U.S. patent application number 11/844087 was filed with the patent office on 2008-02-21 for accommodating intraocular lens system having spherical aberration compensation and method.
Invention is credited to Denise Horrilleno Burns, Victor Esch, John A. Scholl, Terah Whiting Smiley, David John Smith.
Application Number | 20080046074 11/844087 |
Document ID | / |
Family ID | 39591158 |
Filed Date | 2008-02-21 |
United States Patent
Application |
20080046074 |
Kind Code |
A1 |
Smith; David John ; et
al. |
February 21, 2008 |
Accommodating Intraocular Lens System Having Spherical Aberration
Compensation and Method
Abstract
An accommodating intraocular lens includes an optic portion, a
haptic portion. The optic portion of the lens includes an actuator
that deflects a lens element to alter the optical power of the lens
responsive to forces applied to the haptic portion of the lens by
contraction of the ciliary muscles and a secondary deflection
mechanism. Movement of the lens element by the actuator causes the
lens element to deform and the secondary deflection mechanism
causes the lens to further deform.
Inventors: |
Smith; David John;
(Highland, CA) ; Smiley; Terah Whiting; (San
Francisco, CA) ; Scholl; John A.; (San Ramon, CA)
; Burns; Denise Horrilleno; (Sunnyvale, CA) ;
Esch; Victor; (Albuquerque, NM) |
Correspondence
Address: |
SHAYGLENN LLP
2755 CAMPUS DRIVE
SUITE 210
SAN MATEO
CA
94403
US
|
Family ID: |
39591158 |
Appl. No.: |
11/844087 |
Filed: |
August 23, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11646913 |
Dec 27, 2006 |
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11844087 |
Aug 23, 2007 |
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10971598 |
Oct 22, 2004 |
7261737 |
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11646913 |
Dec 27, 2006 |
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10734514 |
Dec 12, 2003 |
7122053 |
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10971598 |
Oct 22, 2004 |
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60433046 |
Dec 12, 2002 |
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Current U.S.
Class: |
623/6.13 |
Current CPC
Class: |
A61F 2/1635 20130101;
A61F 2/1637 20130101; A61F 2002/1681 20130101 |
Class at
Publication: |
623/006.13 |
International
Class: |
A61F 2/16 20060101
A61F002/16 |
Claims
1. An intraocular lens configured for implantation in a capsular
sac following extraction of a natural lens, the intraocular lens
accommodating in response to movement of the capsular sac, the
intraocular lens comprising: an optic portion including a lens
element, an intermediate layer and an actuator, the actuator
disposed in contact with the lens element; a haptic having an
interior volume coupled in fluid communication with the actuator; a
fluid disposed in the actuator and the interior volume of the
haptic; and a secondary deflection mechanism coupled to the lens
element, wherein the lens element is configured to be deformed by
movement of the actuator in response to movement of the first fluid
between the haptic and the actuator, and wherein the secondary
deflection mechanism is configured to further deform the lens
element in response to deformation of the lens element by the
actuator.
2. The intraocular lens of claim 1 wherein the secondary deflection
mechanism is a portion of the lens element having a reduced
thickness.
3. The intraocular lens of claim 1 wherein the secondary deflection
mechanism is a flexible coupling between the lens element and the
intermediate layer.
4. The intraocular lens of claim 1 wherein the secondary deflection
mechanism is a fluid-mediated actuator comprising a sealed cavity
between the lens element and the intermediate later that is filled
with a second fluid, and wherein deformation of the lens element
and movement of the actuator redistributes the second fluid within
the sealed cavity which further deforms the lens element.
5. The intraocular lens of claim 4 wherein the first fluid and the
second fluid have approximately the same refractive index.
6. The intraocular lens of claim 4 wherein the lens element and the
actuator are configured such that the volume of a peripheral
portion of the sealed cavity decreases and the volume of a central
portion of the sealed cavity increases when the first fluid is
transferred from the haptic to the actuator.
7. The intraocular lens of claim 1 further comprising a backstop
coupled to at least a portion of the haptic.
8. The intraocular lens of claim 1 further comprising a support
member that extends further radially outward than the haptic.
9. The intraocular lens of claim 1 wherein the actuator includes a
rolling undulation.
10. The intraocular lens of claim 1 wherein the actuator includes a
bellows.
11. The intraocular lens of claim 1 wherein the intermediate layer
and the actuator are monolithic.
12. The intraocular lens of claim 1 wherein the intermediate layer
and the actuator are separate components coupled together.
13. The intraocular lens of claim 4 wherein the lens element and
the intermediate layer are sealed such that relative motion
adjacent the seal is permitted.
14. The intraocular lens of claim 1 wherein the lens element is
deformed to an aspheric configuration by the actuator and secondary
deflection mechanism.
15. An intraocular lens configured for implantation in a capsule
following extraction of a natural lens, the intraocular lens
accommodating in response to shape changes of the patient's lens
capsule, the intraocular lens comprising: an optic portion
including a lens element, an actuator and a sealed fluid cavity
adjacent at least a portion of the lens element; a haptic having an
interior volume coupled in fluid communication with the actuator,
and a capsule wall contacting portion; a first fluid disposed in
the actuator and the interior volume of the haptic; and a second
fluid disposed in the sealed fluid cavity, wherein the actuator is
coupled with the lens element such that shape changes of the
patient's lens capsule displaces fluid between the interior volume
of the haptic and the actuator to change a deflection of the lens
element, and wherein deflection of the lens element causes the
second fluid to redistribute within the sealed fluid cavity to
alter the deflection of the lens element.
16. The intraocular lens of claim 15 further comprising a backstop
coupled to at least a portion of the haptic.
17. The intraocular lens of claim 15 further comprising a support
member that extends further radially outward than the haptic.
18. The intraocular lens of claim 17 wherein the support member is
a wire that circumscribes and is radially spaced from the
haptic.
19. The intraocular lens of claim 17 wherein the support member is
a tab that extends radially outward from a portion of the
haptic.
20. The intraocular lens of claim 15 wherein the support member is
integrated into the haptic.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of pending U.S.
application Ser. No. 11/646,913, filed Dec. 27, 2006; which
application is a continuation-in-part of U.S. application Ser. No.
