U.S. patent application number 15/997594 was filed with the patent office on 2018-10-04 for intraocular lens with shape changing capability to provide enhanced accomodation and visual acuity.
The applicant listed for this patent is JOHNSON & JOHNSON SURGICAL VISION, INC.. Invention is credited to Daniel G. Brady, Scott J. Catlin, Edward P. Geraghty, Huawei Zhao.
Application Number | 20180280134 15/997594 |
Document ID | / |
Family ID | 48430956 |
Filed Date | 2018-10-04 |
United States Patent
Application |
20180280134 |
Kind Code |
A1 |
Brady; Daniel G. ; et
al. |
October 4, 2018 |
INTRAOCULAR LENS WITH SHAPE CHANGING CAPABILITY TO PROVIDE ENHANCED
ACCOMODATION AND VISUAL ACUITY
Abstract
An intraocular lens for providing a range of accommodative
vision, an extended depth of focus, or enhanced performance through
the asymmetric transfer of ocular forces to the lens. The
intraocular lens contains an optic and a haptic. The shape and/or
material of the haptic results in the transmission of ocular forces
to particular regions in the optic. Greater forces applied to
particular regions result in deformation of that region and
increased power.
Inventors: |
Brady; Daniel G.; (San Juan
Capistrano, CA) ; Catlin; Scott J.; (Pittsford,
NY) ; Geraghty; Edward P.; (Rancho Santa Margarita,
CA) ; Zhao; Huawei; (Irvine, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JOHNSON & JOHNSON SURGICAL VISION, INC. |
Santa Ana |
CA |
US |
|
|
Family ID: |
48430956 |
Appl. No.: |
15/997594 |
Filed: |
June 4, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14804240 |
Jul 20, 2015 |
9987125 |
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15997594 |
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13462114 |
May 2, 2012 |
9084674 |
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14804240 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2002/1682 20150401;
A61F 2250/0018 20130101; A61F 2002/1681 20130101; A61F 2002/1689
20130101; A61F 2/1624 20130101; A61F 2/1618 20130101; A61F 2/1635
20130101 |
International
Class: |
A61F 2/16 20060101
A61F002/16 |
Claims
1. An intraocular lens, comprising: an optic adapted to focus light
on the retina when disposed in the eye, the optic having a first
zone having a distance vision power and a second zone being
adjustable through a range of powers greater than the distance
vision power, the first zone being intersected by the central
optical axis, the second zone being off-set from the first zone;
and a haptic, comprising: an outer annular member; an inner annular
member disposed inside at least the second zone of the optic; and a
plurality of arms extending between the inner and outer annular
members; wherein the intraocular lens is adapted to respond to
ocular forces to adjust the power of the second zone.
2. The intraocular lens of claim 1, wherein the inner annular
member comprises a ring segment subtending an arc of 180 degrees or
less between first and second ends, the first and second ends being
connected by a transverse member extending across the optical area,
the second zone being disposed between the ring segment and the
transverse member.
3. The intraocular lens of claim 1, wherein the inner annular
member comprises a first arcuate portion having a first stiffness
and a second annular portion having a second stiffness, the second
annular portion bounding a portion of the second zone.
4. The intraocular lens of claim 3, wherein the second annular
portion has a radial thickness that is less than that of the first
annular portion.
5. The intraocular lens of claim 1, wherein the intraocular lens is
reinforced in the first zone such that power increasing deformation
is concentrated in the second zone.
6. The intraocular lens of claim 1, wherein a portion of the first
zone bordering the second zone maintains the distance vision power
when the power of the second zone is increased.
7. The intraocular lens of claim 1, wherein the outer annular
member comprises a first portion disposed about a distance power
region and a second portion disposed around a near power region,
the first portion adapted to transfer a lesser amount of ocular
force to the optic than the second portion.
8. The intraocular lens of claim 1, wherein the outer annular
member is configured to transfer ocular forces in a manner that
induces the power in at least the second zone toward a near vision
power.
