U.S. patent application number 16/532148 was filed with the patent office on 2019-11-21 for contact lenses having a reinforcing scaffold.
The applicant listed for this patent is NexisVision, Inc.. Invention is credited to Jose D. Alejandro, Matt Clarke, Eugene de Juan, JR., Raymond Lum, Cary J. Reich, Kuangmon Ashley Tuan.
Application Number | 20190353930 16/532148 |
Document ID | / |
Family ID | 52130801 |
Filed Date | 2019-11-21 |
United States Patent
Application |
20190353930 |
Kind Code |
A1 |
de Juan, JR.; Eugene ; et
al. |
November 21, 2019 |
CONTACT LENSES HAVING A REINFORCING SCAFFOLD
Abstract
Ophthalmic lenses for correcting refractive error of an eye are
disclosed. Ophthalmic lenses include an inner optic portion having
a scaffold between an anterior portion and a posterior portion. The
scaffold is characterized by a substantially uniform thickness
formed from a material characterized by a modulus that his higher
than the modulus of the peripheral portion. Openings within the
scaffold are filled with a low modulus material. When applied to an
eye, the lenses are configured to provide one or more lenticular
volumes between the posterior surface of the lens and the cornea.
The disclosure further relates to methods of correcting refractive
errors of an eye such as astigmatism or spherical aberration using
the ophthalmic lenses.
Inventors: |
de Juan, JR.; Eugene; (San
Francisco, CA) ; Reich; Cary J.; (Los Gatos, CA)
; Clarke; Matt; (Mountain View, CA) ; Tuan;
Kuangmon Ashley; (Mountain View, CA) ; Lum;
Raymond; (El Cerrito, CA) ; Alejandro; Jose D.;
(Sunnyvale, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NexisVision, Inc. |
Menlo Park |
CA |
US |
|
|
Family ID: |
52130801 |
Appl. No.: |
16/532148 |
Filed: |
August 5, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15807985 |
Nov 9, 2017 |
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16532148 |
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15096442 |
Apr 12, 2016 |
9851586 |
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15807985 |
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14539698 |
Nov 12, 2014 |
9341864 |
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15096442 |
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61904992 |
Nov 15, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02C 7/049 20130101;
G02C 7/047 20130101; G02C 2202/16 20130101 |
International
Class: |
G02C 7/04 20060101
G02C007/04 |
Claims
1. An ophthalmic lens for correcting a refractive error of an eye,
wherein the ophthalmic lens comprising: an inner optic portion
configured to be disposed over an optical region of the cornea and
comprising a center portion configured so that a posterior surface
of the inner optic portion is characterized by a shape diverging
from a refractive shape of the cornea, wherein the center portion
comprises a scaffold; and a peripheral portion disposed radially
outward of the inner optic portion.
2. The ophthalmic lens of claim 1, wherein, the scaffold comprises
a scaffold material characterized by a scaffold modulus; the
peripheral portion comprises a peripheral material characterized by
a peripheral modulus; and the scaffold modulus is greater than the
peripheral modulus.
3. The ophthalmic lens of claim 2, wherein the scaffold modulus
ranges from 300 MPa to 3000 MPa.
4. The ophthalmic lens of claim 1, wherein the scaffold is
characterized by a substantially uniform thickness.
5. The ophthalmic lens of claim 4, wherein the substantially
uniform thickness ranges from 50 .mu.m to 500 .mu.m.
6. The ophthalmic lens of claim 1, wherein the scaffold comprises
one or more openings.
7. The ophthalmic lens of claim 1, wherein, the center portion is
characterized by a center volume; and the one are more openings
comprise from 20 vol % to 80 vol % of the center volume.
8. The ophthalmic lens of claim 1, comprising a filler material
filling the one or more openings in the scaffold.
9. The ophthalmic lens of claim 1, wherein the center portion is
disposed between an anterior portion and a posterior portion.
10. The ophthalmic lens of claim 9, wherein, the anterior portion
comprises an anterior material characterized by an anterior
modulus; the posterior portion comprises a posterior material
characterized by a posterior modulus; the scaffold comprises a
scaffold material characterized by a scaffold modulus; the filler
material is characterized by a filler modulus; and the anterior
modulus and the posterior modulus are less than the scaffold
modulus.
11. The ophthalmic lens of claim 10, wherein each of the anterior
material, the posterior material, the filler material, and the
peripheral material is the same material.
12. The ophthalmic lens of claim 10, wherein each of the anterior
material, the posterior material, the filler material, and the
peripheral material comprise a hydrogel.
13. The ophthalmic lens of claim 10, wherein each of the anterior
material, the scaffold material, the filler material, and the
posterior material are characterized by substantially the same
refractive index within +/-0.02.
14. The ophthalmic lens of claim 1, wherein the inner optic portion
is characterized by a maximum thickness from 50 .mu.m to 500
.mu.m.
15. The ophthalmic lens of claim 1, wherein the inner optic portion
is characterized by a rigidity from 1E9 MPa-.mu.m to 1E11
MPa-.mu.m.
16. The ophthalmic lens of claim 1, wherein the inner optic portion
is configured to maintain one or more lenticular volumes between a
posterior surface of the inner optic portion and the optical region
of the cornea.
17. The ophthalmic lens of claim 1, wherein the inner optic portion
is characterized by an oxygen transmissibility of at least 80 D
k/t.
18. The ophthalmic lens of claim 1, wherein the inner optic portion
comprises an anterior surface and a posterior surface wherein each
of the anterior surface and the posterior surface is characterized
by a spherical profile.
19. The ophthalmic lens of claim 1, wherein, the cornea is
comprises an optical axis; and the ophthalmic lens is configured to
correct refractive error independent of radial orientation with
respect to the optical axis.
20. The ophthalmic lens of claim 1, further comprising a plurality
of fenestrations, wherein the plurality of fenestrations is
disposed within the inner optic portion, within the peripheral
portion, or within both the inner optic portion and the peripheral
portion.
21. The ophthalmic lens of claim 1, wherein, the refractive error
of the eye comprises astigmatism; and each of the anterior surface
of the inner optic portion and the posterior surface of the inner
optic portion is radially symmetric.
22. A method for correcting a refractive error of an eye, the eye
having a cornea with a refractive shape extending across an optical
region of the cornea, the method comprising: positioning an
ophthalmic lens on the cornea so that an inner optic portion of the
ophthalmic lens is disposed over the optical region of the cornea,
wherein the ophthalmic lens comprises: an inner optic portion
configured to be disposed over the optical region of the cornea and
comprising a center portion configured so that a posterior surface
of the inner optic portion has a shape diverging from the
refractive shape of the cornea, wherein the center portion
comprises a scaffold; and a peripheral portion disposed radially
outward of the inner optic portion.
Description
[0001] This application is a Continuation of U.S. application Ser.
No. 15/096,442, filed on Apr. 12, 2016, now allowed, which is a
Continuation of U.S. application Ser. No. 14/539,698, filed on Nov.
12, 2014, Issued as U.S. Pat. No. 9,341,864, which claims benefit
under 35 U.S.C. .sctn. 119(e) of U.S. Provisional Application No.
61/904,992, filed on Nov. 15, 2013, which is incorporated by
reference in its entirety.
FIELD
[0002] This disclosure relates to ophthalmic lenses for correcting
refractive error of an eye. Ophthalmic lenses include an inner
optic portion having a scaffold between an anterior portion and a
posterior portion. The scaffold is characterized by a substantially
uniform thickness formed from a material characterized by a modulus
that is higher than the modulus of the peripheral portion. Openings
within the scaffold are filled with a low modulus material. When
applied to an eye, the lenses are configured to provide one or more
lenticular volumes between the posterior surface of the lens and
the cornea. The disclosure further relates to methods of correcting
refractive errors of an eye such as astigmatism or spherical
aberration using the ophthalmic lenses.
BACKGROUND
[0003] Hybrid or bimodular contact lenses, lenses having a
comparatively rigid central portion and a soft skirt or peripheral
portion are used to correct refractive error of the eye such as
astigmatism. Current products such as rigid gas permeable (RGP) and
soft toric lenses for correcting refractive error include a
cylindrical component in addition to any spherical corrective
component that must be determined for each patient and oriented
with respect to the optical region of the cornea to maintain
optimal vision correction. Features are incorporated into the lens
to maintain centration and radial orientation of the lens of the
eye during wear. Because of the need to fit and orient the
cylindrical corrective component, a large number of lenses must be
maintained in inventory and individually fit and selected for each
patient.