10/971,598, filed Oct. 22, 2004; which is a continuation-in-part of
U.S. application Ser. No. 10/734,514, filed Dec. 12, 2003, and
claims the benefit of priority from U.S. Provisional Application
No. 60/433,046, filed Dec. 12, 2002, the disclosures of which are
hereby incorporated by reference in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to intraocular lenses ("IOLs")
having optical parameters that are changeable in-situ. More
particularly, the invention has application in IOLs for in-capsule
implantation for cataract patients or presbyopic patients, wherein
movement of the lens capsule applies forces to a circumferentially
supported haptic to more efficiently induce transfer of fluid media
within the interior of the IOL to alter an optical power of the
lens.
BACKGROUND OF THE INVENTION
[0003] Cataracts are a major cause of blindness in the world and
the most prevalent ocular disease. Visual disability from cataracts
accounts for more than 8 million physician office visits per year.
When the disability from cataracts affects or alters an
individual's activities of daily living, surgical lens removal with
intraocular lens (IOL) implantation is the preferred method of
treating the functional limitations. In the United States, about
2.5 million cataract surgical procedures are performed annually,
making it the most common surgery for Americans over the age of 65.
About 97 percent of cataract surgery patients receive intraocular
lens implants, with the annual costs for cataract surgery and
associated care in the United States being upwards of $4
billion.
[0004] A cataract is any opacity of a patient's lens, whether it is
a localized opacity or a diffuse general loss of transparency. To
be clinically significant, however, the cataract must cause a
significant reduction in visual acuity or a functional impairment.
A cataract occurs as a result of aging or secondary to hereditary
factors, trauma, inflammation, metabolic or nutritional disorders,
or radiation. Age-related cataract conditions are the most
common.
[0005] In treating a cataract, the surgeon removes the crystalline
lens matrix from the lens capsule and replaces it with an
intraocular lens ("IOL") implant. The typical IOL provides a
selected focal length that allows the patient to have fairly good
distance vision. Since the lens can no longer accommodate, however,
the patient typically needs glasses for reading.
[0006] More specifically, the imaging properties of the human eye
are facilitated by several optical interfaces. A healthy youthful
human eye has a total power of approximately 59 diopters, with the
anterior surface of the cornea (e.g. the exterior surface,
including the tear layer) providing about 48 diopters of power,
while the posterior surface provides about -4 diopters. The
crystalline lens, which is situated posterior of the pupil in a
transparent elastic capsule, also referred to herein as "capsular
sac," supported by the ciliary muscles via zonules, provides about
15 diopters of power, and also performs the critical function of
focusing images upon the retina. This focusing ability, referred to
as "accommodation," enables imaging of objects at various
distances.
[0007] The power of the lens in a youthful eye can be adjusted from
15 diopters to about 29 diopters by adjusting the shape of the lens
from a moderately convex shape to a highly convex shape. The
mechanism generally accepted to cause this adjustment is that
ciliary muscles supporting the capsule (and the lens contained
therein) move between a relaxed state (corresponding to the
moderately convex shape) and a contracted state (corresponding to
the highly convex shape). Because the lens itself is composed of
viscous, gelatinous transparent fibers, arranged in an "onion-like"
layered structure, forces applied to the capsule by the ciliary
muscles via the zonules cause the lens to change shape.
[0008] Isolated from the eye, the relaxed capsule and lens take on
a more spherical shape. Within the eye, however, the capsule is
connected around its circumference by approximately 70 tiny
ligament fibers to the ciliary muscles, which in turn are attached
to an inner surface of the eyeball. The ciliary muscles that
support the lens and capsule therefore are believed to act in a
sphincter-muscular mode. Accordingly, when the ciliary muscles are
relaxed, the capsule and lens are pulled about the circumference to
a larger diameter, thereby flattening the lens, whereas when the
ciliary muscles are contracted the lens and capsule relax somewhat
and assume a smaller diameter that approaches a more spherical
shape.
[0009] As noted above, the youthful eye has approximately 14
diopters of accommodation. As a person ages, the lens hardens and
becomes less elastic, so that by about age 45-50, accommodation is
reduced to about 2 diopters. At a later age the lens may be
considered to be non-accommodating, a condition known as
"presbyopia". Because the imaging distance is fixed, presbyopia
typically entails the need for bifocals to facilitate near and far
vision.
[0010] Apart from age-related loss of accommodation ability, such
loss is innate to the placement of IOLs for the treatment of
cataracts. IOLs are generally single element lenses made from a
suitable polymer material, such as acrylics or silicones. After
placement, accommodation is no longer possible, although this
ability is typically already lost for persons receiving an IOL.
There is significant need to provide for accommodation in IOL
products so that IOL recipients will have accommodating
ability.
[0011] Although previously known workers in the field of
accommodating IOLs have made some progress, the relative complexity
of the methods and apparatus developed to date have prevented
widespread commercialization of such devices. Previously known
devices have proved too complex to be practical to construct or
have achieved only limited success, due to the inability to provide
accommodation of more than 1-2 diopters.
[0012] U.S. Pat. No. 5,443,506 to Garabet describes an
accommodating fluid-filled lens wherein electrical potentials
generated by contraction of the ciliary muscles cause changes in
the index of refraction of fluid carried within a central optic
portion. U.S. Pat. No. 4,816,031 to Pfoff discloses an IOL with a
hard poly methyl methacrylate (PMMA) lens separated by a single
chamber from a flexible thin lens layer that uses microfluid pumps
to vary a volume of fluid between the PMMA lens portion and the
thin layer portion and provide accommodation. U.S. Pat. No.
4,932,966 to Christie et al. discloses an intraocular lens
comprising a thin flexible layer sealed along its periphery to a
support layer, wherein forces applied to fluid reservoirs in the
haptics vary a volume of fluid between the layers to provide
accommodation.
[0013] Although fluid-actuated mechanisms such as described in the
aforementioned patents have been investigated, currently available
accommodating lenses include the Crystalens developed by Eyeonics,
Inc. (formerly C&C Vision, Inc.) of Aliso Viejo, Calif.
According to Eyeonics, redistribution of the ciliary mass upon
constriction causes increased vitreous pressure resulting in
forward movement of the lens.
[0014] Co-pending, commonly assigned U.S. Patent Application
Publication No. 2005/0119740 to Esch et al., which is incorporated
by reference herein in its entirety, describes an intraocular lens
in which forces applied by the lens capsule to a haptic portion of
the lens to induce fluid transfer to and from an actuator disposed
in contact with a dynamic surface of the lens.
[0015] Another disadvantage of previously known devices is that
they oftentimes create spherical aberrations. As is well known in
the art, lenses composed of elements having spherical surfaces are
easy to manufacture but are not ideal for creating a sharp image
because light passing through the elements does not focus on a
single focal point. In particular, light that passes through a
positive optical element close to the optical axis generally
converges at a focal point that is further from the lens than a
focal point of light passing through the peripheral portion of the
lens, thereby creating under corrected spherical aberration. As a
result of spherical aberration in an intraocular lens, all of the
light passing through the lens does not focus on the retina
resulting in an image that may be blurred and may have softened
contrast.
