EB 12 0 EC 15 6 ED
17 1 EF 20 0 EG 18 3 EG 14 0
[0412] The inventory of coverings can show a number of coverings
available for each covering and the number of coverings used, such
that the health care provider can determine whether additional
coverings should be ordered, for example.
[0413] The embodiments as described herein can be combined in many
ways. As used herein like alphanumeric characters describe like
structures, elements and methods and are interchangeable among the
figures and supporting text to the full extent described and as
understood by a person of ordinary skill in the art in accordance
with the embodiments described herein.
[0414] While the exemplary embodiments have been described in some
detail, by way of example and for clarity of understanding, those
of skill in the art will recognize that a variety of modifications,
adaptations, and changes may be employed. Hence, the scope of the
present invention should be limited solely by the appended
claims.
APPENDIX I
TABLE-US-00009 [0415] TABLE B1 14 mm R1 R1B1 R1B2 R1B3 R1 C2
multicurve center 5-7 mm 7-9 mm 9-11 mm 13.5-14 mm SAG designs BC
(D) K (D) K (D) K (D) K (D) mm DIA Steep K 36.5 43.50 42.25 39.50
<12 mm BC (140 micron thick) 3.1-3.4 13.8-14.1 mm Medium 36.5
42.00 40.75 38.25 <12 mm BC (140 micron thick) 3.1-3.4 13.8-14.1
mm Flat K 36.5 40.50 39.25 36.75 <12 mm BC (140 micron thick)
3.1-3.4 13.8-14.1 mm Steep K 38.5 44.25 43.00 40.25 <12 mm BC
(140 micron thick) 3.1-3.4 13.8-14.1 mm Medium 38.5 42.75 41.50
39.00 <12 mm BC (140 micron thick) 3.1-3.4 13.8-14.1 mm Flat K
38.5 41.25 40.00 37.50 <12 mm BC (140 micron thick) 3.1-3.4
13.8-14.1 mm Steep K 40.5 45.00 43.75 41.00 <12 mm BC (140
micron thick) 3.1-3.4 13.8-14.1 mm Medium 40.5 43.50 42.25 39.75
<12 mm BC (140 micron thick) 3.1-3.4 13.8-14.1 mm Flat K 40.5
42.00 40.75 38.25 <12 mm BC (140 micron thick) 3.1-3.4 13.8-14.1
mm
TABLE-US-00010 TABLE B2 Flatter periphery design 14 mm R1 R1B1 R1B2
R1B3 R1 C2 multicurve center 5-7 mm 7-9 mm 9-11 mm 13.5-14 mm SAG
designs BC (D) K (D) K (D) K (D) K (D) (mm) DIA Steep K 36.5 43.50
42.25 38.50 <12 mm BC (140 micron thick) 3.1-3.4 13.8-14.1 mm
Medium 36.5 42.00 40.75 37.25 <12 mm BC (140 micron thick)
3.1-3.4 13.8-14.1 mm Flat K 36.5 40.50 39.25 35.75 <12 mm BC
(140 micron thick) 3.1-3.4 13.8-14.1 mm Steep K 38.5 44.25 43.00
39.25 <12 mm BC (140 micron thick) 3.1-3.4 13.8-14.1 mm Medium
38.5 42.75 41.50 38.00 <12 mm BC (140 micron thick) 3.1-3.4
13.8-14.1 mm Flat K 38.5 41.25 40.00 36.50 <12 mm BC (140 micron
thick) 3.1-3.4 13.8-14.1 mm Steep K 40.5 45.00 43.75 40.00 <12
mm BC (140 micron thick) 3.1-3.4 13.8-14.1 mm Medium 40.5 43.50
42.25 38.75 <12 mm BC (140 micron thick) 3.1-3.4 13.8-14.1 mm
Flat K 40.5 42.00 40.75 37.25 <12 mm BC (140 micron thick)
3.1-3.4 13.8-14.1 mm
TABLE-US-00011 TABLE B3 Large shield (16 mm) R1 R1B1 R1B2 R1B3
multicurve center 5-7 mm 7-9 mm 9-10.5 mm 10.5-13 mm SAG designs BC
K (D) K (D) K (D) K (D) 13-16 mm (mm) DIA Steep K 36.5 43.50 42.25
39.50 <10.0 mm/33.75 D <14.5 mm/23 D .ltoreq.3.6 15.6-16.1 mm
Medium 36.5 42.00 40.75 38.25 <10.0 mm/33.75 D <14.5 mm/23 D
.ltoreq.3.6 15.6-16.1 mm Flat K 36.5 40.50 39.25 36.75 <10.0
mm/33.75 D <14.5 mm/23 D .ltoreq.3.6 15.6-16.1 mm Steep K 38.5
44.25 43.00 40.25 <10.0 mm/33.75 D <14.5 mm/23 D .ltoreq.3.6
15.6-16.1 mm Medium 38.5 42.75 41.50 39.00 <10.0 mm/33.75 D
<14.5 mm/23 D .ltoreq.3.6 15.6-16.1 mm Flat K 38.5 41.25 40.00
37.50 <10.0 mm/33.75 D <14.5 mm/23 D .ltoreq.3.6 15.6-16.1 mm
Steep K 40.5 45.00 43.75 41.00 <10.0 mm/33.75 D <14.5 mm/23 D
.ltoreq.3.6 15.6-16.1 mm Medium 40.5 43.50 42.25 39.75 <10.0
mm/33.75 D <14.5 mm/23 D .ltoreq.3.6 15.6-16.1 mm Flat K 40.5
42.00 40.75 38.25 <10.0 mm/33.75 D <14.5 mm/23 D .ltoreq.3.6
15.6-16.1 mm
TABLE-US-00012 TABLE B4 R1 R1B1 R1B2 R1B3 R1C Multicurve center BC
5-7 mm 7-9 mm 9-11 mm 13.5-14 mm SAG CL designs (D) K (D) K (D) K
(D) K (D) (mm) DIA CL central Steep K 40 41.75 39.00 39.00 <12
mm BC (140 micron thick) 3.1-3.4 13.8-14.1 mm curve 1 Medium 40.00
39.75 37.25 37.25 <12 mm BC (140 micron thick) 3.1-3.4 13.8-14.1
mm Flat K 40.00 37.75 35.25 35.25 <12 mm BC (140 micron thick)
3.1-3.4 13.8-14.1 mm CL central Steep K 42.00 43.75 41.00 41.00
<12 mm BC (140 micron thick) 3.1-3.4 13.8-14.1 mm curve 2 Medium
42.00 41.75 39.25 39.25 <12 mm BC (140 micron thick) 3.1-3.4
13.8-14.1 mm Flat K 42.00 39.75 37.25 37.25 <12 mm BC (140
micron thick) 3.1-3.4 13.8-14.1 mm CL central Steep K 44.000 44.75
42.00 42.00 <12 mm BC (140 micron thick) 3.1-3.4 13.8-14.1 mm
curve 3 Medium 44.00 43.25 40.75 40.75 <12 mm BC (140 micron
thick) 3.1-3.4 13.8-14.1 mm Flat K 44.00 41.75 39.25 39.25 <12
mm BC (140 micron thick) 3.1-3.4 13.8-14.1 mm CL central Steep K
46.00 46.75 44.00 44.00 <12 mm BC (140 micron thick) 3.1-3.4
13.8-14.1 mm curve 4 Medium 46.00 45.25 42.75 42.75 <12 mm BC
(140 micron thick) 3.1-3.4 13.8-14.1 mm Flat K 46.00 43.75 41.25
41.25 <12 mm BC (140 micron thick) 3.1-3.4 13.8-14.1 mm
* * * * *