[0004] In light of the above, it is desirable to provide improved
contact lenses for vision correction. Ideally, these contact lenses
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. It is also desirable to
provide improved contact lenses for correcting refractive error
that only require a spherical fit and provide comfort and vision
correction as good as or better than current toric lens
products.
BRIEF SUMMARY
[0005] In a first aspect, ophthalmic lenses for correcting a
refractive error of an eye are provided, the ophthalmic lenses
comprising an inner optic portion configured to be disposed over an
optical region of the cornea and comprising a center portion
configured so that a posterior surface of the inner optic portion
is characterized by a shape diverging from a refractive shape of
the cornea, wherein the center portion comprises a scaffold; and a
peripheral portion disposed radially outward of the inner optic
portion.
[0006] In a second aspect, methods for correcting a refractive
error of an eye are provided, the eye having a cornea with a
refractive shape extending across an optical region of the cornea,
the method comprising positioning an ophthalmic lens on the cornea
so that an inner optic portion of the ophthalmic lens is disposed
over the optical region of the cornea, wherein the ophthalmic lens
comprises: an inner optic portion configured to be disposed over
the optical region of the cornea and comprising a center portion
configured so that a posterior surface of the inner optic portion
has a shape diverging from the refractive shape of the cornea,
wherein the center portion comprises a scaffold; and a peripheral
portion disposed radially outward of the inner optic portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIGS. 1A-1D show top, side, perspective and cross-section
views of an ophthalmic lens according to certain embodiments.
[0008] FIGS. 2A-2D show top, side, perspective and cross-section
views of a scaffold according to certain embodiments.
[0009] FIGS. 3A-3D show top, side, perspective and cross-section
views of a scaffold according to certain embodiments.
[0010] FIGS. 4A-4D show top, side, perspective and cross-section
views of a scaffold according to certain embodiments.
[0011] FIGS. 5A-5D show top, side, perspective and cross-section
views of a scaffold according to certain embodiments.
[0012] FIGS. 6A-6D show top, side, perspective and cross-section
views of a scaffold according to certain embodiments.
[0013] Reference is now made in detail to embodiments provided by
the present disclosure. The disclosed embodiments are not intended
to be limiting of the claims.
DETAILED DESCRIPTION
[0014] As used herein, mathematical equations and scientific
notation can be used to identify values in many ways understood by
a person of ordinary skill in the art. As used herein the symbol
"E" can be used to express an exponent in base 10, such that 1E1
equals 10, 2E1 equals 20, and 4E2 equals 400. 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.
[0015] As used herein, an on K fit of a device such as a contact
lens encompasses fitting the contact lens to the flattest meridian
of the cornea and the on K fit can be flatter than the flattest
meridian within about 1.5 D. For example, for a cornea having
keratometer values (K values) of about 44 D axis 90 and 43 D axis
180, the on K fit would provide a device having a curvature
corresponding to an optical power within a range from about 43 D 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 device
such that the tear liquid can be pumped in accordance with
embodiments as described herein.
[0016] The optical power of the cornea in Diopters (D) can be
related to the radius R of curvature of the cornea with the formula
D=(1.3375-1)/R, where 1.3375 corresponds to the index of refraction
of the tear fluid. 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.
[0017] Dk refers to oxygen permeability, i.e., the amount of oxygen
passing through a device such as a contact lens over a given period
of time and pressure difference conditions. Dk is express in units
of 10.sup.-11 (cm/sec)(mL O.sub.2)(mL.times.mm Hg), also known as a
barrer. Oxygen transmissibility can be expressed as Dk/t, where t
is the thickness of the structure such as a contact lens and
therefore Dk/t represents the amount of oxygen passing through a
contact lens of a specified thickness over a given set of time and
pressure difference conditions. Oxygen transmissibility has the
units of barrers/cm or 10.sup.-9 (cm/sec)(mL O.sub.2)(mL.times.mm
Hg).
[0018] The terms outer portion of a lens and peripheral portion of
a lens are used interchangeably. The outer or peripheral portion is
disposed radially around and connected to the inner portion of a
covering or contact lens. In general, the outer or peripheral
portion tapers from a thickness at the interface with the inner
portion toward the outer or peripheral edge of the covering or
contact lens. The outer or peripheral portion may be further
characterized by sub-portions characterized by, for example,
different radii of curvature, thickness, rigidity, and material.
The sub-portions may be configured radially around the center optic
portion. Furthermore, the outer or peripheral portion is typically
disposed outside the optical region of the cornea with the covering
or contact lens centered on the cornea of an eye. The inner portion
includes a central inner optic portion through which the eye sees.
The inner portion may have a diameter that is larger than the
diameter of the inner optic portion. The inner portion is also
referred to herein as the inner or optical component or button. The
outer portion is also referred to herein as the outer or coupling
component.
[0019] The posterior surface of a contact lens or portion refers to
a surface that is near to or faces the cornea during wear by a
patient. The anterior surface of a contact lens or portion refers
to a surface that is away from or faces away from the cornea during
wear by a patient.
[0020] Bimodulus contact lenses having an inner optic portion with
a material having a higher modulus than the material forming the
outer peripheral portion can provide refractive correction
independent of the spherical orientation on the cornea. The modulus
of a material forming the inner optic portion provides a
sufficiently rigid structure to provide a spherical posterior lens
surface. Any non-spherical portions of the cornea are effectively
spanned by the posterior lens surface to define lenticular volumes
between the posterior lens surface and the cornea. When filled with
tear fluid, the lenticular volumes form a tear lens. Because a
bimodulus lens is spherically symmetric, astigmatic error can be
corrected regardless of the spherical orientation on the cornea,
eliminating the need for alignment or orientation features.
[0021] To provide sufficient rigidity of the inner optic portion,
the material forming the inner optic portion can be relatively thin
and be characterized by a high modulus, or can be relatively thick
and be characterized by a lower modulus. Lower modulus materials
and thin contact lenses generally enhance comfort of contact lens
wear. To enhance comfort, a high modulus material may be covered
with layers of low modulus material. This approach has the
advantage that the high modulus material can be retained by and
disposed within a low modulus material.
[0022] Eye health is promoted by oxygen permeability. For contact
lenses, it is generally desirable that the oxygen permeability be
greater than about 80 Dk. This high oxygen permeability can be
difficult to obtain for high modulus materials and/or for thicker
material cross-sections.
[0023] To provide spherically symmetric contact lenses capable of
correcting astigmatic error, contact lenses are disclosed in which
the inner optic portion includes a center portion having a scaffold
formed from a high modulus material and characterized by a
substantially uniform thickness.
[0024] The scaffold of the center portion imparts sufficient
rigidity to the center optic portion to provide a spherical
anterior lens surface and a spherical posterior lens surface for
correcting refractive error.
[0025] FIGS. 1A-1D show various views of a contact lens having a
scaffold. FIG. 1D shows a cross-section of a contact lens having an
inner optic portion 101, peripheral portion 102, anterior surface
103, and posterior surface 104. Inner optic portion 101 includes
anterior portion 105, center portion 106, and posterior portion
107. Center portion 106 is characterized by a substantially uniform
thickness and is embedded between anterior portion 105 and
posterior portion 107. As suggested by FIG. 1D, anterior portion
105, posterior portion 107, and peripheral portion 102 may be
formed from the same material, and center portion 106 may be formed
from a different material. In certain embodiments, center portion
106 also includes openings, which are not shown in FIG. 1D. The
anterior surface 103 and the posterior surface 104 of the inner
optic portion are characterized by a spherically symmetric
profile.
[0026] A center portion may have the same diameter as the inner
portion, may have a diameter greater than that of the inner
portion, or may have a diameter smaller than that of the inner
portion. The inner portion may have a diameter that is larger than
the inner optic portion through which the eye sees.
[0027] In certain embodiments, the center portion is a solid
material and is characterized by a substantially uniform thickness.
In certain embodiments, the solid material is homogenous.