[0016] Various devices have been used in optical systems to reduce
the effect of spherical aberration. For example, an aperture may be
used that limits the ability of light to pass through the
peripheral portion of the lens. As a result, the light contributing
to the aberration is prevented from passing through the lens. Such
a device provides an obvious disadvantage that the amount of light
allowed to pass through the lens is reduced. Another way to reduce
the effect of spherical aberration is to combine two lenses, one
convex and one concave. A still further method of reducing the
effects of spherical aberration is to use an aspherical lens.
However, such combined lenses and lenses having aspherical profiles
are significantly more expensive to produce. In addition, combining
lenses requires additional space to house the multiple lenses.
[0017] While the lens described in the foregoing Esch application
is expected to provide significant benefits over previously-known
accommodating lens designs, it would be desirable to provide
methods and apparatus for further enhancing conversion of lens
capsule movements into hydraulic forces, so as to improve
modulation of the lens actuator and dynamic surface.
[0018] It also would be desirable to provide methods and apparatus
to enhance the efficiency with which loads arising due to natural
accommodating muscular action are converted to hydraulic
forces.
[0019] It also would be desirable to provide methods and apparatus
that reduce spherical aberration while maximizing the useful
surface area of an accommodating lens design.
SUMMARY OF THE INVENTION
[0020] In view of the foregoing, it is an object of the present
invention to provide apparatus and methods that restore appropriate
optical focusing power action to the human eye.
[0021] It is a further object of this invention to provide methods
and apparatus wherein a dynamic lens surface may be hydraulically
manipulated responsive to movement of the ciliary muscles and lens
capsule.
[0022] It also is an object of the present invention to provide
methods and apparatus for further enhancing conversion of lens
capsule movements into hydraulic forces, so as to improve
modulation of the lens actuator and dynamic surface.
[0023] It is another object of this invention to provide methods
and apparatus to enhance the efficiency with which loads arising
due to natural accommodating muscular action are converted to
hydraulic forces.
[0024] It is another object of this invention to provide methods
and apparatus for reducing spherical aberration in an accommodating
intraocular lens device.
[0025] These and other objects of the present invention are
accomplished by providing an intraocular lens responsive to forces
communicated from the ciliary muscles through the zonules to the
capsular bag to operate one or more actuators disposed within the
IOL. The actuator is coupled to a dynamic surface of the IOL to
deflect the dynamic surface, e.g., from a moderately convex to a
highly convex shape, responsive to operation of the one or more
actuators. In accordance with the principles of the present
invention, the IOL includes at least one secondary deflection
mechanism that is configured to further alter the curvature of the
dynamic surface to correct for spherical aberration. The secondary
deflection mechanism may be alterations of the lens such as varying
thickness or inflection points, selection of the boundary condition
of the lens, and secondary fluid-mediated actuators.
[0026] In an embodiment, the secondary deflection mechanism is a
fluid-mediated actuator coupled to a fluid column disposed in at
least one haptic of the IOL and a sealed fluid cavity filled with
shaping fluid that is adjacent to the dynamic surface. Forces
applied to the haptic by the capsular bag, responsive to movement
of the ciliary muscles, cause the transfer of fluid between the
fluid column and the actuator, which in turn deflects a dynamic
surface of the lens.
[0027] Deflection of the dynamic surface causes the shaping fluid
in the sealed fluid cavity to redistribute which, in turn, alters
the shape of the dynamic surface so that it is aspherical. By
making the dynamic surface aspherical the total amount of travel
required by the actuator may be reduced from approximately 300
microns for non-aspheric lenses to 200 microns. As a result, a more
efficient IOL may be produced that requires less influence from the
lens capsule.
[0028] In a preferred embodiment, the intraocular lens comprises an
optic portion including a fluid cavity containing a fixed volume of
shaping fluid and a haptic (or non-optic) portion. The optic
portion comprises a light transmissive substrate defining one or
more fluid channels, at least one actuator coupled in fluid
communication with the fluid channels, and anterior and posterior
lens elements. At least one of the anterior and posterior lens
elements includes a dynamic surface that is operatively coupled to
the actuator to cause deflection of the dynamic surface. The other
of the anterior or posterior lens elements may be coupled to the
substrate or integrally formed therewith.
[0029] The haptic portion is disposed at the periphery of the optic
portion and comprises one or more haptics that extend outward from
the optic portion, each haptic including a fluid channel coupled in
fluid communication with a fluid channel in the optic portion. In
accordance with one aspect of the present invention, the haptics
have a cross-sectional configuration selected so that the internal
volume of the haptic is small in an accommodated state. The
accommodated state of the haptic is selected to correspond to the
accommodated state of the eye, when the ciliary muscles are
contracted and anterior/posterior compressive forces applied by the
capsular bag to the haptics are reduced.
[0030] When the ciliary muscles relax, the zonules pull the
capsular sac taut and apply forces to the anterior and posterior
faces of the haptic. The forces applied by the capsular sac cause
the cross-sectional area of the haptic to increase thereby
increasing the internal volume of the haptic. This action in turn
causes fluid to be withdrawn from the actuator disposed in the
optic portion, so that the dynamic surface of the IOL transitions
from an accommodated state to an unaccommodated state. The fixed
volume of shaping fluid in the sealed fluid cavity is redistributed
in the cavity by movement of the dynamic surface and that
redistribution causes the shape of the dynamic surface to be
altered.
[0031] The actuator used in the optic portion of the IOL may be
centrally located within the optic portion that, when filled with
fluid, biases the dynamic surface of the IOL to the accommodated
state. When the ciliary muscles are contracted, the zonules and
capsular bag are less taut, and the haptics are unstressed.
Relaxation of the ciliary muscle causes the zonules to transition
the capsule to less convex shape, which applies compressive forces
to the haptic, thereby withdrawing fluid from the actuator and
causing the lens to transition to the unaccommodated state.
Alternatively, the actuator may comprise structures disposed at the
periphery of the optic portion, so as to further minimize
refractive effects and optical aberrations in the optic
portion.
