U.S. patent application number 15/652855 was filed with the patent office on 2017-11-02 for eye covering and refractive correction methods and apparatus having improved tear flow, comfort, and/or applicability.
The applicant listed for this patent is NexisVision, Inc.. Invention is credited to YAIR ALSTER, MATT CLARKE, EUGENE DE JUAN, JR., BRIAN LEVY, CARY J. REICH, KUANGMON ASHLEY TUAN.
Application Number | 20170315380 15/652855 |
Document ID | / |
Family ID | 47072730 |
Filed Date | 2017-11-02 |
United States Patent
Application |
20170315380 |
Kind Code |
A1 |
DE JUAN, JR.; EUGENE ; et
al. |
November 2, 2017 |
EYE COVERING AND REFRACTIVE CORRECTION METHODS AND APPARATUS HAVING
IMPROVED TEAR FLOW, COMFORT, AND/OR APPLICABILITY
Abstract
An eye covering such as a contact lens may comprise one or more
structures to pump tear liquid 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
material having fenestrations to draw tear liquid under the
covering and an outer portion shaped to contact the conjunctiva
over the sclera, such that when the eye closes pressure of one or
more eyelids urges tear liquid through one or more fenestrations
and under the outer portion shaped to contact the conjunctiva. When
the eye blinks, the pressure of the one or more eyelids can urge
the covering toward the cornea such that tear liquid can pass
through the fenestrations
Inventors: |
DE JUAN, JR.; EUGENE; (SAN
FRANCISCO, CA) ; REICH; CARY J.; (LOS GATOS, CA)
; ALSTER; YAIR; (PALO ALTO, CA) ; CLARKE;
MATT; (MOUNTAIN VIEW, CA) ; TUAN; KUANGMON
ASHLEY; (MOUNTAIN VIEW, CA) ; LEVY; BRIAN;
(NEW YORK, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NexisVision, Inc. |
Menlo Park |
CA |
US |
|
|
Family ID: |
47072730 |
Appl. No.: |
15/652855 |
Filed: |
July 18, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14468075 |
Aug 25, 2014 |
9740025 |
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15652855 |
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13456168 |
Apr 25, 2012 |
8864306 |
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14468075 |
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61636404 |
Apr 20, 2012 |
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61507971 |
Jul 14, 2011 |
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61480222 |
Apr 28, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02C 7/022 20130101;
G02C 7/049 20130101; G02C 7/047 20130101; G02C 7/04 20130101; G02C
7/024 20130101 |
International
Class: |
G02C 7/04 20060101
G02C007/04; G02C 7/04 20060101 G02C007/04; G02C 7/02 20060101
G02C007/02; G02C 7/04 20060101 G02C007/04; G02C 7/02 20060101
G02C007/02 |
Claims
1. An ophthalmic lens to correct refractive error of an eye,
wherein, the eye comprises a pupil, a cornea, a conjunctiva, and a
viewing axis; and the ophthalmic lens comprises: an inner optic
portion configured to correct refractive error; and a peripheral
portion configured to support the inner optic portion in relation
to the pupil; wherein correcting refractive error is independent of
rotational orientation of the ophthalmic lens about the viewing
axis of the eye.
2. The ophthalmic lens of claim 1, wherein the refractive error
comprises astigmatic error.
3. The ophthalmic lens of claim 1, wherein the astigmatic error is
throughout a range of at least about 0.5 D.
4. The ophthalmic lens of claim 1, wherein the astigmatic error is
throughout a range of at least about 1.5 D.
5. The ophthalmic lens of claim 1, wherein the refractive error
comprises astigmatism, high-order aberration, or a combination
thereof.
6. The ophthalmic lens of claim 1, wherein the refractive error
comprises non-spherical optical aberrations.
7. The ophthalmic lens of claim 1, wherein the non-spherical
optical aberrations comprise astigmatic error, multifocal error,
higher order aberrations, and custom optically corrective functions
such as pinholes.
8. The ophthalmic lens of claim 1, wherein the refractive error
comprises presbyopia.
9. The ophthalmic lens of claim 1, when applied to the eye,
provides one or more lenticular volumes between the posterior
surface of the inner optical portion and the anterior surface of
the eye.
10. The ophthalmic lens of claim 9, wherein the one more lenticular
volumes comprises tear fluid.
11. The ophthalmic lens of claim 1, when applied to the eye,
refraction of the eye is independent of the shape of the posterior
surface of the inner optical portion, the shape of the lenticular
volume, or both the shape of the posterior surface of the inner
optical portion and the shape of the lenticular volume.
12. The ophthalmic lens of claim 1, wherein each of the inner optic
portion and the peripheral portion is deformable upon motion of an
eyelid.
13. The ophthalmic lens of claim 1, wherein each of the inner
optical portion and the peripheral portion have a modulus and a
rigidity configured to provide a lenticular volume between the
optical surface of the eye and the ophthalmic lens.
14. The ophthalmic lens of claim 1, wherein, the inner optical
portion comprises a first material having a first modulus; the
peripheral portion comprises a second material having a second
modulus, and the first modulus is greater than the second
modulus.
15. The ophthalmic lens of claim 1, wherein, the inner optical
portion comprises a first material having a first rigidity; the
peripheral portion comprises a second material having a second
rigidity, and the first rigidity is greater than the second
rigidity.
16. The ophthalmic lens of claim 1, wherein each of the inner
optical portion and the peripheral component comprise a silicone, a
silicone hydrogel, or a combination thereof.
17. A method of treating refractive error of an eye of a patient,
comprising applying the ophthalmic lens of claim 1 to an eye of a
patient in need of such treatment.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 14/468,075 filed on Aug. 25, 2014, now allowed, which is a
divisional of U.S. application Ser. No. 13/456,168, filed on Apr.
25, 2012, issued as U.S. Pat. No. 8,864,306, which claims the
benefit under 35 U.S.C. .sctn.119(e) of U.S. Provisional
Application No. 61/636,404 filed on Apr. 20, 2012, U.S. Provisional
Application No. 61/507,971 filed on Jul. 14, 2011, and U.S.
Provisional Application No. 61/480,222 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. 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 never 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 idea 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. Commercially
available contact lenses having a rigid central RGP 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 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 an improved
coverings that provide improved vision for extended amounts of time
and can be used treat normal eyes or eyes having an epithelial
defect, such as an epithelial defect subsequent to refractive
surgery such as PRK. The covering may comprise a contact lens and
can provide improved tear flow such that the covering can be left
on the eye to correct vision for extended amounts of time. The
covering may comprise a water inhibiting layer and one or more
structures to pump tear liquid under the water inhibiting layer of
the covering such that the covering can remain in the eye and
correct vision for an extended amount of time. Alternatively or in
combination, the covering may comprise a hydrogel layer extending
along a posterior surface of the covering coupled to the
fenestrations to provide hydration and patient comfort. The
hydrogel layer may fluidly couple the cornea to the fenestrations
so as to pass tear liquid and therapeutic agents from an anterior
surface of the covering through the fenestrations and hydrogel to
the cornea. In many embodiments, the covering comprises 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. A
hydrogel layer coupled to the fenestrations may extend along a
lower surface of the covering at least a portion of the chamber.
The resistance to deflection of the deflectable outer portion can
be 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 expands. The
fenestrations may extend through the hydrogel layer to provide
pumping. Alternatively or in combination, the hydrogel layer may
cover the posterior end of the fenestrations and the deflection of
the outer portion can encourage movement of liquid and medicament
along the hydrogel. 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.
[0009] In many embodiments, the 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 is 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.
[0010] 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.
[0011] 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.
[0012] In a first aspect, embodiments of the present invention
provide a covering to treat an eye of a patient. The eye has a tear
liquid, a pupil, a cornea, and a conjunctiva. The covering
comprises an optical component to correct vision of the eye and a
coupling component. The optical component comprises a first
rigidity sufficient to resist deformation when placed on the eye.