[0028] In certain embodiments, the center portion may be configured
with openings, holes, channels or other features such that the
center portion serves as a scaffold or structural support rather
than as a continuous section or button of homogeneous material.
[0029] The openings can serve several functions including, for
example, increasing oxygen permeability, increasing tear flow, and
enabling the use of a high modulus material in the inner portion
while maintaining a relatively thin cross-sectional profile.
Furthermore, the openings can be filled with another optical
material such as a low modulus material that can serve to retain
and thereby increase the mechanical integrity of the bimodulus
contact lens.
[0030] The openings in the center portion may be any suitable
configuration. Examples of suitable configurations are shown in
FIGS. 2A-6D. In general, the configuration of the openings is
selected to provide a suitable rigidity to the center optic
portion, to enhance vision, and to promote eye health.
[0031] FIGS. 2A-2D show a scaffold configuration in which round
openings having similar diameters are disposed throughout the
center portion. The round openings may be disposed in any suitable
configuration and may form a regular or irregular pattern. Each of
the round openings may have similar diameters, may have different
diameters, or may have a combination of diameters. Round openings
having different diameters may be disposed in certain regions of
the center portion. For example, the round openings toward the
central axis may have a larger diameter than those located toward
the outer edge of the center portion. In certain embodiments, the
openings are disposed to minimize any optical distortion to normal
vision and to optimize visual acuity. The cross-sectional profile
of any opening may have any suitable shape such as oval and are not
necessarily round.
[0032] In certain embodiments, the round openings may have a
diameter ranging from 10 .mu.m to 1000 .mu.m including, for
example, 50 .mu.m to 500 .mu.m, 100 .mu.m to 500 .mu.m, or 50 .mu.m
to 250 .mu.m. In certain embodiments, the openings may have at
least one dimension ranging from 10 .mu.m to 1000 .mu.m including,
for example, 50 .mu.m to 500 .mu.m, 100 .mu.m to 500 .mu.m, or 50
.mu.m to 250 .mu.m.
[0033] FIGS. 3A-3D show a scaffold configuration in which the
center portion includes a large-diameter opening located in the
center with smaller openings disposed toward the outer edge of the
scaffold. In such embodiments, the center opening may have a
diameter from 1 mm to 4 mm or other suitable diameter.
[0034] FIGS. 4A-4D show a scaffold having a plurality of smaller
openings located along circles centered around the center axis of
the scaffold. Notably, FIG. 4C also shows that the openings are
angled with respect to the cross-sectional thickness of the
scaffold. Thus, in certain embodiments, the openings may be
substantially perpendicular to the cross-sectional thickness of the
scaffold, and in certain embodiments, may be angled with respect to
the cross-sectional thickness of the scaffold.
[0035] FIGS. 5A-5D show a scaffold configuration in which the
center portion has wedge-shaped openings forming a hub-and-spoke
arrangement. As shown in FIGS. 5A-5D, the center portion includes
ten wedge-shaped openings. However, any suitable number of
wedge-shaped openings may be employed. For example, FIGS. 6A-6D
show a configuration in which the center portion includes four
wedge-shaped openings.
[0036] It can be appreciated that other configurations of openings
are possible. In certain embodiments it may be desirable that
openings be relatively large to facilitate manufacture and/or to
minimize the interface area between the scaffold and the material
in which the scaffold is embedded.
[0037] In certain embodiments, openings can be in the form of
concentric rings held together by ribs. In other embodiments, a
scaffold may include a central opening with structural support
provided concentric to the optic axis of the scaffold. In such
configurations, the scaffold can take the form of a concentric ring
or modified concentric ring disposed outside the inner optic
portion of the lens. In general, the number, dimensions, and
configuration of the openings in the scaffold can be selected to
provide a desired rigidity and minimize interference with normal
vision and optimize visual acuity. Manufacturing and reliability
can also be important to the selection of appropriate scaffold
designs.
[0038] The number, size, and/or shape of the openings may be
selected to provide sufficient rigidity and oxygen permeability to
the inner optic portion of the ophthalmic lens. The number, size,
and/or shape of the openings may also be selected to facilitate
manufacturing. For example, depending on whether the center portion
is fabricated using injection molding, compression molding, cast
molding, or other suitable molding technology, the design may be
selected to facilitate the manufacturability and quality of the
part.
[0039] The openings in the center portion may be distinguished from
openings used to enhance tear flow and oxygen permeability. Such
openings that extend through the thickness of a contact lens are
generally characterized by a diameter less than 100 .mu.m. In
contrast, the openings used to provide high modulus scaffolds of
the present disclosure are larger such that, in certain
embodiments, the scaffold itself is only a small portion of the
inner optic portion.
[0040] The center scaffold is primarily configured to provide
mechanical structure. In certain embodiments, the center scaffold
is not configured to provide an optical function.
[0041] In certain embodiments, the center scaffold section is
characterized by a substantially uniform thickness. A substantially
uniform thickness refers to a thickness that varies less than +/-2%
across the profile, +/-5% across the profile, and in certain
embodiments less than +/-10% across the profile, where percent is
based on the nominal thickness of the scaffold. In certain
embodiments, the center scaffold portion may be characterized by a
non-uniform thickness; however, the effect of the non-uniform
thickness is not to affect the optical properties of the inner
optic portion. For example, the center scaffold portion may be
thicker toward the edge or may be thicker toward the center.
However, the optical properties of contact lenses provided by the
present disclosure are determined by the spherically-shaped
anterior and posterior lens surfaces.
[0042] In certain embodiments, the anterior portion is
characterized by a thickness from about 25 .mu.m to about 250
.mu.m, the posterior portion is characterized by a thickness from
about 25 .mu.m to about 250 .mu.m, and in certain embodiments, both
the anterior portion and the posterior portion are characterized by
a thickness from about 25 .mu.m to about 250 .mu.m.
[0043] In certain embodiments, the scaffold can be characterized by
a thickness from about 50 .mu.m to about 300 .mu.m, from about 75
.mu.m to about 300 .mu.m, from about 100 .mu.m to about 275 .mu.m,
from about 125 .mu.m to about 250 .mu.m, and in certain
embodiments, from about 125 .mu.m to about 225 .mu.m.
[0044] In certain embodiments, a scaffold is characterized by a
curvature configured to fit within a smooth cross-section profile
of the contact lens. The scaffold may have a diameter smaller than
the optical region of the cornea, larger than the optical region of
the cornea, or about the same diameter as the optical region of the
cornea.
[0045] In general, the thickness, diameter, curvature, and design
of the scaffold are configured to maintain a spherically symmetric
posterior surface of the lens. The lens may deform upon blinking
but may sufficiently recover so as not to significantly affect
vision of the eye.
[0046] In certain embodiments, the maximum thickness of the inner
optic portion is from about 100 .mu.m to about 500 .mu.m, in
certain embodiments, from about 150 .mu.m to about 350 .mu.m, from
about 200 .mu.m to about 300 .mu.m, and in certain embodiments,
from about 225 .mu.m to about 275 .mu.m.
[0047] In certain embodiments, the anterior portion, the posterior
portion and/or the filler material is characterized by an oxygen
permeability from about 10 Dk to about 500 Dk, from about 50 Dk to
about 400 Dk, from about 50 Dk to about 300 DK, and in certain
embodiments from about 50 DK to about 100 Dk.
[0048] In certain embodiments, the material forming the scaffold is
characterized by an oxygen permeability from about 0 Dk to about
300 Dk, from about 0 Dk to about 100 DK, and in certain
embodiments, from about 0 Dk to about 50 Dk.
[0049] In certain embodiments, the high modulus scaffold represents
from about 20 vol % to about 80 vol % of the center portion, from
about 30 vol % to about 70 vol %, from about 30 vol % to about 60
vol %, and in certain embodiments, from about 30 vol % to about 50
vol % of the total volume of the center portion.
[0050] In certain embodiments, the modulus of the material forming
the scaffold ranges from 300 MPa to 3000 MPa, from 500 MPa to 2000
MPa, from 800 MPa to 1800 MPa, and in certain embodiments from 1000
MPa to 1400 MPa.