[0032] Methods of making and using the lens of the present
invention also are provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Further features of the invention, its nature and various
advantages will be more apparent from the accompanying drawings and
the following detailed description of the preferred embodiments, in
which:
[0034] FIG. 1 is a sectional side view of a human eye;
[0035] FIGS. 2A and 2B are, respectively, sectional side views of
the lens and supporting structures of FIG. 1 illustrating relaxed
and contracted states of the ciliary muscles;
[0036] FIG. 3 is another sectional side view of a human eye
illustrating light passing through a spherical lens in the lens
capsule;
[0037] FIGS. 4A-4C are, respectively, a perspective, exploded
perspective and plan view of an exemplary intraocular lens which
may be modified to implement the structure and methods of the
present invention;
[0038] FIG. 5 is a cross-sectional view of a haptic of the
intraocular lens of FIG. 4;
[0039] FIG. 6 is a cross-sectional view of the assembled
intraocular lens of FIG. 4;
[0040] FIGS. 7A, 7B and 7C are, respectively, cross-sectional views
of an intraocular lens optic portion in unaccommodated (FIGS. 7A
and 7B), and accommodated configurations (FIG. 7C);
[0041] FIGS. 8A and 8B are, respectively, a perspective view and a
cross-sectional view of an illustrative embodiment of the
intraocular lens of the present invention;
[0042] FIGS. 9A and 9B are, respectively, a perspective view and a
cross-sectional view of an alternative embodiment of the
intraocular lens of the present invention;
[0043] FIGS. 10A and 10B are, respectively, a perspective view and
a cross-sectional view of an alternative embodiment of the
intraocular lens of the present invention;
[0044] FIGS. 11A and 11B are, respectively, a perspective view and
a cross-sectional view of an alternative embodiment of the
intraocular lens of the present invention; and
[0045] FIG. 12 is a perspective view of an alternative embodiment
of the intraocular lens of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0046] In accordance with the principles of the present invention,
an intraocular lens is provided having a haptic portion and a
light-transmissive optic portion. The optic portion contains one or
more fluid-mediated actuators arranged to apply a deflecting force
on a dynamic surface of the lens to provide accommodation. As used
herein, the lens is fully "accommodated" when it assumes its most
highly convex shape, and fully "unaccommodated" when it assumes its
most flattened, least convex state. The lens of the present
invention is capable of dynamically assuming any desired degree of
accommodation between the fully accommodated state and fully
unaccommodated state responsive to movement of the ciliary muscles
and lens capsule.
[0047] Furthermore, in accordance with the principles of the
present invention the optic portion contains one or more secondary
deflection mechanism that alters the curvature of the lens. For
example, the secondary deflection mechanism may be sealed fluid
cavities that are filled with a constant volume of shaping fluid
that is redistributed when the lens is actuated between the
accommodated and unaccommodated states. As will be discussed in
further detail below, when a fluid-mediated actuator applies a
deflecting force on a portion of the dynamic surface it causes a
portion of a sealed fluid cavity to change in volume. However,
because the volume of fluid is fixed, the change in volume in one
portion of the cavity causes a complimentary change in volume of
another portion, whereby one portion of the dynamic surface becomes
more convex at a different rate than another portion. The secondary
deflection mechanism also may be integrated into the lens, such as
varying thickness or inflection points or areas. As a further
alternative, the secondary deflection mechanism may be a boundary
condition, i.e., characteristics of the connection of the lens to
the remainder of the optic portion around the circumference. As a
result of the one or more secondary deflection mechanism, the
dynamic surface may be deflected into an aspheric profile, which
may be used to correct spherical aberration.
[0048] Referring to FIGS. 1 and 2, the structure and operation of a
human eye are first described as context for the present invention.
Eye 10 includes cornea 11, iris 12, ciliary muscles 13, ligament
fibers or zonules 14, capsule 15, lens 16 and retina 17. Natural
lens 16 is composed of viscous, gelatinous transparent fibers,
arranged in an "onion-like" layered structure, and is disposed in
transparent elastic capsule 15. Capsule 15 is joined by zonules 14
around its circumference to ciliary muscles 13, which are in turn
attached to the inner surface of eye 10. Vitreous 18 is a highly
viscous, transparent fluid that fills the center of eye 10.
[0049] Isolated from the eye, the relaxed capsule and lens take on
a convex shape. However, when suspended within the eye by zonules
14, capsule 15 moves between a moderately convex shape (when the
ciliary muscles are relaxed) and a highly convex shape (when the
ciliary muscles are contracted). As depicted in FIG. 2A, when
ciliary muscles 13 relax, capsule 15 and lens 16 are pulled about
the circumference, thereby flattening the lens. As depicted in FIG.
2B, when ciliary muscles 13 contract, capsule 15 and lens 16 relax
and become thicker. This allows the lens and capsule to assume a
more convex shape, thus increasing the diopter power of the
lens.
[0050] Additionally, various natural mechanisms affect the design
requirements of the present invention. For example, during
accommodation the pupil naturally stops down (i.e., reduces in
diameter) which reduces the area of the natural lens that transmits
light. In addition, the eye will experience the Stiles-Crawford
Effect which also reduces the effective area of the natural lens.
In particular, the brightness of light rays incident on cones in
the eye is dependent on the angle at which those rays are incident
on the cones. In particular, light rays that strike the cones
perpendicular to their surface appear brighter than those that do
not. As a result, the light rays passing through the periphery of
the lens are less significant for proper vision.
[0051] Accommodating lenses that are currently commercially
available, such as the Crystalens device developed by Eyeonics,
Inc., Aliso Viejo, Calif., typically involve converting movements
of the ciliary muscle into anterior and posterior translation of an
optic portion of the IOL relative to the retina. Such devices do
not employ the natural accommodation mechanisms described above
with respect to FIGS. 1-2, but instead rely directly on changes in
vitreous pressure to translate the lens.
[0052] Referring now to FIG. 3, a simplified schematic is provided
of the spherical aberration effects of implanting spherical lens 19
within capsule 15 thereby introducing spherical aberrations. In
particular, light rays L passing through a central portion of
spherical lens 19, i.e., near the optical axis, converge at
location A on retina 17. However, light rays L passing through the
peripheral portion of spherical lens 19 converge at location B
which is spaced from location A and retina 17. Because location B
is spaced from retina 17, when those light rays reach retina 17
they are dispersed. Although only two focal points are illustrated
in FIG. 3, it should be appreciated that light rays passing through
lens 19 will focus at many different focal points along the optical
axis of the lens and the distance of any particular focal point
from retina 17 depends on the radial location on lens through which
the light rays pass.