The coupling component contacts the cornea and the conjunctiva and
supports the optical component in relation to the pupil. The
coupling component comprises an outer portion sized to contact the
conjunctiva, an inner portion to couple to the optical component,
and an intermediate portion extending between the inner portion and
the outer portion. One or more of the optical component or the
coupling component comprises a plurality of fenestrations to pump
the tear liquid when the eye blinks.
[0013] In many embodiments, the covering comprises an inner portion
comprising the optical component and the inner portion of the
coupling component. An outer portion of the covering may comprise
the intermediate portion of the coupling component and the outer
portion of the coupling component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 shows an eye suitable for use with the covering as
described herein, in accordance with embodiments of the present
invention;
[0015] 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:
[0016] FIG. 1A1 shows a covering positioned on an eye and blinking
of the eye, in accordance with embodiments of the present
invention:
[0017] FIG. 1A2 shows the covering of FIG. 1A1 that is capable of
pumping tear liquid under the covering, in accordance with
embodiments of the present invention:
[0018] FIG. 1A3 shows a schematic illustration of the covering of
FIGS. 1A1 and 1A2 pumping tear liquid when the eye closes, in
accordance with embodiments of the present invention;
[0019] FIG. 1A4 shows a schematic illustration of the covering of
FIGS. 1A1 and 1A2 pumping tear liquid when the eye opens, in
accordance with embodiments of the present invention;
[0020] FIG. 1B1 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;
[0021] FIG. 1B2 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;
[0022] FIG. 1B2-1 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;
[0023] FIG. 1B3 shows a tapered edge of the covering of FIG. 1B1,
in accordance with embodiments of the present invention;
[0024] FIG. 1B4 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, in accordance with embodiments of the
present invention;
[0025] FIG. 1B5 shows a side sectional view of the covering of FIG.
1B4 and corresponding curved portions to couple to the cornea,
limbus and sclera, in accordance with embodiments of the present
invention;
[0026] FIG. 1B6 shows a side sectional view of the covering of FIG.
1B4 and corresponding curved portions of the upper surface, in
accordance with embodiments of the present invention;
[0027] FIG. 1B7 shows a tapered edge of the covering of FIG. 1B4,
in accordance with embodiments of the present invention;
[0028] 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;
[0029] 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;
[0030] 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;
[0031] FIG. 1C2A shows a covering as in one or more of FIGS. 1-2A
to 1B7 having a layer of hydrogel material on a posterior surface
of the covering, in accordance with embodiments of the present
invention;
[0032] FIG. 1C2B shows a covering as in one or more of FIGS. 1-2A
to 1B7 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;
[0033] FIG. 1C2C shows a covering as in one or more of FIGS. 1-2A
to 1B7 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;
[0034] 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 on a lower surface, in
accordance with embodiments of the present invention;
[0035] 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 as in FIG. 1B4 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;
[0036] FIG. 105 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;
[0037] FIG. 106 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;
[0038] FIG. 1D shows a covering comprising channels extending
radially outward along a lower surface of the covering, in
accordance with embodiments;
[0039] FIG. 1E shows a covering comprising channels extending
radially inward along a lower surface of the covering, in
accordance with embodiments;
[0040] FIG. 1F shows a test apparatus to measure deflection of a
portion of a lens in response to a load, in accordance with
embodiments;
[0041] FIG. 2A shows a covering comprising a contact lens placed on
the eye with the eyelids separated, in accordance with
embodiments;
[0042] FIG. 2B shows a side sectional view of the covering of FIG.
2A with the eyelids closing, in accordance with embodiments;
[0043] FIG. 2C shows a front view the covering of FIG. 2A with the
eyelids closing, in accordance with embodiments;
[0044] FIG. 2D shows side profile the covering of FIG. 2A with the
eyelids opening, in accordance with embodiments;
[0045] FIG. 2E 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;
[0046] FIG. 2F shows a side sectional view of the covering of FIG.
2E with the eyelids closing, in accordance with embodiments;
[0047] FIG. 2F1 shows a side sectional view of the covering of FIG.
2F 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;
[0048] FIG. 2G shows a side view sectional view of the covering of
FIG. 2E with the eyelids opening, in accordance with
embodiments;
[0049] FIG. 2H shows a side view sectional view of the covering of
FIG. 2E with the eyelids located at an intermediate location such
that the chamber comprises an intermediate volume, in accordance
with embodiments;
[0050] FIG. 2I shows a side view sectional view of the covering of
FIG. 1C4 placed on the eye with hydrogel contacting the eye, in
accordance with embodiments;
[0051] FIG. 3A shows a covering positioned on cornea an eye having
an epithelial defect, in accordance with embodiments;
[0052] FIG. 3B shows a covering in a first configuration prior to
placement on cornea of an eye having an epithelial defect, in
accordance with embodiments;
[0053] FIG. 3C shows the covering of FIG. 3B placed on the eye
having a second configuration, in accordance with embodiments;
[0054] FIG. 4A shows a mold to form an optical component of a
covering;
[0055] FIG. 4B shows a mold to form a covering comprising the
optical component of FIG. 4A;
[0056] FIG. 4C shows a mold to form a covering comprising the
optical component of FIG. 4A and a layer of a soft material of the
covering;
[0057] FIG. 4D shows a mold to form a covering and having a solid
inner component comprising the rigid material placed therein prior
to injection of a flowable material, in accordance with embodiments
of the present invention;
[0058] FIG. 4E shows formation of fenestrations in the covering
with energy, in accordance with embodiments of the present
invention;
[0059] FIG. 4F shows spin coating of a hydrogel material on a
posterior surface of the covering, in accordance with embodiments
of the present invention;
[0060] FIG. 4G shows chemical vapor deposition on the covering
having the hydrogel material formed thereon, in accordance with
embodiments of the present invention; and
[0061] FIG. 4H shows the covering comprising the hydrogel material
packaged in a container, in accordance with embodiments of the
present invention.
[0062] FIG. 5 shows a covering in accordance with certain
embodiments.
[0063] FIG. 6A shows views of radials for an example of a hard lens
positioned on an astigmatic eye.
[0064] FIG. 6B shows views of radials for an example of a soft lens
positioned on an astigmatic eye.
[0065] FIG. 6C shows views of radials for an example of a covering
according to certain embodiments of the present invention
positioned on an astigmatic eye.
DETAILED DESCRIPTION OF THE INVENTION
[0066] 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.
[0067] As used herein, a covering is used to refer to an ophthalmic
device that covers an eye of a patient and that does not by itself
provide refractive vision correction. Ophthalmic devices that
provide refractive correction are referred to herein as contact
lenses or ophthalmic lenses.
[0068] The embodiments described herein can be used to treat eyes
in many ways with a covering such as a contact lens. 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,
and may also be combined with many forms of ocular surgery, such as
photorefractive keratectomy.
[0069] 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, "MPa" as Mega Pascal.
[0070] As used herein, a siloxane bond encompasses a covalent
Si--O--Si bond, for example of a silicone elastomer.
[0071] As used herein, an on K fit of a covering such as a contact
lens encompasses fitting the contact lens to the flattest meridian
of the cornea to and the on K fit can be flatter than the flatters
meridian within about 1.5 D. For example, for a cornea having
keratometer values (hereinafter "K's") of about 44D axis 90 and 43D
axis 180, the on K fit would fit would provide a covering having a
curvature corresponding to an optical power within a range from
about 43D to about 41.5 D for the region of the eye measured. The
on K fit as described herein can allow for tear liquid to form
under the covering such that the tear liquid can be pumped in
accordance with embodiments as described herein.
[0072] The optical power of the cornea in Diopters ("D") can be
related to the radius R of curvature with the formula
D=(1.3375-1)/R, where 1.3375 corresponds to the index of refraction
of the aqueous humor and R corresponds to the radius of curvature
of the cornea. The curvature of the cornea is inversely related to
the radius of curvature R such that as the radius of curvature
increases the curvature of the cornea decreases and such that as
the radius of curvature decreases the curvature of the cornea
increases.
[0073] FIG. 1 shows an eye 2 suitable for use with the covering 100
as described herein. In many embodiments, covering 100 comprises a
contact lens. 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 S of
the eye. The eye 2 has a pars plana PP located near limbus 6. A
conjunctiva C of the eye can be disposed over the sclera. 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
the 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.