[0051] In certain embodiments, a center portion is characterized by
a rigidity from about 1E9 MPa-.mu.m.sup.3to 1E11 MPa-.mu.m.sup.3,
from 1E9 to 5E10 MPa-.mu.m.sup.3, from 1E9 MPa-.mu.m.sup.3to 2E10,
from 2E9 to 2E10 MPa-.mu.m.sup.3, from 4E9 MPa-.mu.m.sup.3 to 2E10
MPa-.mu.m.sup.3, from 6E9 MPa-.mu.m.sup.3 to 2E10 MPa-.mu.m.sup.3,
and in certain embodiments, from 8E9 MPa-.mu.m.sup.3 to 2E10 M
Pa-.mu.m.sup.3.
[0052] In certain embodiments, the contact lens is configured to
have a maximum thickness less than about 400 .mu.m and an inner
optic portion characterized by a rigidity from about 1E9
MPa-.mu.m.sup.3to about 1E11 MPa-.mu.m.sup.3.
[0053] In certain embodiments, the contact lens is configured to
have a maximum thickness less than about 350 .mu.m and an inner
optic portion characterized by a rigidity from about 1E9
MPa-.mu.m.sup.3to about 5E10 MPa-.mu.m.sup.3.
[0054] In certain embodiments, the contact lens is configured to
have a maximum thickness less than about 300 .mu.m and an inner
optic portion characterized by a rigidity from about 1E9
MPa-.mu.m.sup.3to about 2E10 MPa-.mu.m.sup.3.
[0055] The high modulus material is formed into a disc-like part or
scaffold that can be embedded in a soft material. The part made
from the high modulus material can be of substantially uniform
thickness across its diameter, meaning it has no optical power by
itself. The anterior and posterior surfaces of the inner optic
portion can be made from the low modulus material and dictate the
optics of the system. The scaffold may be a continuous structure
with smooth surfaces or it may be modified with uniform through
holes, non-uniform through holes, a spoke-like pattern, an
open-cell foam, or other pattern that permits gas flow while
maintaining structural integrity. The material may be removed such
that the through holes are oriented normal to the surface of the
scaffold or diagonally oriented at any angle. The open space
created by removing material from the scaffold can be filled with a
low modulus material. This will allow for the use of low oxygen
permeable materials as the high modulus material. The lower the
oxygen permeability of the rigid material, the more material can be
removed in order to create a part with sufficient oxygen
permeability. As more material is removed from the scaffold, its
ability to reinforce the optical shape formed by the soft material
can decrease. Therefore, a balance can be made in material modulus
and oxygen permeability to design an oxygen permeable reinforcing
structure made from the high modulus material. Oxygen
transmissibility of an inner optic portion having a rigid scaffold
and low modulus anterior, posterior and filling portions can be
estimated using the Equation (1) and Equation (2):
Dk t = 100 * ( s b ( t a Dk a + t b Dk b + t d Dk d ) + s c ( t a
Dk a + t c Dk c + t d Dk d ) ) ( 1 ) Rigidity = t t 3 ( E a * f a +
s a * E b * f b + s c * Ec * f c + E d * f d ) ( 2 ) ##EQU00001##
[0056] Dk.sub.x=Oxygen Permeability of material "x" (Fatt Units)
[0057] t.sub.x=thickness of material "x" (microns) (t.sub.t=total
thickness of system) [0058] f.sub.x=t.sub.x/t.sub.t [0059]
s.sub.x=fractional amount of material "x" that exists across
thickness t.sub.x (for an un-modified disc: s.sub.x=1) [0060]
E.sub.x=Young's Modulus of Material "x."
[0061] The results of example calculations are shown in Table
1.
[0062] In general, low modulus materials are characterized by high
oxygen permeability such as oxygen permeability from about 10 Dk to
about 500 Dk, and in certain embodiments from about 100 Dk to 400
Dk.
[0063] In general, high modulus materials are characterized by low
oxygen permeability such as less than 300 Dk, less than 200 Dk,
less than 100 Dk, less than 50 Dk, and in certain embodiments, less
than 10 Dk.
[0064] In general, for a continuous wear contact lens it is
desirable that the oxygen transmissibility be at least 50 Dk/t, at
least 80 Dk/t, at least 90 Dk/t, and in certain embodiments, at
least 100 Dk/t.
[0065] To reduce optical artifacts it is desirable that the
refractive index of the material forming the scaffold be closely
matched to the refractive index of the material filling the
openings and forming the anterior portion and the posterior portion
of the inner optic portion. For example, in certain embodiments,
the difference in the refractive index is less than 0.03, less than
0.025, less than 0.02, less than 0.015, less than 0.010 and in
certain embodiments, less than 0.005.
[0066] The material forming the scaffold and the material forming
the anterior portion, posterior portion, and the filler portion
should have similar indices of refraction in order to minimize
internal reflections within the part. For example, a Boston EO RGP
has a refractive index of 1.429 (Modulus=1600 MPa) can be used with
a soft material, for example lotrafilcon A that has a refractive
index of 1.43. If using the Boston Equalens II (refractive
index=1.423) a soft material such as hefilcon B (refractive index
1.42) can be used.
[0067] The materials forming the scaffold and the materials filling
the openings in the scaffold, the anterior portion, and the
posterior portion of the inner optic portion of the contact lens
can be selected to have similar chemistries such that covalent
bonds form between the dissimilar materials. For example, the low
modulus material and the high modulus material forming the scaffold
may be silicon-based or may contain silicon. Thus, in certain
embodiments, the scaffold may be formed from a blend of silicon and
other material.
[0068] Alternatively, to ensure adhesion between the scaffold and
the surround material the surface of the scaffold may be treated to
enhance adhesion such as plasma treatment or other suitable
treatment method.
[0069] Contact lenses formed from dissimilar hydrous material can
be difficult to manufacture because of differential swelling of the
materials during hydration. Therefore, it is desirable to select
the low modulus and high modulus materials to exhibit similar
swelling when hydrated. Alternatively, to avoid or at least
minimize problems associated with differential swelling, the low
modulus materials and the high modulus materials can be selected to
be non-hydrous such that the materials exhibit minimal swelling
when hydrated.
[0070] Eye health is promoted by the presence and flow of tear
fluid along the surface of the cornea. Because the contact lenses
provided by the present disclosure are spherically symmetric and
are configured to correct astigmatic error independent of the
orientation on the cornea, the lenses can freely move and thereby
promote the flow and exchange of tear fluid across the surface of
the cornea. The scaffold can further help to center the contact
lens on the cornea following blinking. Alternatively, or in
addition to, fenestrations may be provided through the contact lens
proximate to the inner optic region and/or in the peripheral region
to further promote the flow and exchange of tear fluid. The
fenestrations may further serve to maintain a reservoir of tear
fluid within the lenticular volume and thereby support the
spherical profile of the posterior surface of the contact lens.
[0071] The base curve and the spherical power of the lens can be
independent of the shape of the scaffold.
[0072] The material forming the center scaffold portion is
characterized by a refractive index similar to that of the other
materials forming the inner optic portion of the contact lens. In
certain embodiments, the material forming the center scaffold
portion is characterized by a refractive index that is similar to
that of the cornea such as, for example, from about 1.4 to about
1.5, from about 1.42 to about 1.48, and in certain embodiments,
from about 1.43 to about 1.47.
[0073] The openings in the center scaffold portion are filled with
an interstitial material. The interstitial material will generally
be characterized by a lower modulus and a higher oxygen
permeability than the modulus and oxygen permeability of the center
scaffold material. In addition, the material filling the openings
in the scaffold will have a refractive index that is substantially
similar to the material forming the scaffold. For example, in
certain embodiments the material filling the openings in the
scaffold will be characterized by a refractive index from about 1.4
to about 1.6.
[0074] In addition to the center scaffold portion, the inner optic
portion includes at least one layer of material anterior to the
center scaffold portion, and at least one layer of material
posterior to the center scaffold portion. The materials located
anterior and posterior to the center scaffold portion may be the
same or may be different materials. For ease of fabrication, in
certain embodiments, the materials located anterior and posterior
to the center scaffold portion can be the same materials.
[0075] In certain embodiments, the material filling the openings in
the scaffold will be the same as the material forming the anterior
and/or posterior materials of the inner optic portion.