[0053] Referring now to FIGS. 4-6, an exemplary embodiment of an
intraocular lens suitable for implementing the structure of the
present invention is described, such as is described in the
commonly assigned U.S. Patent Application No. 2005/0119740 to Esch
et al., which is incorporated herein by reference. For completeness
of disclosure, details of the IOL described in that application are
provided below.
[0054] IOL 20 comprises optic portion 21 and haptic portion 22.
Optic portion 21 is constructed of light transmissive materials,
while haptic portion 22 is disposed at the periphery of the optic
portion and does not participate in focusing light on the retina of
the eye.
[0055] Optic portion 21 comprises anterior lens element 23
including actuator 24 (see FIG. 6), intermediate layer 25 and
posterior lens element 27, also referred to herein as "substrate,"
all made of light-transmissive materials, such as silicone or
acrylic polymers or other biocompatible materials as are known in
the art of intraocular lenses. Illustratively, actuator 24
comprises a bellows structure that is integrally formed with
anterior lens element 23. It will be appreciated that actuator 24
may alternatively be integrally formed with intermediate layer 25,
if desired. Optic portion 21 is illustratively described as
comprising three layers, although it will be apparent that other
arrangements may be employed.
[0056] Anterior lens element 23, actuator 24 and intermediate layer
25 are spaced from each other and lens element 23 and intermediate
layer 25 are sealably coupled at their circumferences to define
cavity 34 therebetween. Cavity 34 is filled with a fixed volume of
shaping fluid. The shaping fluid is light-transmissive fluid,
preferably silicone or acrylic oil or another suitable
biocompatible fluid, and is selected to have a refractive index
that matches the materials of anterior lens element 23, actuator
24, intermediate layer 25 and posterior lens element 27.
Furthermore, the viscosity of shaping fluid is selected so that
shaping fluid may be easily distributed within cavity 34 in
response to relative motion between anterior lens element 23,
actuator 24 and intermediate layer 25.
[0057] Haptic portion 22 illustratively comprises haptics 28 and 29
that extend from substrate 26. Each of haptics 28 and 29 includes
an interior volume 30 that communicates with channel 31 in
substrate 26. Actuator 24 is disposed in well 32 formed in
intermediate layer 25 and substrate 27, so that a lower end of the
actuator seats within well 32. Haptics 28 and 29 may include
resilient support members 33 (see FIGS. 5 and 6) that urge haptics
28, 29 radially outward to ensure that haptics 28, 29 seat against
the capsular equator and ensure that optic portion 21 remains
centered in capsule 15. It should be appreciated that support
members 33 need not form a portion of the structure of haptics 28,
29, but instead may be separate components that primarily ensure
that optic portion 21 remains centered, as will be described in
further detail with reference to additional embodiments below.
[0058] Although channel 31 and well 32 are depicted in FIG. 6
having their side walls disposed parallel to the optical axis of
the lens, it is expected that all such surfaces may be arranged
obliquely relative to the optical axis of IOL 20. Such an
arrangement is expected to reduce the potential to create spurious
reflections in light passing along the optical axis of the IOL. It
should be understood that such arrangements may be beneficially
employed throughout the IOLs described in this specification.
[0059] As depicted in FIG. 5, each of haptics 28, 29 has an
undeformed state and may be transitioned to a deformed state (shown
in dotted line in FIG. 5) by application of compressive forces
(shown by arrows C) to the anterior and posterior surfaces of
haptic 28, 29. Haptics 28 and 29 are configured so that the
interior volumes of the haptics increase as the haptics deform from
the undeformed, unstressed state to the deformed state. The
undeformed, unstressed state depicted by the solid lines in FIG. 5
corresponds to a fully-contracted state of the ciliary muscles, as
described herein below.
[0060] Actuator 24 is disposed in well 31 of intermediate layer 25
and substrate 27, and preferably comprises a sturdy elastomeric
material. Intermediate layer 25 and actuator isolate fluid in
channel 31, well 32 and the interior of actuator 24 from the
shaping fluid disposed in cavity 34. The fluid disposed within
channel 31, well 32 and actuator 24, preferably comprises silicone
or acrylic oil or another suitable biocompatible fluid, and is
selected to have a refractive index that matches the materials of
anterior lens element 23, actuator 24, intermediate layer 25 and
posterior lens element 27.
[0061] Illustratively, actuator 24 comprises a bellows structure
integrally formed with anterior lens element 23, and is configured
to deflect anterior lens element 23 responsive to fluid pressure
applied within the bellows by haptics 28, 29. Alternatively,
actuator 24 may be fabricated as a separate component and glued or
otherwise bonded to anterior lens element 23 and intermediate layer
25.
[0062] Deflection of the anterior lens element resulting from
movement of actuator 24 causes the anterior lens element to
transition between an accommodated state, in which the lens surface
is more convex, to an unaccommodated state, in which the lens
surface is less convex. As will of course be understood, optic
portion could instead be arranged so that actuator 24 deflects
posterior lens element 27. Still further, the actuator may be
configured to induce a major deflection of one lens element and a
minor deflection of the other lens element; the arrangement
depicted in FIG. 4 is intended to be illustrative only.
[0063] The inner surface and thickness of anterior element 23
(relative to the optical axis of the lens) are selected so that the
outer surface of anterior lens element 23 retains an optically
corrective shape throughout the entire range of motion of actuator
24, e.g., for accommodations 0-10 diopters. It should of course be
understood that the inner surface and thickness of anterior element
23 may be selected to provide an aspherical outer surface in
combination with the deforming characteristics of the shaping fluid
within cavity 34 of the present invention, as required for a
desired degree of optical correction.
[0064] While IOL 20 includes a single actuator 24 located at the
center of optic portion 21, the IOL alternatively may include an
array of actuators spaced apart in any predetermined configuration
on the posterior surface of the anterior lens element, as may be
required to impose a desired pattern of localized deflection on the
anterior lens element. As will be apparent to one of skill in the
art, an annular structure may be substituted for the individual
actuator depicted in FIG. 5, and the side walls of the actuator may
be of any suitable shape other than a bellows structure. For
example, the actuator may comprise a polymer that had been treated,
such as by application of bi-axial stress, to pre-orient the
polymer to stretch predominantly in a desired direction.