[0074] FIG. 1-1A shows an ablated eye immediately following
refractive surgery, for example PRK surgery resulting in an
epithelial defect. The covering comprising the contact lens as
described herein can be placed over the ablated cornea and coupled
to the conjunctiva to provide improved vision. 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 a thickness
12T that can be about 50 .mu.m. A tear liquid covers 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 a cellular
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.
[0075] 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.
[0076] The epithelium may comprise an inner boundary that moves
centripetally inward as indicated by arrows 30.
[0077] 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 irregularities.
[0078] FIG. 1A1 shows covering 100 positioned on a blinking 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 22A and that the lower lid can exert an upper movement 22B
on the eye. The downward movement 22A can be greater than the upper
movement 22B. 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.
[0079] FIG. 1A2 shows the covering of FIG. 1A1 that is capable of
pumping 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.
[0080] 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 100 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.
[0081] 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 100B
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.
[0082] FIG. 1A3 shows a schematic illustration of the covering of
FIGS. 1A1 and 1A2 pumping tear liquid when the eye closes, in
accordance with embodiments of the present invention.
[0083] 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.
[0084] FIG. 1A4 shows a schematic illustration of the covering of
FIGS. 1A1 and 1A2 pumping tear liquid when the eye opens, in
accordance with embodiments of the present invention.
[0085] 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.
[0086] 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 sufficiently small and diameter
and 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.
[0087] 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, collagen.
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 40 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 40 MPa, such that
the covering conforms at least partially to the ablated stroma.
[0088] 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.
[0089] 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 both an upper
surface and a lower surface of the covering. The upper surface may
comprise the wettable coating extending over at least the inner
portion 110.
[0090] The wettable coating 134 may comprise one or more of many
materials. For example, the wettable coating 134 may comprise
polyethylene glycol (PEG), and the PEG coating can be disposed on
Parylene.TM.. Alternatively, the wettable coating 134 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 a hydrocarbon, 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.
[0091] 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.
[0092] 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 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 identity a covering that fits
the cornea, for example with selection of one covering from a
plurality of sizes.
[0093] 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 .mu.m to about 300 .mu.m
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.
[0094] FIG. 1B1 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 130 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.
[0095] 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.
[0096] 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.
[0097] 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.
[0098] 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.
[0099] 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.
[0100] 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.
[0101] 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 110L2 and second material 110M2
between first layer 110L1 of first material 110M1 and third layer
110L3 of third material 110M3 as described herein.
[0102] 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.
[0103] FIG. 1B2 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 R1CA.
[0104] 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 may 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 .mu.m, for example no more
than 100 .mu.m, so as to stretch substantially for comfort and
resist movement of the inner portion when the placed on the
sclera.
[0105] 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.
[0106] 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.
[0107] The thickness of the sclera coupling portion having radius
of curvature R1C can vary, for example from a thickness of about
100 .mu.m to a tapered edge.
[0108] FIG. 1B2-1 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.
[0109] FIG. 1B3 shows a tapered edge of the covering of FIG. 1B1
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.
[0110] 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.
[0111] FIG. 1B4 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.
[0112] FIG. 1B5 shows a side sectional view of the covering of FIG.
1B4 and corresponding curved portions to couple to the cornea,
limbus and sclera, in accordance with embodiments of the present
invention.
[0113] 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.
[0114] 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.
[0115] 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.
[0116] 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.
[0117] FIG. 1B6 shows a side sectional view of the covering of FIG.
1B4 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.
[0118] FIG. 1B7 shows a tapered edge of the covering of FIG. 1B4,
in accordance with embodiments of the present invention.
[0119] FIG. 1C shows therapeutic covering 100 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 cornea. The inner portion 110 comprises
optical component 100A, and the outer portion 120 comprises
coupling component 100B. The inner portion 110 may comprise a
thickness of no more than about 300 microns, for example no more
than about 200 microns. 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.
[0120] 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 portion 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.
[0121] FIG. 1C2 shows covering 100 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 inner portion 110 comprises the optical
component 100A and the outer portion 120 comprises the coupling
component 100B. 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 110L1 of
a first material 110M1, a second layer 110L2 of a second material
110M2 and a third layer 110L3 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
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.
[0122] The soft material comprising soft outer portion 120 composed
of soft material 120M, first layer 110L1 composed of soft material
110M1 and third layer 110L3 composed of soft material 120M3 can
provide improved comfort and healing for the patient, and can
extend the amount of time the covering can be worn in the eye when
combined with the fenestrations 100F and sclera coupling component
130 and peripheral portion 120P and flange 120F as described
herein. 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 one or more of the entrance pupil of the eye or
ablation zone. With ablated eyes, the dimension 102 can be sized
slightly smaller than the ablation dimensions, such as ablation
diameter 20D, so that the epithelium can grow inward and contact
the layer 110L1 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 110M3 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 110L2 of rigid second material 110M2.
[0123] The soft material comprising soft outer portion 120 composed
of soft material 120M, first layer 110L1 composed of soft material
110M1 and third layer 110L3 composed of soft material 120M3 can
have a modulus within a range from about 1 to 20 MPa, for example
within a range from about 1 to 5 MPa.
[0124] The material inner material 120M and 120M2 of second layer
120L2 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 110L2 of
material 120M2 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.
[0125] The layers of covering 100 can comprise dimensions so as to
provide therapeutic benefit when placed on eye 2. The thickness of
layer 110L1 can be from about 5 .mu.m to about 50 .mu.m, for
example, within a range from about 10-30 .mu.m, such that the layer
110L1 can provide a soft at least partially conformable material to
receive the lens. The middle layer 110L2 can be from about 20 .mu.m
to about 150 .mu.m, for example, and material M2 can have a modulus
greater than first material 110M1 of first layer 110L1, so as to
deflect the epithelium of the eye when the middle layer is
deflected. The third layer 110L3 can be within a range from about 5
.mu.m to 50 .mu.m, for example within a range from about 10 .mu.m
to about 30 .mu.m, and can cover second layer 110L2 so as to retain
the second layer in the inner portion 110 of the covering 100.
[0126] The therapeutic covering 100 may comprise a first inner
material 110M and a second outer material 120M, in which the outer
portion 120 comprises a hardness configured to stretch elastically
and conform with one or more of epithelium of the cornea or the
conjunctiva, and in which the inner portion 110 comprises second
hardness configured to smooth the cornea to provide optical
benefit. 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.
[0127] 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.
[0128] FIG. 1C2A shows a covering as in one or more of FIGS. 1-2A
to 1B7 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.
[0129] 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.
[0130] 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 .mu.m
to about 100 .mu.m, for example from about 2 .mu.m to about 50
.mu.m and in many embodiments within a range from about 5 .mu.m to
about 20 .mu.m. 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.
[0131] FIG. 1C2B shows a covering as in one or more of FIGS. 1-2A
to 1B7 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.
[0132] FIG. 1C2C shows a covering 100 as in one or more of FIGS.
1-2A to 1B7 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.
[0133] 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 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.
[0134] 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 as in FIG. 1B4 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.
[0135] 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.
[0136] 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.
[0137] FIG. 1D shows a covering comprising channels 100FC extending
radially outward from fenestrations 100F along a lower surface of
the covering, in accordance with embodiments.
[0138] FIG. 1E shows a covering comprising 100FC channels extending
radially inward from fenestrations 100F along a lower surface of
the covering, in accordance with embodiments.
[0139] FIG. 1F shows a test apparatus 190 to measure deflection of
a portion of a lens in response to a load. The load deflection of
the coverings and composite layers as described herein can be used
to determine the deflection of the covering and corresponding
pumping. Work in relation to embodiments suggests that one or more
of the inner covering or the outer covering contacting the
epithelium may comprise a rigidity such that blinking of the eye
deflects the covering sufficiently with elastic deformation so as
to urge tear liquid from beneath the covering as described herein.