[0076] In certain embodiments, the material forming the anterior
and/or posterior materials of the inner optic portion will extend
to the peripheral portion and in certain embodiments will be the
same material as the peripheral portion.
[0077] Material forming the anterior and/or posterior portions of
the inner optic portion may be characterized by a modulus from 0.1
MPA to 10 MPa, from 0.1 MPa to 5 MPa, or in certain embodiments
from 0.1 to 2 MPa. In certain embodiments, the filler material in
the scaffold openings may be characterized by a modulus from 0.1
MPA to 10 MPa, from 0.1 MPa to 5 MPa, or in certain embodiments
from 0.1 to 2 MPa.
[0078] In certain embodiments, the material forming the anterior
and/or posterior portions of the inner optic portion may be formed
from a material characterized by a high oxygen permeability (Dk,
cmmL O.sub.2/secmLmm Hg) such as from 100.times.10.sup.-11 to
500.times.10.sup.-11, from 200.times.10.sup.-11 to
500.times.10.sup.-11, from 250.times.10.sup.-11 to
450.times.10.sup.-11, from 300.times.10.sup.-11 to
400.times.10.sup.-11, and in certain embodiments, about 350.
[0079] In certain embodiments, devices provided by the present
disclosure are characterized by a high oxygen transmissibility
(Dk/t) such as at least about 50.times.10.sup.-9, at least about
80.times.10.sup.-9, at least about 100.times.10.sup.-9, and in
certain embodiments, at least about 120.times.10.sup.-9.
[0080] The material forming the anterior portion, posterior
portion, and/or filler portion of the inner optic portion may be
hydrous or in certain embodiments may be anhydrous. An anhydrous
material refers to a material having a water content, when fully
hydrated, less than 10 wt %, less than 5 wt %, and in certain
embodiments, less than 2 wt %. A hydrous material refers to a
material having a water content, when fully hydrated, greater than
10 wt %.
[0081] In certain embodiments, a lens may comprise silicone or
silicone hydrogel having a low ionoporosity. For example, a device
may comprise silicone hydrogel or silicone comprising a low ion
permeability, and the range of water can be from about 5% to about
35%, such that the Dk is 100.times.10.sup.-" or more. In certain
embodiments, the low ion permeability may comprise an Ionoton Ion
Permeability Coefficient of no more than about 0.25.times.10.sup.-3
cm.sup.2/sec, for example no more than about 0.08.times.10.sup.-3
cm.sup.2/sec.
[0082] An ophthalmic lens may comprise a wettable surface coating
disposed on at least the upper side (anterior surface) of the
device, such that the tear film of the patient is smooth over the
device 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
create a contact angle no more than about 80 degrees. For example
the coating may create a contact angle no more than about 70
degrees, and the contact angle can be within a range from about 55
degrees 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 device, i.e., on the
anterior and posterior surface of the ophthalmic lens. The upper
surface may comprise the wettable coating extending over at least
the inner optic portion.
[0083] A wettable coating may comprise one or more suitable
materials. For example, the wettable coating may comprise
polyethylene glycol (PEG), and the PEG coating can be disposed on
Parylene.TM.. Alternatively, the wettable coating 134 may comprise
a plasma coating, and the plasma coating may comprise a luminous
chemical vapor deposition (LCVD) film. For example, the plasma
coating may comprise at least one of a hydrocarbon, for example,
CH.sub.4, O.sub.2 or fluorine containing hydrocarbon, for example,
CF.sub.4 coating. Alternatively or in combination, a wettable
coating may comprise a polyethylene glycol (PEG) coating or
2-hydroxyethylmethacrylate (HEMA). For example, a wettable coating
may comprise HEMA disposed on a Parylene.TM. coating, or a wettable
coating may comprise N-vinylpyrrolidone (NVP) disposed on a
Parylene.TM. coating.
[0084] In certain embodiments, ophthalmic lenses provided by the
present disclosure are configured to correct refractive error such
as astigmatism. The lenses provide a smooth spherical anterior
surface and minimize lens-induced distortions by reducing flexure
of the inner optical portion and by maintaining lens centration
during wear. Reduced flexure of the inner optical portion can in
part be accomplished by increasing the rigidity of the inner
portion and by creating a tear lens. Centration of the inner
optical portion minimizes astigmatic and prismatic effects caused
by tilting of the optic and also minimizes edge distortion.
[0085] Ophthalmic lenses provided by the present disclosure can
achieve visual correction at least equivalent to that of soft toric
contact lenses and achieve a superior comfort level compared to
soft toric contact lenses. Furthermore, because the ophthalmic
lenses provided by the present disclosure are radially symmetric,
fitting to an eye of the patient involves only accommodating the
spherical correction and an inventory of lenses for correcting
cylindrical error is not required.
[0086] Ophthalmic lenses provided by the present disclosure include
an inner optic portion configured to be disposed over the optical
region of the cornea and a peripheral or outer portion that is
disposed radially outward of the inner portion. An ophthalmic lens
includes a posterior surface that extends along the inner portion
of the lens and is adjacent an eye when applied to an eye of a
patient. An ophthalmic lens also includes an anterior surface that
extends along the outer surface of the lens and opposite the
posterior surface. In general, the inner portion of a lens is
configured to improve vision and the peripheral portion is
configured to improve comfort. However, the configuration of the
inner portion can also play a role in determining patient comfort,
and the peripheral portion, at least in part, by maintaining
centration of the inner optical portion on the optical portion of
the cornea during wear enhances the visual outcome.
[0087] The inner optical portion of a lens is configured so that
engagement of the posterior surface against the eye deforms the
posterior surface so that the posterior surface of the inner
portion has a shape diverging from the refractive shape of the
epithelium and optical portion of the cornea. The anterior surface
of the inner portion of the ophthalmic lens provides a spherical
surface to correct a patient's vision.
[0088] In certain embodiments, the inner optical portion of a lens
is characterized by a diameter from about 5 mm to about 10 mm, from
about 7 mm to about 9 mm, from about 7.5 mm to about 8.5 mm, from
about 7.8 mm to about 8.2 mm, and in certain embodiments, about 8
mm. The anterior inner portion of a lens is characterized by a
substantially spherical profile without a cylindrical
component.
[0089] In certain embodiments, the material forming a device
including both the inner and outer portions have low water content
and is characterized by low water or ion permeability. In certain
embodiments, the water content is less than about 5%, less than
about 4%, and in certain embodiments, less than about 3%. In
certain embodiments, the material forming a device has a water
content less than about 1%, less than about 0.6%, and in certain
embodiments, less than about 0.3%. In certain embodiments, the
material less than about 0.4.times.10.sup.-6 cm.sup.2/sec, less
than about 0.2.times.10.sup.-6 cm.sup.2/sec, and in certain
embodiments, less than about 0.1.times.10.sup.-6 cm.sup.2/sec.
[0090] A peripheral portion is disposed radially outward of the
inner portion of an ophthalmic lens. In general, the peripheral
portion retains the inner portion and is characterized by
approximately the same thickness as the inner portion at the
interface between the inner and peripheral portions, and the
thickness of the peripheral portion tapers toward the peripheral
edge. In certain embodiments, the diameter of the peripheral edge
is from about from about 12 mm to 16 mm, 13 mm to about 16 mm, from
about 13.5 mm to about 15.5 mm, from about 14 mm to about 15 mm,
and in certain embodiments, from about 14.2 mm to about 14.8
mm.