9. The intraocular lens of claim 8, wherein the optic comprises a
third zone having a range of powers greater than the distance
vision power and including a maximum power less than a near vision
power, the outer annular member configured to induce at least the
maximum power in the third zone and the near vision power in the
second zone.
10. The intraocular lens of claim 1, wherein some of the plurality
of arms include voids.
11. The intraocular lens of claim 1, wherein the outer annular
member is spaced apart from the optic by the plurality of arms
along a direction perpendicular to the optical axis.
12. The intraocular lens of claim 1, wherein the outer annular
member comprises a continuous ring adapted to be disposed at the
equator of a capsular bag and the inner annular member comprises a
continuous ring adapted to be disposed inside the optic.
13. The intraocular lens of claim 1, wherein the second zone is
adapted to provide at least 2 Diopters of add power.
14. An intraocular lens, comprising: an optic comprising a fixed
power region and an add power region; a haptic comprising: an inner
portion having a stiff region disposed inside the fixed power
region and a force transfer portion disposed inside the add power
region; and a plurality of arms extending radially away from the
force transfer portion toward an outer periphery of the intraocular
lens; wherein the intraocular lens is adapted to respond to ocular
forces to alter the add power region the increase the power of the
add power region.
15. The intraocular lens of claim 14, wherein the haptic further
comprises a plurality of arms extending radially away from the
stiff region toward the outer periphery of the intraocular lens and
an outer ring coupled with outer ends of the arms.
16. The intraocular lens of claim 14, wherein the haptic includes a
plurality of arms having proximal ends coupled with an inner
arcuate member and distal ends disposed adjacent an outer periphery
of the intraocular lens, the add power region being disposed
between the inner arcuate member and the fixed power region.
17. The intraocular lens of claim 16, wherein the haptic includes
an intermediate arcuate member disposed between the inner arcuate
member and the distal ends of the arms, the add power region
including an arcuate band disposed between the inner and
intermediate arcuate members.
18. The intraocular lens of claim 17, wherein the arcuate band
deforms to provide an intermediate power when an ocular force is
applied to the haptic and wherein the region between the inner
arcuate member and the fixed power region deforms to provide a near
power when the same ocular force is applied to the haptic.
19. The intraocular lens of claim 16, wherein the fixed power
region comprises a continuous expanse of a majority of the area of
the optic including a central axis of the optic and the add power
region comprises a region off-set from the central axis of the
optic.
20. An intraocular lens, comprising: an optic adapted to be
deformed when subjected to a compressive ocular force; a haptic
adapted to apply, in response to a uniform annular compressive
ocular force, a first compressive force to a first portion of the
optic and a second compressive force to a second portion of the
optic, the second ocular force being different from the first
ocular force; wherein the first and second portions of the optic
change power when subjected to the compressive ocular force; and
wherein the first portion of the optic changes power by an amount
greater than the second portion.
21. The intraocular lens of claim 20, wherein the haptic comprises
a first plurality of arms configured to cooperate to apply the
first compressive force and a second plurality of arms configured
to cooperate to apply the second compressive force.
22. The intraocular lens of claim 20, wherein the haptic comprises
an annular structure comprising a first segment disposed about a
first portion of the optic and a second segment disposed about a
second portion of the optic, the first segment being adapted to
apply the first compressive force and the second segment being
adapted to apply the second compressive force.
23. The intraocular lens of claim 22, wherein the first segment is
stiffer than the second segment.
24. The intraocular lens of claim 22, wherein the first segment has
a first radius of curvature and the second segment has a second
radius of curvature.
25. The intraocular lens of claim 20, wherein the haptic comprises
an oval structure configured to transmit a greater force to the
optic along a minor axis thereof and a lesser force to the optic
along a major axis thereof.
26. The intraocular lens of claim 20, wherein change in power of
the second portion compensates for an optical aberration of an
ocular system such that the ocular system and intraocular lens
together focus light in both the first and second portions of the
optic to the same point simultaneously.