For example, the inner portion 120 of the coverings suited to cover
the ablated cornea and provide pumping as described herein are also
well suited to cover natural unablated corneas to provide vision
correction with pumping of the tear liquid. The outer portion 120
may comprise a rigidity as described herein sufficient to deflect
when the eye blinks and provide elastic deformation that may pump
tear liquid under the covering such as a contact lens.
[0140] 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 C1 corresponding to the shape of the covering
prior to placement on the eye, and the covering may comprise a
second configuration C2 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.
[0141] 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 pressure to smooth the
epithelium with the deflected covering as described herein.
[0142] 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.
[0143] The deflection can be approximated with the following
equation:
Deflection.apprxeq.(constant)*(Load*Span 4)/(Modulus*thickness
3)
[0144] 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.
[0145] 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##
[0146] where:
[0147] W=evenly distributed load over the surface, Pressure
(Pa)
[0148] R=span of unsupported material (m)
[0149] E=Young's Modulus (Pa)
[0150] t=Thickness (m)
[0151] v=Poisson's Ratio (unit-less, assumed to be constant among
materials)
[0152] y=Deflection (m)
[0153] Equation for deflection is described in Theory and analysis
of elastic plates, Junuthula Narasimha Reddy, p. 201 equation
5.3.43 (1999).
[0154] 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 25 2.50.E-05 1900 1900000000
2.97E-05 18 72 A (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 25 2.50.E-05 1160 1160000000
1.81E-05 141 564 B (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
[0155] As shown in Table A1, an RGP material such as an enflufocon
or hexafocon having a thickness of about 50 .mu.m 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 .mu.m will provide a relative rigidity 3E-4 and deflection
under load similar to the RGP material having a thickness of about
50 .mu.m 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.
[0156] 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 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.
[0157] 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.
[0158] 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.
[0159] 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 .mu.m 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 25
2.97E-05 54.4 17.2 7.1 3.4 A (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 25 1.81E-05 33.2 10.5 4.3 2.1 B (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
[0160] The data of Table A1 and A2 show that the pressure to
deflect a 3 mm zone a distance of 5 .mu.m can be about three times
the pressure to deflect a 4 mm zone the distance of 5 .mu.m, and
about 15 times the pressure to deflect the 6 mm zone the 5 .mu.m
distance. For example, for the relative rigidity of about 3.13E-4
(Pa*m 3), the 5 .mu.m 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. By comparison with
intraocular pressure (TOP) measure in mm of Hg, 12 mm of Hg is
about 1,600 Pa, such that the coverings may conform to the cornea,
for example over a 6 mm region, when the eye blinks. This
conformation of the covering to the cornea when the eye blinks can
provide pumping in accordance with embodiments as described
herein.
[0161] 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 .mu.m Exemplary 2.40E-04
2.00E+07 3.00E-05 2.00E+06 2.70E-04 1.80E+07 3.54E-04 thick
Silicone 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 .mu.m Exemplary
1.20E-04 2.00E+07 3.00E-05 2.00E+06 1.50E-04 1.64E+07 5.54E-05
thick Silicone 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
[0162] 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 110L1 of first material, a second layer 110L2 of second
material M2 and third layer 110L3 of third material 110L3, in which
the first and third materials can be the same material.
[0163] 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 .mu.m of 20 Mpa material layer and
a 10 .mu.m 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
[0164] The equations described herein accommodate many layers of
different materials and thicknesses.
[0165] 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.
[0166] The index of refraction of one or more layers of covering
100 may correspond substantially to the index of refraction of the
cornea.
[0167] 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 M2 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 silicone, for example.
[0168] 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 110L2 of the second material 110M2, for example in
accordance with Table A1, and the hydrogel may comprise the first
layer 110L1 of the first material 110M1 and the third layer 110L3
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.
[0169] FIG. 2A shows a covering 100 comprising a contact lens
placed on the eye with the eyelids separated, in accordance with
embodiments. 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 on K or 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 eyelids can be
separated for the patient to see an object.
[0170] FIG. 2B shows a side sectional view of the covering of FIG.
2A with the eyelids closing.
[0171] FIG. 2C shows a front view the covering of FIG. 2A 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
105S2 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 100 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 100.
[0172] FIG. 2D shows side profile the covering of FIG. 2A with the
eyelids opening, in accordance with embodiments. 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 120F 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.
[0173] 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 provide 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.
[0174] 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.
[0175] FIG. 2E 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. 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 an
insufficient to resist deflection when the eyelids move over the
outer portion such that the outer portion moves toward the cornea
and decrease the gap distance when the eyelids close.
[0176] 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 RL 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.
[0177] FIG. 2F 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.
[0178] 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.
[0179] 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.
[0180] 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.
[0181] FIG. 2F1 shows a side sectional view of the covering of FIG.
2F 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. 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.
[0182] FIG. 2G shows a side view sectional view of the covering of
FIG. 2E with the eyelids opening, in accordance with embodiments.
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.
[0183] FIG. 2H shows a side view sectional view of the covering of
FIG. 2E 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 100B
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.
[0184] FIG. 2I 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.
[0185] 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.
[0186] 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 Series A 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.
[0187] 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.
[0188] 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 41 D. 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.
[0189] 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.
[0190] 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.
[0191] 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.
[0192] FIG. 3A shows a covering 100 positioned on cornea 10 an eye
2 having an epithelial defect 11. The covering may comprise a
curved body, for example a curved contact lens body shaped to fit
the cornea.
[0193] 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.
[0194] 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.
[0195] 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.
[0196] A smooth layer 12S of regenerated epithelium 12R may
substantially cover 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.
[0197] 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.
[0198] The covering 100 may comprise an inner portion 110 and an
outer portion 120. The outer portion 110 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 elastomer or silicone hydrogel. The inner portion
120 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 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 can be 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, for example with
deflection pressure as described herein.
[0199] FIG. 3B shows covering 100 in a first configuration prior to
placement on the cornea of an eye having an epithelial defect, such
as an eye having a PRK ablation. The covering 100 comprises
fenestrations 100F. The fenestrations 100F can be located on the
covering such that the fenestrations are located away from the
epithelial defect to pump tear liquid under the covering as
described herein. The covering 100 may comprise inner portion 110
having a base radius R1 of curvature, and the base radius of
curvature may be slightly longer than the ablated cornea such that
the covering can be flatter than the cornea prior to placement on
the cornea. The outer portion 120 comprising sclera coupling
portion 130 may comprise a portion steeper than the cornea to
reduce pressure to the limbus. For example flange portion 120F can
be steeper than the corresponding portions of conjunctiva and
sclera so as to decrease pressure of the covering on the
limbus.
[0200] The base radius R1 can be sized to the cornea in many ways.
For example, the base radius R1 may have a radius corresponding to
the post ablated eye.
[0201] The covering 100 may comprise a modulus within a range from
about 4 MPa to about 35 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 35 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.
[0202] The covering 100 may comprise one or more outer portions
extending outside the inner portion as described herein.
[0203] FIG. 3C shows the covering of FIG. 3B placed on the eye
having a second configuration 100C2 conforming to ablated stromal
tissue and smoothing the epithelium over the ablated stroma, such
that the covering can pump tear liquid as described herein. 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 configuration 100C2 of the covering 100
when positioned on the cornea.
[0204] 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 12C2. For example, irregularities 121 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 121 of the regenerating
epithelium 12R are thinner than the thickness 12T of the peripheral
epithelium.
[0205] 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 35 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 35 MPa can be formed in many ways as described
herein.
[0206] FIGS. 4A to 4H show a method 400 of manufacturing a covering
100 and apparatus for manufacturing the covering as described
herein.
[0207] FIG. 4A shows a mold 600A to form an optical component 100A
of a covering 100 comprising material 110M as described herein. The
optical component 100A may comprise an optically transparent
material such as a silicone, for example. The optical component may
comprise a modulus and thickness and corresponding rigidity as
described herein, so as to provide vision and smoothing of the
cornea. The mold 600A may comprise an optical correction on one
surface and a base curvature on the opposite surface, for example.
With a step 410, the optical component 100A can be formed in mold
600A.