[0091] The peripheral portion is characterized by a lower rigidity
than the inner portion and can be formed from a material having a
lower modulus than that of the inner portion. In certain
embodiments, the material forming the peripheral portion is
characterized by a modulus from about 0.5 MPa to about 2.0 MPa,
from about 0.8 MPa to about 1.7 MPa, from about 1.0 MPa to about
1.4 MPa, and in certain embodiments, about 1.2 MPa.
[0092] The peripheral portion is configured to provide tear flow
between the anterior surface of the device and the epithelium. In
certain embodiments, the peripheral portion comprises a plurality
of fenestrations extending from the anterior to the posterior
surface of the peripheral portion. In certain embodiments, the
plurality of fenestrations are disposed at a radius from a central
optical axis of the ophthalmic lens such as for example, at a
radius proximate to the interface between the inner portion and the
peripheral portion. The plurality of fenestrations may be
symmetrically or asymmetrically disposed. The fenestrations may be
configured to pump tear liquid between the peripheral portion and
the epithelium when the eye blinks so as to maintain a tear layer
between the posterior surface of the lens and the epithelium and/or
across the anterior surface of the lens. In certain embodiments,
the plurality of fenestrations may be configured to facilitate
removal of the lens from the eye. In certain embodiments, the
plurality of fenestrations may be configured to facilitate air
dissipation if air bubbles are trapped underneath the lens. In
certain embodiments, the plurality of fenestrations facilitates the
removal of air bubble entrapped within any lenticular volumes
following application of a lens to a patient's eye. The plurality
of fenestrations may facilitate both removal of the lens form the
eye and dissipation of air bubbles. In certain embodiments, the
plurality of fenestrations improves the reproducibility of visual
outcome in a population of patients wearing the lens compared to
the visual outcome in a population of patients wearing a comparable
lens without fenestrations.
[0093] In certain embodiments, the inner portion, the peripheral
portion, or both the inner and peripheral portions of an ophthalmic
lens provided by the present disclosure are radially symmetric. In
certain embodiments, the anterior surface of the inner portion and
the posterior surface of the inner portion are radially
symmetric.
[0094] In certain embodiments of ophthalmic lenses provided by the
present disclosure, the inner portion and the peripheral portion
are configured to allow movement of the lens relative to the eye in
response to blinking of the eye. In such embodiments, an ophthalmic
lens is configured such that the inner optical portion centers on
the optical portion of the cornea following blinking. During
blinking the inner portion, the peripheral portion, or both the
inner and peripheral portions may deform and/or move with respect
to the center optical axis of the cornea. When an ophthalmic lens
is worn by a patient, depending at least in part by the shape of
the patient's eye and the configuration of the lens, the ophthalmic
lens may move during blinking or may exhibit only micro-movement.
However, in certain embodiments, a lens is not configured to resist
movement such that, for example, the peripheral edge of the lens is
not configured to fixedly engage the epithelium or sclera such that
the inner portion resists movement relative the cornea.
[0095] In certain embodiments of ophthalmic lenses provided by the
present disclosure, the inner portion and the peripheral portion
are configured to provide a tear fluid flow between the peripheral
portion of the ophthalmic lens and the epithelium.
[0096] The peripheral portion of a lens can be tapered toward the
peripheral edge. The taper may be continuous or discontinuous. The
peripheral portion may be flared outward toward the peripheral edge
and is referred to as a modified heeled configuration. A
cross-sectional profile of a lens is determined by the inner
portion characterized by a substantially constant thickness and the
shape of the taper of the peripheral portion. In general, the
cross-sectional shape of an ophthalmic lens is configured to
correct refractive error of any eye, center the lens on the optical
portion of the cornea, facilitate motion of the lens with respect
to the eye, provide flow of tear liquid between the posterior
surface of the lens and epithelium, and to provide comfort to a
patient wearing the lens. The ability of the lens to move, provide
a fluid layer, and exchange tear fluid facilitates eye health and
improves comfort for extended wear.
[0097] Ophthalmic lenses provided by the present disclosure include
features intended to confer attributes of benefit to a person
wearing the lens. For example, the semi-rigid inner optic portion
provides a near spherical anterior surface and maintains the
intended near spherical curvature during wear. By minimizing
toricity and irregularities of the anterior surface of the lens and
minimizing flexure, the lens provides good vision. Vision and
health of the eye are enhanced by the presence of fenestrations.
Furthermore, the semi-rigid inner optic portion is sufficiently
flexible to accommodate a range of corneal curvatures and is able
to mask corneal toricity by forming a lenticular tear volume
between the posterior surface of the lens and the cornea. In
certain embodiments, in part depending on the shape of a cornea,
one or more lenticular volumes are formed between the posterior
surface of the lens and the cornea.
[0098] The fenestrations provide a supply of fluid between the
posterior surface of the lens and the epithelium of the eye to
maintain a tear layer, which supports the intended curvature of the
lens to provide good vision. Fenestrations also maintain eye health
by allowing for rapid tear exchange to circulate metabolic waste
and to transmit oxygen to the tear layer. Fenestrations also
prevent a lens from creating vacuum seal to the eye, allowing the
lens to move on the eye and facilitating lens removal.
[0099] The materials forming the outer portions of the inner optic
portion and the outer peripheral portion can have a low Young's
modulus that improves patient comfort. Also, a thickness of a
material along the posterior surface of the inner optic portion
having a Young's modulus less than the modulus of the material
forming the inner optic portion may provide additional comfort. In
addition to the effect of the fenestrations, eye health is further
enhanced by the use of silicones and/or silicone hydrogels to form
the lens. Silicones and/or silicone hydrogels are physiologically
compatible and can provide high oxygen permeability and ion
permeability.
[0100] In certain embodiments, ophthalmic lenses provided by the
present disclosure include a plurality of fenestrations. The
fenestrations can provide a supply of tear fluid to establish and
maintain a tear volume between the posterior surface of the inner
optic portion and the cornea to support the intended lens
curvature, allow exchange of tear fluid to circulate metabolic
waste, and to supply and maintain a high oxygen content at the
surface of the cornea.
[0101] Fenestrations can be disposed within the inner optic portion
of the ophthalmic lens, within the peripheral portion of the
ophthalmic lens, or within both the inner optic and peripheral
portions of the ophthalmic lens. In certain embodiments, the
fenestrations may be disposed along one or more rings situated at a
radius from the central axis of the ophthalmic lens. Each ring may
include from one (1) to twenty (20) fenestrations. In certain
embodiments, fenestrations may be disposed along one or more rings
disposed at different radii from the central axis of the ophthalmic
lens.
[0102] For example, in certain embodiments the plurality of
fenestrations can be disposed at a combination of a first radius, a
second radius, a third radius, and a fourth radius from a central
optical axis of the ophthalmic lens, wherein: the first radius is
disposed within the inner optic portion and from 0.5 mm to 1.0 mm
from an interface between the inner optic portion and the
peripheral portion; the second radius is disposed within the
peripheral portion and from 0.5 mm to 1.5 mm from the interface
between the inner optic portion and the peripheral portion; the
third radius is disposed within the peripheral portion and from 1.5
mm to 2.5 mm from the interface between the inner optic portion and
the peripheral portion; and the fourth radius is disposed within
the peripheral portion and from 0.5 mm to 2.5 mm from an edge of
the peripheral portion.
[0103] In certain embodiments, an ophthalmic lens may comprise
anywhere from 1 to 20 fenestrations. The location and cross-section
of certain fenestrations may be configured to pump tear liquid
between the posterior surface of the lens and the epithelium when
the eye blinks. Circulation of tear fluid can help to maintain eye
health. Certain fenestrations may be configured to maintain a tear
layer between the eye and one or more portions of the posterior
surface of the inner optic portion. The tear layer can help to
maintain health of the eye, can help to provide comfort, and can
facilitate removal of the lens from the eye. Certain portions of an
ophthalmic lens may conform to the cornea while other portions may
create one or more lenticular volumes between the posterior surface
of a lens and the cornea. Certain fenestrations can be configured
to maintain tear fluid within the lenticular volumes. The
lenticular volumes in conjunction with the ophthalmic lens form a
tear lens for improving vision. Fenestrations located proximate to
the interface between the inner optic portion and the peripheral
portion may serve to maintain tear fluid within lenticular volumes.
Certain fenestrations such as those located within the peripheral
portion may be configured to maintain eye health and to facilitate
removal of the lens from the eye.
[0104] In certain embodiments, a plurality of fenestrations is
disposed within the inner optic portion to provide for sufficient
tear flow beneath the inner optic portion to establish and maintain
a lenticular tear volume between the posterior surface of the inner
optic portion and the cornea. The tear volume maintains the
spherical shape of the lens on the eye to improve patient vision.
While certain portions of the posterior surface of the lens can
conform to the surface of the cornea, where the cornea is
characterized by toric and/or cylindrical irregularities, the inner
optic portion is sufficiently rigid that it bridges the corneal
irregularities creating one or more lenticular volumes which are
filled with tear fluid.