27. The intraocular lens of claim 20, wherein change in power of
the second portion induces an optical aberration of an ocular
system such that the ocular system and intraocular lens together
produce enhanced depth of focus.
28-36. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application and claims
priority to U.S. application Ser. No. 13/462,114, filed on May 2,
2012, the entire contents of which are hereby incorporated by
reference in its entirety for all purposes as if fully set forth
herein.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention is directed to intraocular lenses, and
more particularly to accommodating intraocular lenses having more
than one focus, an extended depth of focus, or enhanced performance
through asymmetric transfer of ocular forces in the lenses.
Description of the Related Art
[0003] A human eye can suffer diseases that impair a patient's
vision. For instance, a cataract may increase the opacity of the
lens, causing blindness. To restore the patient's vision, the
diseased or damaged lens may be surgically removed and replaced
with an artificial lens, known as an intraocular lens, or IOL. An
IOL may also be used for presbyopic lens exchange or other elective
ocular surgical procedures.
[0004] Monofocal IOLs have a single focal length, or, equivalently,
a single power. Unlike the eye's natural lens, which can adjust its
focal length within a particular range in a process known as
accommodation, these single focal length IOLs cannot accommodate
and thus provide clear vision over a limited range of distances. As
a result, distant objects may appear in focus, while objects at a
normal reading distance from the eye may appear blurred.
[0005] Vision over a broader range of distances can be obtained
either through the use of a multifocal lens, which provides
different foci configured to produce overlapping focused images for
different object distances, or a lens configured to provide an
extended depth of focus or depth of field, through for example, an
aspheric surface. While such lenses can improve the overall vision
range, there may also be an associated reduction in visual acuity
or overall visual quality, as well as dysphotopsias.
[0006] Another approach is to use an accommodating IOL, which can
adjust its axial position, shape, and/or thickness to effect an
optical power change within a particular range, similar to the
eye's natural lens. As a result, the patient can clearly focus on
objects in a range of distances from the eye, rather than at a
single distance, or a limited number of set distances. This ability
to accommodate is of tremendous benefit for the patient, and more
closely approximates the patient's natural vision than a single
focal length IOL. One of the challenges in accommodating IOLs is
providing a sufficient range of accommodation with the limited
amount of ocular force available from the ciliary muscle.
Additional challenges with IOLs, including accommodating IOLs
include optical aberrations, such as astigmatism, coma, spherical
aberration, for example.
SUMMARY OF THE INVENTION
[0007] Embodiments of the present invention are directed to devices
and methods for providing accommodative vision. In one aspect, an
intraocular lens is provided that comprises an adjustable optic
adapted to focus light on the retina when disposed in the eye and a
haptic or mounting structure that is operably coupled to the optic.
The intraocular lens is asymmetric in at least one aspect that
concentrates deformation of the optic to enhance the accommodative
effect or for other optical benefits, as discussed below.
[0008] In one embodiment the optic has a first zone that has a
distance vision power and a second zone that has a range of powers
greater than the distance vision power. The range of powers of the
second zone includes a near vision power. The first zone is
intersected by a central optical axis and the second zone is
off-set from the first zone. The haptic includes an outer annular
member and an inner annular member. The inner annular member can be
disposed inside at least the second zone of the optic. The haptic
also includes a plurality of arms extending between the inner and
outer annular members. The intraocular lens is adapted to respond
to ocular forces to adjust the power of the second zone toward the
near vision power.
[0009] In certain embodiments, the range of powers in the second
zone refers to the instantaneous maximum power of the second zone
as it is being deformed through its range of accommodation. In
other embodiments, a range of powers is provided at each stage of
accommodation, for example including an extended depth of focus
configuration at least in the fully accommodated state.