[0208] FIG. 4B shows a mold 600B to form a covering comprising the
optical component of FIG. 4A and the coupling component 100B. The
optical component 100A can be placed in the mold and the flowable
material 120M of the coupling component injected into the mold so
as to form the covering. The solid inner component comprising a
rigid material placed therein prior to injection of a flowable
material. The mold 600B may comprise inner material 110M positioned
within the mold as a solid piece of material and outer material
120M comprising a flowable material injected into mold 600B and
cured around the preformed piece comprising inner material 120M.
The flowable material can be injected around the inner material
100M in many ways. For example, the inner material 110M may
comprise a second layer 110L2 of rigid material 110M2 of the inner
portion 110 as described herein, and the flowable material can be
injected around the upper and lower surfaces of second material
110M2 so as to form a first layer 110L1 of first material 110M1 and
a third layer 110L3 of the third material 110M3 with the flowable
material such that the first material 110M1, the third material
110M3 and the outer material 120M each comprise substantially the
same soft material when cured. With a step 420, the covering
comprising the optical component 100A and the coupling component
100B can be formed
[0209] FIG. 4C shows a mold 600C to form a covering comprising the
optical component of FIG. 4A and a layer of a soft material of the
covering, such that the optical component can be located between
two layers of the coupling component. The optical component 100M
can be removed from the mold as shown in FIG. 4A and placed in the
mold 600C. The flowable material M3 corresponding to layer 110L3
can be injected into the mold and cured. The partially formed inner
component comprising layer 110L2 and layer 110L3 can be removed
from mold 600C. With a step 430, the portion of the covering
comprising the two layers can be formed.
[0210] FIG. 4D shows a mold 600D to form a covering and having a
solid inner component comprising the rigid material placed for
injection of a flowable material, in accordance with embodiments of
the present invention. The mold 600 may comprise inner material
110M positioned within the mold as a solid piece of material and
outer material 120M comprising a flowable material injected into
mold 600 and cured around the preformed piece comprising inner
material 600. The mold may comprise an upper portion and a lower
portion. 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 the same material, for example silicone. 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. With a step 440, the covering comprising the solid
inner component between first material 110M1 and third material
110M3 can be formed.
[0211] FIG. 4E shows formation of fenestrations in the covering
with energy. With a step 450 the covering as described in FIG. 4B
or 4D can be treated with energy 650, for example mechanical energy
or electromagnetic energy such as light energy to form the
fenestration extending through the covering. For example, the
fenestration can be removed from the mold and mechanically punched
or ablated with laser light energy to form the fenestration.
[0212] FIG. 4F shows spin coating of a hydrogel material on a
posterior surface of the covering. An amount of a curable hydrogel
forming material 660 as described herein can be deposited on the
posterior surface of the covering and spun with rotation 662 at
rate such that the coating moves away from a center of the covering
toward and outer boundary of the hydrogel material. The outer
boundary of the hydrogel material can be determined based on the
amount of curable material 660 and spin rate, and the curable
hydrogel material can be formulated to provide the desired
thickness as described herein, for example a substantially uniform
thickness within a range from about 1 .mu.m to about 100 .mu.m when
fully hydrated. With a step 460, the curable hydrogel forming
material 660 can be cured so as to provide the layer of hydrogel
material on the lower surface of the covering 100.
[0213] FIG. 4G shows chemical vapor deposition on the covering
having the hydrogel material formed thereon. The covering 100 can
be placed in a chemical vapor deposition chamber 670, and treated
with one or more forms of chemical vapor deposition as described
herein. With a step 460, the covering 100 can be coated with the
CVD to provide the wettable material on the surface of the
covering.
[0214] FIG. 4H shows the covering comprising 100 the hydrogel
material 120HG packaged in a container 680. The covering can be
sterilized, and can be packaged wet or dry, or combinations thereof
in container 680. For example, the covering can be placed with a
fluid comprising saline in the container. Alternatively, the
covering 100 can be dry packaged in container 680, for example.
With a step 480, the covering 100 can be placed on container 680
and the container sealed.
[0215] It should be appreciated that the specific steps illustrated
in method 400 provide a particular method of manufacturing a
covering, according to an embodiment 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 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.
[0216] A Method 500 of manufacturing covering 100 comprising a
contact lens to pump tear liquid may comprise one or more of the
following steps: [0217] 505--Provide first mold for optical
component [0218] 510--Inject first flowable material into first
mold [0219] 515--Cure first flowable material to form first optical
component [0220] 520--Remove first optical component from first
mold [0221] 525--Place first optical component in second mold
[0222] 530--Inject second curable material into second mold [0223]
535--Cure second flowable material to form second component [0224]
540--Remove second component from second mold [0225] 545--Place
second component in third mold [0226] 550--Inject third flowable
material into third mold [0227] 555--Cure third flowable to form
covering [0228] 560--Remove covering [0229] 565--Drill
fenestrations [0230] 570--Coat with wettable material
[0231] The rigidity and hardness of the molded covering can be
determined by one or more of the material hardness, the modulus or
the thickness. The molded covering may comprise a covering with an
inner center more rigid than the outer periphery, for example, and
the center can be thicker than edge. For example, the covering may
comprise a single piece covering with an inner portion thicker than
the outer portion such that the inner portion is more rigid than
the outer portion. Alternatively or in combination, an optically
clear inner portion can be molded; the inner portion placed in the
mold, and the covering molded to form the outer portion around the
inner portion. For example, the molded inner portion comprising
layer 110L2 of material 110M2 as described herein, and one or more
of layers 110L1 or 110L3 molded around layer 110L2.
[0232] It should be appreciated that the specific steps illustrated
in Method 500 provide a particular method of manufacturing a
covering, according to an embodiment 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 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.
[0233] Clinical studies have been undertaken and are contemplated
to show the pumping of the tear under the lens with blinking of the
eye in accordance with the embodiments described herein. A person
of ordinary skill in the art can determine empirically the
properties of covering 100 as described herein so as to provide
pumping of the tear fluid under the covering to provide one or more
of an extended wear contact lens or a covering for placement on the
cornea following PRK to improve vision and promote
reepithelialization.
[0234] As used herein, like reference characters indicate like
structures that can be combined in accordance with the teachings
and embodiments described herein.
[0235] In certain embodiments, methods for selecting ophthalmic
lenses are provided. The methods may be used to correct a
refractive error of an eye of a patient, the eye having a cornea
with an epithelium providing a refractive shape. In certain
embodiments, methods for selecting ophthalmic lenses comprise
determining a desired spherical power so as to mitigate any
spherical component of the refractive error of the eye of the
patient; and identifying, from among a plurality of alternative
ophthalmic lenses having differing spherical powers, the ophthalmic
lens corresponding to the desired spherical power. The identified
ophthalmic lens may then be selected and applied to the eye of the
patient to correct the spherical refractive error. The identified
ophthalmic lens has an anterior surface corresponding to the
desired optical power, and the anterior surface extends along an
inner portion of the ophthalmic lens.
[0236] The ophthalmic lenses have an inner portion for correcting
spherical refractive error and a peripheral portion for contacting
an optical tissue. The inner portion of the ophthalmic lens is
deformable and the peripheral portion of the ophthalmic lens is
deformable. The inner portion of the ophthalmic lens has a modulus
and a rigidity that is higher than the modulus and the rigidity of
the peripheral portion. The peripheral portion of the ophthalmic
lens has a shape suitable for engaging the eye outside the optical
region so as to support the inner portion in alignment with an
optical region of the eye. In certain embodiments, the peripheral
portion is configured to engage a tissue of the eye such as the
epithelium and to prevent or minimize motion of the ophthalmic
device with respect to the optical region of the eye. In certain
embodiments, the inner portion, the peripheral portion, or both the
inner and peripheral portions may deform or deflect upon blinking
of the eye.