[0105] The number and location of the fenestrations can be
configured to achieve one or more of these benefits.
[0106] In certain embodiments, the tear volume beneath certain
portions of the inner optic portion of the ophthalmic lens can be
maintained by fenestrations located just outside the diameter of
the inner optic portion of the lens.
[0107] Fenestrations located within the peripheral portion of the
lens can maintain eye health, provide tear film that facilitates
motion of the lens on the cornea, and/or facilitate removal of the
lens from the eye.
[0108] Fenestrations may be any suitable shape, be situated and any
suitable orientation with respect to the cross-sectional profile of
the lens. In certain embodiments, fenestrations are characterized
by a circular cross-section having a diameter from about 50 .mu.m
to about 300 .mu.m, from about 80 .mu.m to about 250 .mu.m, and in
certain embodiments, from about 100 .mu.m to about 200 .mu.m.
[0109] In certain embodiments, ophthalmic lenses provided by the
present disclosure include a sag height from about 3 mm to about 5
mm, in certain embodiments, from about 3.5 mm to about 4.5 mm, and
in certain embodiments, from 3.5 mm to about 4.2 mm. The sag height
refers to the distance from the center of the lens to a line
extending from the peripheral edge of a lens. For a particular
optic curvature, lenses may be provided with several different sag
heights to accommodate different eyeball sizes among a general
population of patients. For example, lenses having particular optic
curvature may be provided with three different sag heights from a
nominal sag height of 4.0 mm in steps from about 0.15 mm to 0.3 mm.
For example, for lenses having a particular optic curvature, lenses
having sag heights of 3.7 mm, 4.0 mm, and 4.3 mm can be provided.
In certain embodiments, for lenses having a particular optic
curvature, lenses having sag heights of 3.85 mm, 4.0 mm, and 4.15
mm; sag heights of 3.8 mm, 4.0 mm, and 4.2 mm; and in certain
embodiments, sag heights of 3.75 mm, 4.0 mm, and 4.25 mm, can be
provided.
[0110] In certain embodiments, an ophthalmic lens for correcting a
refractive error of an eye, the eye having a cornea with a
refractive shape extending across an optical region of the eye,
comprises: an inner optic portion configured to be disposed over
the optical region of the cornea; a posterior surface extending
along the inner optic portion adjacent the eye when the inner
portion is disposed over the optical region, the inner optic
portion configured so that engagement of the posterior surface
against the eye deforms the posterior surface and so that the
posterior surface has a shape diverging from the refractive shape
of the cornea; a peripheral portion of the ophthalmic lens disposed
radially outward of the inner optic portion; and an anterior
surface of the ophthalmic lens extending along the inner optic
portion opposite the posterior surface configured to mitigate the
refractive error; wherein, the inner optic portion is characterized
by an inner rigidity and the peripheral portion is characterized by
a peripheral rigidity; the inner rigidity is greater than the outer
rigidity.
[0111] In certain embodiments of an ophthalmic lens, the inner
optic portion is characterized by a substantially spherical
profile.
[0112] In certain embodiments of an ophthalmic lens, the refractive
error of the eye includes a cylindrical error; and the inner optic
portion is characterized by a substantially spherical surface so
that correction of the cylindrical error by the lens is primarily
effected by the divergence of the shape of the inner optic portion
from the refractive shape of the cornea.
[0113] In certain embodiments of an ophthalmic lens, the inner
optic portion and the peripheral portion are configured to allow
movement relative to the eye.
[0114] In certain embodiments of an ophthalmic lens, the inner
optic portion and the peripheral portion are configured to provide
a tear fluid flow between the inner optic portion of the ophthalmic
lens and the cornea.
[0115] In certain embodiments of an ophthalmic lens, the refractive
error of the eye comprises astigmatism; and the anterior surface of
the inner optic portion and the posterior surface of the inner
optic portion are radially symmetric.
[0116] In certain embodiments of an ophthalmic lens, the ophthalmic
lens further comprises a plurality of fenestrations, wherein the
plurality of fenestrations is disposed within the inner optic
portion, the peripheral portion, or both the inner optic portion
and the peripheral portion.
[0117] In certain embodiments of an ophthalmic lens, at least some
of the plurality of fenestrations are disposed proximate an
interface between the inner optic portion and the peripheral
portion.
[0118] In certain embodiments of an ophthalmic lens, at least some
of the plurality of fenestrations are configured to pump tear
liquid between the posterior surface of the lens and the epithelium
when the eye blinks.
[0119] In certain embodiments of an ophthalmic lens, at least some
of the plurality of fenestrations are configured to maintain tear
fluid within one or more lenticular volumes between the posterior
surface of the inner optic portion and the cornea.
[0120] In certain embodiments of an ophthalmic lens, the inner
optic portion is primarily configured to correct vision and the
peripheral portion is primarily configured to enhance comfort.
[0121] In certain embodiments of an ophthalmic lens, the posterior
surface of the inner optic portion comprises a thickness of a low
modulus material.
[0122] In certain embodiments of an ophthalmic lens, the ophthalmic
lens is characterized by a sagittal height (SAG) from 3 mm to 5
mm.
[0123] In certain embodiments of an ophthalmic lens, the anterior
surface is characterized by a spherical profile without a
cylindrical component.
[0124] In certain embodiments of an ophthalmic lens, the ophthalmic
lens is configured to center on the optical region of the cornea
following blinking of the eye.
[0125] In certain embodiments, methods for correcting a refractive
error of an eye, the eye having a cornea with a refractive shape
extending across an optical region of the cornea, comprise:
positioning an ophthalmic lens on the eye so that an inner optic
portion of the ophthalmic lens is disposed over the optical region
of the cornea, wherein at least a portion of a posterior surface of
the positioned ophthalmic lens extends adjacent the eye and is
deformed by the eye; and wherein a shape of the posterior surface
diverges from the refractive shape of the cornea so that the
ophthalmic lens mitigates the refractive error.
[0126] In certain methods for correcting refractive error, the
refractive error of the eye comprises astigmatism, spherical
defocus, or a combination thereof; the ophthalmic lens further
comprises a plurality of fenestrations, wherein the plurality of
fenestrations is disposed within the inner optic portion, the
peripheral portion, or both the inner optic portion and the
peripheral portion; the inner portion of the ophthalmic lens is
deformable and a peripheral portion of the ophthalmic lens disposed
outward of the inner optic portion is characterized by a rigidity
lower than a rigidity of the inner portion; and mitigation of the
refractive error when viewing with the eye through the anterior
surface is substantially independent of the shape of the peripheral
portion throughout a range of astigmatic errors of at least about
1.5 D, and is independent of a rotational orientation of the
ophthalmic lens about a viewing axis of the eye.
[0127] In embodiments in which the inner optic portion is
configured to provide a spherical correction, the thickness of the
inner portion will not be uniform, and will be shaped to provide,
for example, a spherical power from about -3.00 D to about +3.00 D,
and in certain embodiments, from about --10.00 D to about +10.00 D.
In such embodiments, the thickness of the inner optic portion can
taper from the center toward the peripheral portion depending on
the spherical power.
[0128] In embodiments, in which correction of spherical power is
not required, the thickness of the inner portion may be
substantially uniform.
[0129] In certain embodiments, ophthalmic lenses are radially
symmetric.
[0130] Certain embodiments of ophthalmic lenses provided by the
present disclosure can be configured to provide one or more
lenticular volumes between at least a portion of the posterior
surface of the inner optic portion and the surface of the
cornea.
[0131] When placed on the cornea, the posterior surface of the
inner optic portion of the ophthalmic lens comprises a shape
diverging from the refractive shape of the cornea and define a
lenticular volume. In certain embodiments, at least a portion of
the peripheral portion may also diverge from the refractive shape
of the cornea and may define a lenticular volume. The peripheral
portion of the lens may diverge from the refractive shape of the
cornea near the interface of the inner optic portion and the
peripheral portion. Depending upon the shape of the cornea, one or
more lenticular volumes may be formed
[0132] A lenticular volume defined by the peripheral portion of a
lens may be fluidly connected to a lenticular volume defined by the
inner portion and may facilitate exchange of tear fluid within one
or more lenticular volumes. Tear exchange within a lenticular
volume and to and from a lenticular volume may be facilitated by
fenestrations through the ophthalmic lens. Such fenestrations may
serve to pump tear fluid to and from a lenticular volume during
blinking of the eye.