[0065] IOL 20 also may include coating 35 disposed on all interior
fluid-contacting surfaces within IOL 20, such as fluid channel 31
and well 32 and the surfaces defining cavity 34. Coating 35 is
configured to reduce or prevent diffusion of the index-matched
fluid used to drive actuator 24, and within cavity 34, from
diffusing into the polymer matrix of the lens components and/or to
prevent inward diffusion of external fluids into the IOL. The IOL
also may include coating 36, which comprises the same or a
different material than coating 35, disposed on the exterior
surfaces of the lens. Coating 36 is intended to serve as a barrier
to prevent the diffusion of fluids from the eye into the IOL or
from the IOL into the eye, and may be disposed on the entire
exterior surface of the optic portion and haptic portion, including
the anterior and posterior lens elements and haptics.
[0066] Alternatively, both coatings 35 and 36 may be layered onto a
single surface to prevent or reduce both ingress of bodily fluids
into the IOL or fluid circuit, and loss of index-matched fluid from
the interior spaces of the IOL. Coatings 35 and 36 preferably
comprise a suitable biocompatible polymer, perfluorinated
hydrocarbon, such as PTFE, inorganic (e.g., silicone dioxide) or
metallic layer (e.g., nickel-titanium) applied by any of a variety
of methods known in the art.
[0067] Operation of IOL 20 of FIGS. 4-6 is now described. IOL 20 is
implanted within a patient's capsule after extraction of the native
lens using any suitable technique. When implanted, haptics 28 and
29 support the IOL so that optic portion 21 is centered along the
central axis of eye. When the ciliary muscles are in a contracted
state, the zonules and capsule are less taut, and the haptics 28
and 29 are in the undeformed state. In this condition, fluid
pressure applied by the fluid in the haptics, channel 31 and well
32 maintain actuator 24 fully extended, so that anterior lens
element 23 is deflected to its accommodated state.
[0068] When the ciliary muscles relax, the zonules pull the capsule
taut, thereby applying compressive forces on the anterior and
posterior surfaces of haptics 28, 29. These forces cause haptics
28, 29 to deform to the deformed state depicted by the dotted lines
in FIG. 5, thereby increasing interior volume 30 of haptics 29, 30.
Because there is only a predetermined amount of fluid contained
within the interior of haptics 28, 29, channel 31, well 32 and
actuator 24, the increased interior volume 30 in deformed haptics
28, 29 draws fluid from within actuator 24. This in turn causes
actuator 24 to shorten, thereby deflecting anterior lens element 23
to a less convex, unaccommodated state. Subsequent contraction and
relaxation of the ciliary muscles causes the foregoing process to
repeat, thereby providing a degree of lens accommodation that
mimics the accommodating action of the natural lens.
[0069] As described above, spherical lenses may introduce spherical
aberrations. The inner surface and thickness of anterior element 23
may be selected to provide an aspherical outer surface to lessen
the spherical aberration through the lens. The present invention is
directed to an IOL having another structural feature that alters
the shape of the dynamic lens surface to further lessen the effects
of spherical aberrations.
[0070] Referring to FIGS. 7A, 7B and 7C, an embodiment of optic
portion 41 of an IOL constructed in accordance with the principles
of the present invention is described. Optic portion 41 includes
anterior lens element 43, intermediate layer 45, actuator 44 and
substrate 46. In the present embodiment, intermediate layer 45 is
integral with actuator 44. Similar to the above-described
embodiment, the components of optic portion 41 are made of
light-transmissive materials, such as silicone or acrylic polymers
or other biocompatible materials as are known in the art of
intraocular lenses.
[0071] Actuator 44 includes projection 47 and flexible wall 48 that
circumscribes projection 47. Wall 48 forms a generally annular
undulation, or corrugation, and extends between a substantially
stationary portion of intermediate layer 45 and projection 47.
Similar to the above-described embodiment, actuator 44 is in fluid
communication with deformable haptics (not shown) that are used to
distribute a fluid between the haptics, channel 51 in substrate 46
and well 52 that is located adjacent actuator 44.
[0072] Deformation of the haptics by action of the ciliary muscles
causes the interior volume of the haptics to change, which may
either force fluid through channel 51 toward well 52 or draw fluid
through channel 51 from well 52. Forcing fluid into well 52 causes
the fluid pressure within well 52 to increase, which increases the
force placed on actuator 44. An increase in pressure in well 52
causes projection 47 to translate in an anterior direction.
Conversely, when fluid is drawn from well 52, pressure within well
52 decreases and projection 47 translates in a posterior direction.
In the present embodiment, translation of projection 47 is
permitted by flexing of the wall of actuator 44 adjacent projection
47. Projection 47 is coupled to anterior lens element 43 so that
movement of projection 47 causes anterior lens element 43 to
deform.
[0073] Anterior lens element 43 and intermediate layer 45 are
coupled to each other at their circumferences to provide a fluid
seal 42 between the two components. As a result of fluid seal 42,
fluid cavity 50 is formed between anterior lens element 43 and
intermediate layer 45. Anterior lens element 43 and intermediate
layer 45 may be coupled by adhering, welding or any other technique
recognized in the art for creating a fluid seal. For example, in an
embodiment, an index-matched adhesive, such as an acrylic monomer,
couples anterior lens element 43 and intermediate layer 45.
However, it will be appreciated that any biocompatible adhesive may
be employed.
[0074] Fluid cavity 50 is filled with a substantially fixed volume
of shaping fluid. Coatings may be applied to the surfaces of cavity
50 to reduce or prevent diffusion of the shaping fluid from cavity
50.
[0075] For the purpose of further discussion, optic portion 41 will
be described with reference to boundary zone 55, outer peripheral
zone 56, inner peripheral zone 57 and central zone 58. Boundary
zone 55 is located the furthest radially outward from the optical
axis of optic portion 41 and includes the sealed coupling between
anterior lens element 43 and intermediate layer 45. Boundary zone
55 includes a portion of cavity 50 located the furthest radially
outward from the optical axis and fluid seal 42.
[0076] Outer peripheral zone 56 is located adjacent and radially
inward from boundary zone 55. Outer peripheral zone 56 of optic
portion 41 includes a large portion of intermediate layer 45 and
cavity 50. In the present embodiment, anterior lens element 43 has
a reduced thickness and is flexible in outer peripheral zone 56. In
addition, the anterior surface of intermediate layer 45 may be
generally concave so that it curves away from anterior lens element
43, thereby forming an enlarged region of cavity 50 and an enlarged
space between anterior lens element 43 and intermediate layer
45.
[0077] Inner peripheral zone 57 is located adjacent and radially
inward from outer peripheral zone 56. Inner peripheral zone 57
includes a portion of cavity 50 that is located between anterior
lens element 43 and wall 48 of actuator 44.
[0078] Central zone 58 is located further radially inward from
inner peripheral zone 57. The optical axis of optic portion 41
extends through central zone 58 and central portion of anterior
lens element 43 and projection 47 are disposed within central zone
58.