[0237] In certain embodiments, the refractive shape of the
epithelium extends across the optical region of the eye such that
the refractive error comprises astigmatism and/or a high-order
optical aberration. In such embodiments, the posterior surface
extending across the optical region adjacent the eye may or may not
comprise a refractive shape so as to mitigate the astigmatism
and/or high-order aberration. Selection of a desired ophthalmic
lens is performed so that the peripheral portion of the ophthalmic
lens has a suitable shape to maintain a lenticular volume between
the posterior surface of the ophthalmic device and the surface of
the eye such as the epithelium. Before, during, and/or following
positioning of the ophthalmic device on the eye, the lenticular
volume fills with tear fluid such that the anterior shape of the
ophthalmic lens corrects the refractive error. Accordingly, in
certain methods, selecting an ophthalmic lens is performed so that
the peripheral portion has a suitable shape such that tear fluid
will fill a lenticular volume between the posterior surface and the
refractive shape of the eye so as to mitigate the astigmatism
and/or high-order aberration. Where tear fluid is disposed between
the contact lens and the eye, and where the lens has a refractive
index sufficiently close to that of the tear fluid, the refraction
of the eye may be largely independent of the shape the posterior
surface and/or lenticular volume, at least when the posterior
surface initially contacts the lens and/or the contact lens remains
disposed on the eye. In certain methods, identifying an ophthalmic
lens is independent of as least one member of the group a power of
the astigmatism; and orientation of the astigmatism about an
optical axis of the eye, and/or as strength of the high-order
aberration and/or a type of high-order aberration. As a consequence
of the lenticular volume as defined by posterior surface of the eye
and the refractive shape being filled with tear fluid, it is not
necessary to orient an axis or position of the ophthalmic device
with the eye.
[0238] Ophthalmic lens provided by the present disclosure may also
be used for treating presbyopia. Methods for treating presbyopia
comprise, for example, positioning an ophthalmic lens on an eye so
that an inner portion of the ophthalmic lens is disposed over the
optical region of the cornea of the eye, and supporting the inner
portion of the ophthalmic lens by engagement between a peripheral
portion of the ophthalmic lens and a tissue of the eye outside the
optical region. The inner portion of the ophthalmic lens and the
peripheral portion of the ophthalmic lens can be deformable such
that the inner portion has a modulus and rigidity that is greater
than the modulus and rigidity of the peripheral portion. To correct
for presbyopia, the inner portion comprises a presbyopia-mitigating
refractive shape. In certain embodiments, a presbyopia-mitigating
shape is selected from an add region, a multifocal shape, an
aspherical shape, and a combination of any of the foregoing. In
certain embodiments, the peripheral portion comprises one or more
radius of curvature configured to engage a tissue of the eye such
as the epithelium so as to prevent or minimize motion of the inner
portion with respect to the optical region of the cornea. The
anterior portion of ophthalmic lens and the posterior surface of
the eye define a lenticular volume that is configured to fill with
tear fluid. To facilitate filling and/or flow of the tear fluid a
plurality of fenestrations extending through the thickness of the
peripheral region may be disposed in the peripheral region. The
fenestrations are disposed so as to facilitate, in conjunction with
motion of the ophthalmic lens, transfer of tear fluid through the
lenticular volume. Such methods of treating presbyopia using an
ophthalmic lens provided by the present disclosure may not require
precise alignment of the ophthalmic lens with respect to the
eye.
[0239] Similarly, methods for correcting a refractive error of an
eye, such as astigmatism and/or spherical aberration, where the eye
has a cornea with an epithelium providing a refractive shape
extending a cross an optical region of the eye are also provided.
Methods for correcting a refractive error comprising positioning an
ophthalmic lens on the eye so that an inner portion of the
ophthalmic lens is disposed over the optical region of the cornea,
wherein a posterior surface of the positioned ophthalmic lens
extends adjacent the eye and has shape diverging from the
refractive shape of the epithelium so that a lenticular volume is
disposed between the posterior surface and the epithelium. A
peripheral portion of the ophthalmic lens may comprise a plurality
of fenestrations extending through the thickness of the peripheral
portion and allowing passage of tear fluid between the lenticular
volume and the posterior (outer) surface of the ophthalmic lens. In
such embodiments, the inner portion of the positioned ophthalmic
lens is supported by engagement of a peripheral portion of the
ophthalmic lens and a tissue of the eye such as the epithelium
outside the optical region. The peripheral portion is configured to
support the inner portion of the ophthalmic lens, to prevent or
minimize motion of the inner portion with respect to the optical
region of the eye, and to facilitate filling of the lenticular
volume with tear fluid.
[0240] The fenestrations may be disposed outside the optical region
of the ophthalmic lens and inward of a region of engagement between
the peripheral portion of the ophthalmic lens and a tissue of the
eye. The inner portion and the peripheral portion of the ophthalmic
lens are deformable, for example, deformable upon motion of an
eyelid and/or over locally protruding epithelial regions so as to
inhibit pain, such that the inner portion has a modulus and
rigidity that is higher than the modulus and rigidity of the
peripheral portion. In certain embodiments, the deformability of
the inner portion and the outer portion of the ophthalmic lens are
configured so that blinking of the eye induces flow of tear fluid
through the fenestrations into and out of the lenticular volume,
and that when the eye is not blinking the inner portion retains a
shape that corrects the refractive error of the eye.
[0241] In certain embodiments, the peripheral portion comprises one
or more radius of curvature configured to engage a surface of the
eye and thereby resist motion of the inner portion with respect to
the optical region of the eye. For example, in certain embodiments,
a peripheral portion comprises a plurality of radii of curvature
wherein the radii of curvature become smaller from the center of
the ophthalmic lens toward the periphery. In certain embodiments,
the engagement between the peripheral portion and the tissue
surface of the eye along the engagement region inhibits lateral
movement of the inner portion relative to the cornea during
blinking.
[0242] In certain embodiments, methods of correcting refractive
error provided by the present disclosure can, for example, mitigate
the refractive error, when viewing with the eye through the
anterior surface, substantially independent of a shape of the
lenticular volume throughout a range of astigmatic errors of at
least about 0.5 D, at least about 1.0 D, and in certain
embodiments, at least bout 1.5 D, and is independent of a
rotational orientation of the ophthalmic lens about a viewing axis
of the eye.
[0243] Methods provided by the present disclosure further comprise
methods of remodeling the shape of the epithelium of an eye. In
certain embodiments, methods for optically remodeling the relative
shape of the epithelium comprise positioning an ophthalmic lens on
the eye so that an inner portion of the ophthalmic lens is disposed
over the optical region of the cornea, wherein a posterior surface
of the positioned ophthalmic lens extends adjacent the eye and has
a shape diverging from the refractive shape of the epithelium so
that a lenticular volume is disposed therebetween; and supporting
the inner portion of the ophthalmic lens by engagement between a
peripheral portion of the ophthalmic lens and the eye outside the
optical region so that fluid fills the lenticular volume and
viewing with the eye through an anterior surface of the ophthalmic
lens mitigates the refractive error. In methods of remodeling the
shape of the epithelium to correct refractive error of the eye, the
ophthalmic lens often (though not always) does not comprise
fenestrations. The posterior surface of the ophthalmic lens defines
a refractive shape for correcting spherical power and when
positioned on the eye defines a lenticular volume with the surface
of the eye. Over time, the epithelium and/or underlying tissue of
the eye may fill or otherwise occupy some, most, or all of the
lenticular volume disposed over the optical region. As with other
embodiments an ophthalmic lens for use in remodeling the shape of
the epithelium comprises a deformable inner portion and a
deformable peripheral portion such that the inner portion has a
higher modulus and rigidity than that of the peripheral portion and
the peripheral portion is configured to engage a tissue surface of
the eye and to inhibit lateral movement of the inner portion with
respect to the optical region of the cornea.
[0244] In certain embodiments, methods of remodeling the refractive
shape of the epithelium mitigate the refractive error when viewing
with the eye through the anterior surface, substantially
independent of a shape of the lenticular volume throughout a range
of astigmatic errors of at least about 0.5 D, at least about 1.0 D,
and in certain embodiments, at least bout 1.5 D, and is independent
of a rotational orientation of the ophthalmic lens about a viewing
axis of the eye.