[0133] In certain embodiments, the inner optic portion comprises a
shape configured to provide a spherical power to correct refractive
error, and in certain embodiments, comprises a shape configured to
correct non-spherical refractive error.
[0134] In certain embodiments, the anterior surface of the inner
optic portion is characterized by a substantially spherical
shape.
[0135] In certain embodiments, the posterior surface of the inner
optic portion may be characterized by a substantially spherical
shape.
[0136] In other embodiments, the posterior surface of the inner
optic portion may be characterized by a non-spherical shape such
as, for example, a toric shape. In embodiments in which the
posterior surface is characterized by a toric shape, the shape can
be configured such that the toric shape of inner optic portion
aligns with an astigmatic axis of the cornea. The toric shape can
be from 0.75 D to 1.25 D. The toric shape can reduce the lenticular
volume compared to a spherical shape. The reduced lenticular volume
results in less lens flexure of the contact lens during blinking.
The tonic shape of the posterior surface can induce a certain
amount of astigmatism.
[0137] The induced astigmatism by the toric shape of the posterior
surface can be compensated by having an anterior surface with a
toric shape. The amount of toricity of the posterior surface may be
sufficient to correct any astigmatism induced by the toricity of
the anterior surface of the lens. The anterior surface may also
include a shape for spherical correction.
[0138] In certain embodiments, an ophthalmic lens will have a
spherical power effect bitoric design that is independent of lens
orientation.
[0139] In certain embodiments, the inner optic portion comprises a
single material throughout the thickness.
[0140] In certain embodiments, the inner optic portion comprises
more than one material, with different materials disposed in
different axial portions of the inner optic portion. For example,
the inner optic portion may comprise a first portion disposed
toward and/or forming the anterior surface of the inner optic
portion, toward and/or forming the posterior surface of the inner
optic portion, or toward the center of the inner optic portion. In
such embodiments, the first portion comprises a material
characterized by a modulus higher than that of a material forming
the peripheral portion. The first portion comprises a material and
is characterized by a thickness sufficient to provide correction of
refractive error.
[0141] By virtue of being characterized by at least different
moduli, the material forming the first portion is not structurally
the same as the anterior material and/or the posterior material,
although the materials may be based on similar chemistries and/or
materials. In certain embodiments, the anterior material can be the
same as the posterior material and in certain embodiments the
anterior material can be different than the posterior material. In
certain embodiments, the anterior material, the posterior material,
and the peripheral material are the same and the anterior material
and the posterior material extend from the inner optic portion to
the peripheral portion.
[0142] In certain embodiments, one or more surfaces of the first
portion may be treated to enhance the mechanical integrity and/or
adhesion of the interface with the first portion and the anterior
portion and/or the posterior portion.
[0143] In certain embodiments, the inner optic portion, the
peripheral portion, or both the inner optic portion and the
peripheral portion may comprise one or more coatings on the
anterior surface, the posterior surface, or both the anterior
surface and the posterior surface.
[0144] The one or more coatings may be selected, for example, to
improve comfort, to facilitate tear flow, and/or to modify the
hydrophilicity/hydrophobicity of the lens or portion of the lens.
The one or more coatings may be the same in both the inner optic
portion and in the peripheral portion or may be different in
different portions of the lens.
[0145] In certain embodiments, the materials forming the inner
optic portion, the peripheral portion, or both the inner optic
portion and the peripheral portion are non-hydrous. A non-hydrous
material refers to a material characterized by a water content less
than about 10 wt %, less than about 5 wt %, and in certain
embodiments, less than about 1 wt % in its fully hydrated
state.
[0146] A material may be intrinsically non-hydrous or may be
rendered functionally non-hydrous by situating or encapsulating a
material between non-hydrous materials and/or by a coating with a
non-hydrous and/or hydrophobic material. For example, a hydrophobic
coating such as a hydrocarbon or fluorocarbon coating may be used
to prevent hydration of a hydrous material.
[0147] The material forming the inner optic portion and the
peripheral portion may be characterized by the same or by a
different water content.
[0148] In embodiments in which the inner optic portion comprises
more than one axial portion, the first or optical portion may
comprise a non-hydrous material and the anterior portion and/or
posterior portions may comprise a hydrous material, such as a
hydrogel.
[0149] The inner optic portion comprises an inner material
characterized by an inner modulus, and the peripheral portion
comprises a peripheral material characterized by a peripheral
modulus, wherein the inner modulus is greater than the outer
modulus.
[0150] The materials forming the inner optic portion and the
peripheral portion may be polymers, copolymers, homopolymers, graft
polymers, or graft copolymers. The materials may comprise a
combination of more than one different type of materials. In
certain embodiments, the materials may be hydrogels. A hydrogel
refers to a cross-linked polymeric material, which is not
water-soluble and contains at least 10 wt % water within the
polymer matrix when fully hydrated. In certain embodiments, a
material forming the inner optic portion and/or the peripheral
portion is not a hydrogel and contains less than 10 wt % water.
[0151] Examples of suitable materials for forming the inner optic
portion include, for example, silicones, fluorosilicones,
polyurethanes, polyether block amides, polycarbonates, polymethyl
methacrylates, polystyrenes, and acrylonitrile butadiene styrene,
polymers of methacrylate and acrylate esters of various alcohols,
including aliphatic, aromatic, siloxane-containing,
fluorocarbon-containing alcohols, and combinations of any of the
foregoing. Such materials for the inner optic portion are
characterized by a modulus from about 100 MPa to about 3000
MPa.
[0152] Examples of suitable materials for forming the peripheral
portion include, for example, silicone, silicone hydrogels, and
hydrogels of optically clear materials such as those listed for the
inner portion modified with a suitable hydrophilic material such as
polyhydroxyethylmethacrylate hydrogels, polyvinylpyrrolidone
hydrogels, polyvinylalcohol hydrogels, silicone hydrogels.
[0153] Ophthalmic lenses provided by the present disclosure may be
manufactured using any suitable contact lens manufacturing
technology including, for example, cast molding, injection molding,
insert molding, transfer molding, thermoforming, vacuum forming, or
a combination of any of the foregoing.
[0154] In certain embodiments, the inner optic portion comprising a
higher modulus material may be thermoplastic and can be fabricated
by injection molding. The inner optic portion may then be inserted
into a mold cavity and the peripheral portion formed to retain the
inner optic portion. This may be accomplished, for example, using
insert molding or cast molding technologies. In certain
embodiments, the material forming the peripheral portion also
covers the anterior surface, the posterior surface, or both the
anterior surface and the posterior surface of the inner portion.
Cast molding resins may be, for example, heat cured or radiation
cured such as UV cured.
[0155] Scaffolds provided by the present disclosure may be
fabricated using any suitable technology. The technology may be
selected as appropriate for the material or materials used to form
the scaffold.
[0156] For example, scaffolds may be fabricated using injection
molding, compression molding, thermoforming, a lathe, or cast
molding.
[0157] The material forming the scaffold may be a thermoplastic or
may be a curable liquid. A curable material may be curable by heat
or by radiation.
[0158] The openings in the scaffold may be formed at the time the
scaffold is fabricated or may be machined after the scaffold is
formed. The openings may be incorporated into the mold design. The
openings may also be machined after the part is formed using, for
example, laser machining, die cutting, or other suitable
method.
[0159] To fabricate a contact lens, the scaffold may be first
positioned in a mold cavity and then a second material formed
around the scaffold by injection molding, compression molding, cast
molding or other suitable molding technology. The second material
can form the anterior and posterior surface of the inner optic
portion, fill the openings in the scaffold, and also form the
peripheral portion of the contact lens.
[0160] In certain embodiments the low modulus material may be a
thermoplastic and the contact lens formed by insert molding the
scaffold.
[0161] For high volume manufacturing it may be desirable to
position the scaffold in a cast mold, fill the mold with a liquid
low modulus material, and cure the low modulus material using
actinic radiation such as ultraviolet radiation.
[0162] While certain 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.
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