[0079] As described above, deformation of the haptics by action of
the ciliary muscles and capsule causes the interior volume of the
haptics to change, thereby causing actuator 44 and anterior lens
element 43 to move. The portions of cavity 50 within each of
boundary zone 55, outer peripheral zone 56, inner peripheral zone
57 and central zone 58 each have a first volume when optic portion
41 is in the unaccommodated state shown in FIGS. 7A and 7B. When
movement of actuator 44 and translation of projection 47 causes
optic portion 41 to transition to the accommodated state, shown in
FIG. 7C, there is a resultant change in the shape of cavity 50 and
each of the portions of cavity 50 experiences a change to a second
volume.
[0080] During the transition of optic portion 41 from the
unaccommodated state to the accommodated state, the total volume of
cavity 50 remains constant, but the volume of portions of cavity 50
may change. In particular, the volumes of the inner peripheral and
central portions of cavity 50 generally increase as projection 47
translates and forces anterior lens element 43 anteriorly. The
increase in volume of those portions causes the shaping fluid
contained within cavity 50 to be drawn into that increased volume
from the outer peripheral and boundary portions of cavity 50. As
the shaping fluid is drawn from those outer portions, it reduces
pressure in those outer portions of cavity 50, thus causing the
outer portions of anterior lens element 43 to be drawn toward
intermediate layer 45, as shown in FIG. 7C, thereby reducing the
volume of those portions.
[0081] The shape of cavity 50 and resulting changes in volume of
the various portions of cavity 50 result in the central and inner
peripheral portions of anterior lens element 43 being generally
more convex than the boundary and outer peripheral portions of
cavity 50. It will be appreciated that the boundary and outer
peripheral portions of anterior lens element 43 may be convex,
concave or flat as desired because due to the stopping down of the
pupil and/or the Stiles-Crawford Effect light passing through those
portions may be less significant for proper vision.
[0082] It should be appreciated that the shape of cavity 50 may be
selected by creating intermediate layer 45 and anterior lens
element in any desired shape and thickness. The shapes and
thicknesses of those components may be used to create any desired
changes in the volumes of the various portions of the cavity 50 and
to create any desired pressure changes during movement of actuator
44. Furthermore, the change in volume of the various portions of
cavity 50 may be controlled by adjusting the elasticity of each of
the corresponding portions of anterior lens element 43,
intermediate layer 45 and actuator 44.
[0083] It should also be appreciated that the boundary condition,
i.e., the configuration of the interface of intermediate layer 45
and anterior lens element 43 may be selected to create relative
motion between those components in boundary zone 55. For example,
as shown in the present embodiment, anterior lens element 43 and
intermediate layer 45 may be rigidly fixed so that there is no
relative movement between the components at the location of fluid
seal 42 between the parts. Alternatively, the sealed coupling
between anterior lens element 43 and intermediate layer 45 may be
configured to allow limited relative motion between the parts. For
example, fluid seal 42 may include a bellows or hinge member that
allows relative motion.
[0084] Referring now to FIGS. 8A and 8B, an embodiment of an IOL
constructed in accordance with the principles of the present
invention is described. IOL 60 utilizes a sealed cavity 70 and
shaping fluid to create an aspherical accommodated lens.
Additionally, IOL 60 includes backstops 73 for maximizing the
hydraulic forces generated by asymmetric loads imposed during
transition of the lens capsule between the accommodated and
unaccommodated states. IOL 60 generally includes optic portion 61
and haptic portion 62, both of which are similar in construction to
the corresponding portions of the embodiment of FIGS. 4-6. In
particular, optic portion 61 includes anterior lens element 63,
actuator 64, intermediate layer 65 and substrate 66.
[0085] Haptic portion 62 includes haptics 68, 69, each of which
defines interior volume 67 that is in fluid communication with
channel 71 and well 72 formed in substrate 66. Because the
structure of the components is substantially identical to the
corresponding structures of IOL 20 described above, these
components will not be described in further detail.
[0086] In accordance with the principles of the present invention,
IOL 60 further comprises cavity 70 which is a fluidly sealed cavity
defined by anterior lens element 63 and intermediate layer 65.
Cavity 70 contains a substantially fixed volume of shaping fluid.
Which is distributed through cavity 70 when actuator 64 forces
anterior lens element 63 to move under the influence of haptic
portion 62.
[0087] In the present embodiment, intermediate layer 65 is a
separate component from actuator 64 and as a result, a fluid seal
is provided both between anterior lens element 63 and intermediate
layer at the periphery of optic portion 61 as well as between
intermediate layer 65 and actuator 64 near the center of optic
portion 61.
[0088] IOL 60 further comprises backstops 73 that rigidly support
at least a portion of the circumference of each of haptics 68 and
69. Backstops 73 are coupled to a portion of the outer surface of
each haptic 68, 69 and are cantilevered members that generally
follow the substantially toroidal shape of haptics 68, 69.
[0089] The present embodiment combines the shaping fluid included
in cavity 70 and backstops 73 to more efficiently convert movement
of a lens capsule into hydraulic forces in IOL 60 and to prevent or
reduce resulting spherical aberration.
[0090] Referring now to FIGS. 9A and 9B, an alternative embodiment
of an IOL constructed in accordance with the principles of the
present invention is described. IOL 80 generally includes optic
portion 81 and haptic portion 82, both of which are similar in
construction to the corresponding portions of the embodiments
described above. In particular, optic portion 81 includes anterior
lens element 83, actuator 84, intermediate layer 85 and substrate
86.
[0091] Haptic portion 82 includes haptics 88 and 89, each of which
define interior volume 87 that is in fluid communication with
channels 91 and well 92 that are formed in substrate 86. Because
the structure of the components is substantially identical to the
corresponding structures of the previously described embodiment
these components will not be described in further detail.
[0092] IOL 80 also includes sealed cavity 90 that contains shaping
fluid. As described above, movement of actuator 84 and anterior
lens element 83 causes changes in the volumes of portions of cavity
90 which in turn causes the shaping fluid to be redistributed
within cavity 90. The redistribution of the shaping fluid causes
changes in pressure within cavity 90 which causes further
deflection of anterior lens element 83 generally to an aspheric
shape.
[0093] Backstops 93 also are provided in IOL 80, and extend from
optic portion 81 to haptics 88 and 89. Backstops 93 are generally
shaped as sections of a disk or cone. Similar to the backstops
described with regard to the previous embodiment, backstops 93
provide support to a portion of haptics 88, 89 so that movement of
the lens capsule is more efficiently converted into deformation of
haptics 88, 89 rather than into translation of haptics 88, 89.