[0245] Furthermore, when the ophthalmic lens is removed from the
eye the optical remodeling of the epithelium mitigates the
refractive error of the eye by at least about 11/2 D at least about
8 hours, at least about 24 hours, and in certain embodiments, at
least about 48 hours, after removal of the ophthalmic lens from the
eye.
[0246] Certain embodiments provided by the present disclosure
comprise sets of alternatively selectable ophthalmic lenses for
correcting refractive errors of eyes of a population of patients.
Such sets of ophthalmic lenses may be used in the methods disclosed
herein. The plurality alternative ophthalmic lenses have differing
spherical powers representing different refractive corrections.
Each of the plurality of alternative ophthalmic lenses comprises an
anterior surface corresponding to an associated desired spherical
power, the anterior surface extending along an inner portion of the
ophthalmic lens, wherein the inner portion of the ophthalmic lens
is deformable; and a peripheral portion of the ophthalmic lens
extending radially outwardly from the inner portion, the peripheral
portion having a rigidity lower than that of the inner portion and
configured for engaging tissue outside the optical region so as to
support the inner portion in alignment with an optical region.
[0247] In certain embodiments, ophthalmic lenses suitable for use
in methods provided by the present disclosure comprise an inner
portion configured to be disposed over the optical region of the
cornea of an eye, and a peripheral portion configured to support
the inner portion of the ophthalmic lens by engagement between the
peripheral portion of a tissue of an eye such as an epithelium
disposed outside the optical region. The inner portion and the
peripheral portion are deformable such that the modulus and
rigidity of the inner portion is higher than that of the peripheral
portion. In certain embodiments, the peripheral portion comprises
one or more radii of curvature whereby the peripheral portion
engages a surface tissue of an eye to prevent or mitigate motion of
the inner portion with respect to the optical region of the cornea
during blinking.
[0248] For treatment of presbyopia, the inner portion of the
ophthalmic lens comprises a surface extending along the inner
portion comprising a presbyopia-mitigating refractive shape.
[0249] For treatment of spherical refractive error the surface
extending along the inner portion of the ophthalmic lens comprises
a shape configure to correct spherical refractive error.
[0250] In certain embodiments, the inner portion may be configured
to correct non-spherical refractive errors such as astigmatic
error, multifocal error, higher order aberrations, and custom
optically corrective functions such as pin holes.
[0251] Certain embodiments provided by the present disclosure
include coverings comprising an optical component and a coupling
component, the optical component comprising a first material having
a first modulus, and the coupling component comprising a second
material having a second modulus, wherein the first modulus is
greater than the second modulus. FIG. 5 shows covering 500,
comprising optical component 501 and coupling component 502.
[0252] In certain embodiments, covering 500 has a diameter 510 from
about 9 mm to about 16 mm, in certain embodiments, from about 10 mm
to about 15 mm, and in certain embodiments, from about 12 mm to
about 14 mm.
[0253] In certain embodiments, optical component 501 comprises a
center thickness from about 150 .mu.m to about 500 .mu.m, from
about 200 .mu.m to about 400 .mu.m, and in certain embodiments,
from about 250 .mu.m to about 350 .mu.m.
[0254] In certain embodiments, optical component 501 comprises a
first material having a first thickness 505 and a second material
having a second thickness 503. In such embodiments, the second
material may be disposed on the inner surface of optical component
501, e.g., the surface facing the cornea, and may be the same
material as the material forming coupling component 502. The second
material may have a thickness 503 from about 5 .mu.m to about 60
.mu.m, from about 10 .mu.m to about 50 .mu.m, and in certain
embodiments, from about 20 .mu.m to about 40 .mu.m. In such
embodiments, where optical component 501 comprises two materials,
the total thickness of the optical component may be from about 100
.mu.m to about 550 .mu.m, from about 200 .mu.m to about 450 .mu.m,
and in certain embodiments, from about 250 .mu.m to about 350
.mu.m.
[0255] In certain embodiments, optical component 501 comprises an
optically clear material having a modulus from about 10 MPa to
about 70 MPa, from about 20 MPa to about 60 MPa, from about 20 MPa
to about 50 MPa, and in certain embodiments from about 30 MPa to
about 40 MPa.
[0256] Optical component 501 may be configured to correct vision or
may not be configured to correct vision.
[0257] In certain embodiments, optical component 501 comprises a
material selected from silicone, silicone hydrogel, and a
combination thereof. In certain embodiments, optical component 501
comprises silicone, in certain embodiments, silicone hydrogel, and
in certain embodiments a combination of silicone and silicone
hydrogel.
[0258] In certain embodiments, optical component 501 comprises a
center thickness from about 150 .mu.m to about 500 .mu.m, a
diameter from about 3 mm to about 9 mm, a radius of curvature from
about 7 mm to about 12 mm, and a modulus from about 20 MPa to about
50 MPa.
[0259] In certain embodiments, coupling component 502 extends from
optical component 501 to an outer periphery 504, where the
thickness at the juncture with optical component 501 is the same as
or similar to that of optical component 502, and gradually tapers
toward outer periphery 504, wherein the thickness of the coupling
component at the periphery us from about 5 .mu.m to about 60 .mu.m,
from about 10 .mu.m to about 50 .mu.m, and in certain embodiments,
from about 20 .mu.m to about 40 .mu.m.
[0260] In certain embodiments, coupling component 502 comprises at
least one radius of curvature 512. For example, in certain
embodiments, coupling component 502 comprises a single radius of
curvature, and in certain embodiments, coupling component 502
comprises more than one radius of curvature such as two, three,
four, five, six, or more than six radii of curvature. The at least
one radius of curvature can be, for example, from about 5 mm to
about 15 mm, from about 6 mm to about 13 mm, from about 7 mm to
about 12 mm, and in certain embodiments, from about 6 mm to about
10 mm. The one or more radius of curvature 512 characterizing
coupling component 502 are less than the radius of curvature of
optical component 501.
[0261] In certain embodiments, coupling component 502 comprises a
material having a modulus from about 0.05 MPa to about 4 MPa, from
about 0.1 MPa to about 3 MPa, from about 0.1 MPa to about 2 MPa,
and in certain embodiment from about 0.2 MPa to about 1.5 MPa.
[0262] In certain embodiments, coupling component 502 comprises a
material selected from silicone, silicone hydrogel, and a
combination thereof. In certain embodiments, coupling component
comprises silicone, in certain embodiments, silicone hydrogel, and
in certain embodiments a combination of silicone and silicone
hydrogel.
[0263] In certain embodiments, coupling component 502 comprises a
plurality of fenestrations 509 extending through the thickness of
the coupling component. Coupling component 502 may comprise, for
example, from 1 to about 30 fenestrations, from 1 to about 20
fenestrations, and in certain embodiments, from about 1 to about 10
fenestrations. Fenestrations 509 may have any suitable shape to
provide egress of tear fluid. Suitable shapes include, for example,
circular, elliptical, oval, rectangular, square, slot, or
combination of any of the foregoing. Each of the plurality of
fenestrations 509 may have the same shape or at least some of the
fenestrations may have different shapes. In certain embodiments,
the fenestrations have a maximum dimension (hole size) from about
50 .mu.m to about 700 .mu.m, from about 100 .mu.m to about 500
.mu.m, and in certain embodiments, from about 200 .mu.m to about
400 .mu.m. Each of the fenestrations may have the same maximum
dimension or at least one of the fenestrations may have a different
dimension.
[0264] In certain embodiments, coupling component 502 does not
include fenestrations.
[0265] In certain embodiments, coupling component 502 comprises a
thickness tapering from the thickness of optical component 501 to a
thickness of about 30 .mu.m at the periphery 504 of the coupling
component; a plurality or radius of curvature from about 7 mm to
about 12 mm; and comprises a material having a modulus from about
0.1 MPa to about 2 MPa. In embodiments in which coupling component
502 comprises a plurality of radii of curvatures 512, the radius of
curvature decreases from the optical component toward the
periphery.