[0094] Referring to FIGS. 10A and 10B, an additional embodiment of
an IOL constructed in accordance with the principles of the present
invention is described. Similar to the previously described
embodiments, IOL 100 generally includes optic portion 101 and
haptic portion 102. Optic portion 101 includes anterior lens
element 103, substrate 106 and actuator 104 interposed
therebetween. In the present embodiment, actuator 104 also forms an
intermediate layer and substrate 106 may function as a posterior
lens element.
[0095] In accordance with the present invention, IOL 100 includes a
sealed cavity 110 that is formed between intermediate layer 105,
actuator 104 and anterior lens element 103. Cavity 110 is filled
with a substantially constant volume of shaping fluid that is
redistributed through cavity 110 when actuator 104 moves anterior
lens element. Cavity 110 is fluidly sealed by a seal between
anterior lens element 103 and intermediate layer 105 formed by the
circumferential coupling of those components.
[0096] Haptic portion 102 includes haptics 108 and 109, each of
which defines interior volume 100 that is in fluid communication
with channels (not shown) and well 101 that are formed between
actuator 104 and substrate 106. Each haptic 108, 109 is integrated
into substrate 106 and extends backstop portion 113 of substrate
106. Backstop 113 is configured to provide support over a posterior
portion of haptics 108, 109. It should be appreciated that the
dimensions of haptics 108 and 109 and backstop portion 113 are
selected so that backstop portion 113 is significantly more rigid
than haptics 108, 109 so that haptics are permitted to deform when
acted upon by the lens capsule.
[0097] Additionally, load shelf 114 is provided on an anterior
portion of each haptic 108, 109 that is approximately diametrically
opposed to backstop 113. Shelf 104 includes anterior surface 115
that is configured to engage a portion of the anterior wall of a
lens capsule. Anterior surface 115 provides a greater surface area
upon which force may be exerted on haptic 108, 109 by the lens
capsule. As a result, energy from movement of the capsular bag may
be captured more efficiently and converted into deformation of
haptic 109, 98 and hydraulic forces within IOL 100.
[0098] The present embodiment also illustrates an alternative
boundary condition between anterior lens element 103 and
intermediate layer 105. In particular, anterior lens element 103
includes an undulation similar to that of actuator 104 and a wall
section of anterior lens element 103 that is oriented in the
anterior/posterior direction is coupled to intermediate layer 105.
As a result of that wall section, the peripheral portion of
anterior lens element 103 may be permitted to bend more freely when
actuator 104 deforms anterior lens element 103 and redistributes
the shaping fluid within cavity 110.
[0099] Referring now to FIGS. 11A and 11B, an embodiment of an IOL
constructed in accordance with the principles of the present
invention is described. IOL 120 utilizes sealed cavity 130 and
shaping fluid to create an aspherical accommodated lens while
maximizing the hydraulic forces generated by asymmetric loads
imposed during transition of the lens capsule between the
accommodated and unaccommodated configurations. IOL 120 generally
includes optic portion 121 and haptic portion 122, both of which
are similar in construction to the corresponding portions of the
embodiments described above. In particular, optic portion 121
includes anterior lens element 123, actuator 124, intermediate
layer 125 and substrate 126.
[0100] Haptic portion 122 includes haptics 128, 129, each of which
define interior volume 127 that is in fluid communication with
channels 131 and well 132 that are formed in substrate 126. Because
the structure of the components is substantially identical to the
corresponding structures of the embodiments described above, these
components will not be described in further detail.
[0101] IOL 120 also includes capsule support members 135 that are
located external of haptics 128, 129. Support members 135 are
tab-shaped features that extend radially outward and are configured
to engage the inner wall of a lens capsule so that the capsule is
held in a more taut configuration so that engagement between
haptics 128, 129 and the lens capsule is maintained when the
ciliary muscles are relaxed or contracted. Maintaining that
engagement more efficiently converts movement of the lens capsule
to deformation of haptics 128, 129. Support members 135 are
preferably located adjacent to the coupling of haptics 128, 129 to
optic portion 121, because deformation of that portion of haptics
128, 129 is not relied upon for moving fluid in IOL 120. It should
be appreciated however that support members 135 may be located
anywhere that will not prevent haptics 128, 129 from deforming
sufficiently to transition optic portion 121 between the
accommodated and unaccommodated configurations.
[0102] Referring now to FIG. 12, an embodiment of an IOL
constructed in accordance with the principles of the present
invention is described. IOL 140 utilizes a sealed cavity and
shaping fluid to create an aspherical accommodated lens while
maximizing the hydraulic forces generated by asymmetric loads
imposed during transition of the lens capsule between the
accommodated and unaccommodated configurations. IOL 140 generally
includes optic portion 141 and haptic portion 142, both of which
are similar in construction to the corresponding portions of the
previously described embodiments.
[0103] The present embodiment illustrates an alternative
construction of support members 145. Support members 145 are
generally wires that circumscribe haptic portion 142 radially
outward from each of haptics 148, 149. Each support member 145 is
preferably coupled to haptic portion 142 where each of haptics 148,
149 is coupled to optic portion 141.
[0104] Support members 145 are configured to engage the inner wall
of a lens capsule so that the capsule is held in a more taut
configuration so that engagement between haptics 148, 149 and the
lens capsule is maintained when the ciliary muscles are relaxed or
contracted. Maintaining that engagement more efficiently converts
movement of the lens capsule to deformation of haptics 148,
149.
[0105] In addition to utilizing the sealed cavities containing a
fixed volume of shaping fluid, the flexibilities and shapes of the
components may be selected to tailor the influence of the shaping
fluid. In particular, the thickness and material of the anterior
lens component may be selected to provide an desired deflection. In
addition, the shape of the sealed cavity may be selected by
altering the shapes of the adjacent components to provide any
desired change in volume for any portion of the cavity.
[0106] It should be appreciated that although each embodiment has
been described having one sealed cavity, any number of sealed
cavities containing shaping fluid may be included. For example,
sealed cavities may be included adjacent to any desired portion of
the lens element so that discrete portions of the lens element may
be shaped in a desired fashion.
[0107] While preferred illustrative embodiments of the invention
are described above, it will be apparent to one skilled in the art
that various changes and modifications may be made therein without
departing from the invention. The appended claims are intended to
cover all such changes and modifications that fall within the true
spirit and scope of the invention.
* * * * *