[0266] The covering, including optical component 501 and coupling
component 502, is configured to provide a seal to a tissue of an
eye such as an epithelium to thereby resist movement of the optical
component on an eye.
[0267] FIGS. 6A-6C show various lenses positioned on an astigmatic
eye. For each of FIGS. 6A-6C, the left image shows the
configuration of the first radial and the right image shows the
configuration of the second radial corresponding to the aspheric
projection 608. In FIG. 6A, the configuration corresponding to the
first radial includes the optical surface of the eye 601 and soft
refractive lens 603, which provides a focus on retina 605. In the
right image of FIG. 6A, the second radial direction corresponds to
a different refractive shape 602 that does not focus on the retina.
Soft, conformable ophthalmic lens 604 conforms to shape 602 and
thereby fails to correct the non-spherical aberration. FIG. 6B
shows aspheric correction using a hard, non-conformable ophthalmic
lens 606. Again, the first radial and the second radial correspond
to different optical shapes 601 and 602, respectively. Although
hard ophthalmic lens 606 corrects vision, the lens must be oriented
to correct the asymmetric profile of the eye. FIG. 6C schematically
shows correction of non-spherical aberration using ophthalmic
lenses and methods provided by the present disclosure (with the
peripheral portion of the eye and lens outside the optical region
omitted for simplicity). Ophthalmic lenses provided by the present
disclosure have a modulus and rigidity that is configured to
provide a lenticular volume between the optical surface of the eye
602 and the ophthalmic lens 607. For correction of presbyopia, the
ophthalmic lens is configured such that the lenticular volume fills
with tear fluid. As can be appreciated, it is not necessary to
orient ophthalmic lens 607 to correct non-spherical optical
aberrations.
[0268] Coverings provided by the present disclosure may be used as
platforms in a number of ophthalmic applications including, for
example, epithelium healing, spherical correction of astigmatism,
presbyopic solutions, epithelial reshaping, and dry eye.
[0269] In certain embodiments, coverings may be used to facilitate
epithelial healing. Epithelial defects can occur, for example, as
the result of PRK, filamentary keratitis, evaporative dry eye, or
physical injury to the eye. In these and other applications,
including applications in which vision is corrected,
[0270] When positioned on the eye of a patient, the inner surface
of the covering and the outer surface of the eye, which may
include, for example, the cornea, Bowman's membrane, and/or
epithelium, can define a chamber to facilitate healing and/or
growth of the epithelium. In such applications it is desirable that
a covering control moisture content and exhibit a high Dk to
facilitate extended wear. Using coverings and methods provided by
the present disclosure, complete epithelial regrowth following PRK
surgery can occur within about 48 hours, about 72 hours, 96 hours,
and in for certain patients, within about 1 week following PRK.
[0271] When used for spherical correction of corneal astigmatism,
coverings and methods provided by the present disclosure exhibit
the advantages of improved comfort compared to gas permeable
lenses, enhanced vision compared to soft contact lenses, and
reduced fitting time compared to toric and GP lenses. Coverings and
methods can, in certain embodiments, correct greater than 95% of
astigmatic errors, irregular astigmatism such as induced by trauma
or RK, and early kerotoconus.
[0272] In certain embodiments, a covering comprises an optical
component that corrects vision. Thus, in addition to spherical
correction, the optical component can be configured to support
multifocal, higher order aberration or custom optical designs such
as pin holes.
[0273] In epithelial reshaping applications, coverings and methods
provided by the present disclosure can be used to reshape the
epithelial during wear, and correct vision for a period of time
after the covering is removed from the eye. For example, to correct
myopia, a covering can be used to guide the epithelium toward the
periphery of the eye and to create a flatter center curve. To
correct hyperopia, a covering may be used to guide the epithelium
toward the center of the eye and to create a steeper center curve.
In certain embodiments, a covering can be used to induce
mulitfocality for vision correction by guiding the epithelium
toward a desired location or locations on a cornea by molding with
an aspheric optic. The induction of mulitfocality through
epithelial reshaping can be useful to correct vision in presbyopia
and myopia.
[0274] Coverings and methods provided by the present disclosure can
also be used to address dry eye. In such applications, the covering
material comprises a material such as silicone that has a low water
content and low water absorption, water evaporation from the eye
can be controlled and a tear or lubricant reservoir maintained.
EXAMPLES
[0275] Embodiments provided by the present disclosure are further
illustrated by reference to the following examples, which describe
the use of certain ophthalmic lenses provided by the present
disclosure. It will be apparent to those skilled in the art that
many modifications, both to materials, and methods, may be
practiced without departing from the scope of the disclosure.
Example 1
[0276] A subject requiring an optical correction of -2.63 Diopters
(OD) and -2.13 Diopters (OS) characteristic for a subject having
myopia wore ophthalmic lenses on both eyes for (very roughly) about
40 hours. The inner and peripheral radii of curvature for the
ophthalmic devices are provided in Table 1. After about 40 hours,
the ophthalmic lenses were removed and the amount of optical
correction (Diopters) need to correct vision was determined at
various times. The amount of optical correction (Diopters) needed
after the ophthalmic lens was removed from the subjects is
presented in Table 1.
TABLE-US-00004 TABLE 1 Amount of optical correction (Diopters)
needed after wearing an ophthalmic lens. Amount of Radii of
correction curvature for needed ophthalmic lens (prior to Inner
Peripheral shield Curve Curve Time following ophthalmic lens
removal wear) (degrees) (degrees) 5 min 2 hr 4 hr 8 hr 24 hr 30 hr
48 hr Subject -2.63 39.5 43.0 -0.63 +0.13 +0.13 NM -0.50 -0.75
-1.25 #1 OD Subject -2.13 39.5 41.5 -0.63 -0.13 NM NM 0.00 0.00
-2.38 #1 OS *NM = No Measurement
Example 2
[0277] A subject requiring an optical correction of +0.13 Diopters
(OD) and +0.25 Diopters (OS) characteristic for a subject having
hyperopia wore ophthalmic lenses on the right eye for (very
roughly) about 35 hours, and on the left eye for (very roughly)
about 17. The inner and peripheral radii of curvature for the
ophthalmic devices are provided in Table 2. After about the
specified number of hours, the ophthalmic lenses were removed and
the amount of optical correction (Diopters) need to correct vision
was determined at various times. The amount of optical correction
(Diopters) needed after the ophthalmic lens was removed from the
subjects is presented in Table 2.
TABLE-US-00005 TABLE 2 Amount of optical correction (Diopters)
needed after wearing an ophthalmic lens. Amount of Radii of
correction curvature for needed ophthalmic lens (prior to Inner
Peripheral shield Curve Curve Time following ophthalmic lens
removal wear) (degrees) (degrees) 5 min 2 hr 4 hr 8 hr 24 hr 30 hr
48 hr Subject +0.13 39.5 43.0 -2.38 -3.13 -3.37 -2.00 NM NM NM #2
OD Subject +0.25 39.5 41.5 -1.00 -1.25 NM NM 0.00 NM NM #2 OS *NM =
No Measurement
[0278] 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 1
TABLE-US-00006 [0279] TABLE B1 14 mm R1 R1B1 R1B2 R1B3 R1 C2
multicurve center BC 5-7 mm 7-9 mm 9-11 mm 13.5-14 mm SAG designs
(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-00007 TABLE B2 Flatter periphery design 14 mm R1 R1B1 R1B2
R1B3 R1 C2 multicurve Center BC 5-7 mm 7-9 mm 9-11 mm 13.5-14 mm
designs (D) K (D) K (D) K (D) K (D) SAG (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-00008 TABLE B3 Large shield (16 mm) R1B1 R1B2 R1B3
multicurve R1 5-7 mm 7-9 mm 9-10.5 mm 10.5-13 mm SAG designs center
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 *may not tangent with previous curve (may
insert an outer curve to help it flare)
TABLE-US-00009 TABLE B4 R1 center R1B1 R1B2 R1B3 R1C Multicurve BC
5-7 mm K 7-9 mm K 9-11 mm 13.5-14 mm CL designs (D) (D) (D) K (D) K
(D) SAG (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
* * * * *