[0010] In another embodiment, an intraocular lens is provided that
includes an adjustable optic and a haptic. The adjustable optic has
an optical area adapted to focus light on the retina when the
intraocular lens is disposed in the eye. The haptic includes a
plurality of arms connected at their distal ends by a ring disposed
adjacent an outer periphery of the intraocular lens. Some of the
arms are connected at their proximal end by a ring portion
subtending an arc of about 180 degrees or less between first and
second ends. The ring portion can comprise a plurality of ring
segments extending between adjacent arms. The first and second ends
of the ring portion are connected by a transverse member extending
across the optical area. The ring portion and transverse member of
the haptic are disposed inside the adjustable optic. The
intraocular lens has a first zone and a second zone, the second
zone being disposed between the transverse member and the ring
portion. The transverse member is disposed between the second zone
and the first zone. The intraocular lens has an unstressed
configuration in which first and second zones provide a first
optical power for distance vision and a stressed configuration in
response to ocular forces in which the second zone provides a
second optical power that is greater than the first optical
power.
[0011] In another embodiment, an intraocular lens is provided that
includes an optic and a haptic. The optic has a fixed power region
and an add power region. The haptic includes an inner portion
having a stiff region disposed inside the fixed power region and a
force transfer portion disposed inside the add power region. The
haptic also includes a plurality of arms extending radially away
from the force transfer portion toward an outer periphery of the
intraocular lens. The intraocular lens is adapted to respond to
ocular forces to alter the add power region and increase the power
of the add power region.
[0012] In another embodiment, an intraocular lens is provided that
includes an optic and a haptic. The optic comprises a fixed power
region and an add power region that includes a gel. The haptic
includes an inner portion, a force transfer portion, and a
plurality of arms. The inner portion is disposed inside the fixed
power region. The force transfer portion is disposed inside the add
power region. At least some of the arms extend radially away from
the force transfer portion toward an outer periphery of the
intraocular lens. The intraocular lens is adapted to respond to
ocular forces to preferentially apply a greater amount of force to
the add power region to increase the power of the add power
region.
[0013] In various embodiments, the haptic comprises a transparent
portion protruding into the adjustable optic. The intraocular lens
has a disaccommodative configuration in which an adjustable zone
has a base optical power and an accommodative configuration in
which the adjustable zone has an add optical power that is at least
about 1 Diopter greater than the base optical power, preferably at
least about 2 Diopters greater than the base optical power, and
even more preferably at least 3 Diopters, or even 4 Diopters,
greater than the base optical power. The adjustable zone can be
bordered by an annular zone having different optical powers when
the adjustable intraocular lens is in the accommodative
configuration and/or in the disaccommodative configuration.
[0014] As used herein "base optical power" or "base power" means
power (in Diopters) of an IOL or other ophthalmic lens or lens
system that is required to provide distant vision at the retina of
a subject eye. As used herein "add optical power" or "add power"
means a difference in power (in Diopters) between the power
required to provide distant vision and the power of the lens
portion having the add optical power. When the add optical power is
a positive quantity, it is the difference in power between power
required to provide distant vision and the power required to focus
light from an object at some finite distance from the eye.
Alternatively, the add optical power may be a negative
quantity.
[0015] In another aspect of the present invention, a method of
providing accommodative vision to a subject comprises providing an
intraocular lens according to an embodiment of the invention that
includes an optic having an off-set add power region and/or
asymmetric force transfer capability. The method also comprises
placing the intraocular lens into the eye of a subject in a
disaccommodated configuration in which the off-set add power region
has a base optical power or in which an optic of an intraocular
lens configured for asymmetric loading is unstressed. The
intraocular lens is adjustable to an accommodated configuration in
which the off-set add power region has an add optical power that is
at least 1 to 4 Diopters greater than the base optical power. The
off-set add power region and a portion of the optic spaced apart
from the add power region may simultaneously have different optical
powers when the intraocular lens is in the accommodated
configuration and/or when the optic is in the disaccommodative
configuration. In another method, a further aspect comprises
asymmetrically loading an optic to compensate for anatomical
asymmetry. Anatomical asymmetry may include optical aberrations due
to asymmetry in the eye system and/or non-uniform loading due to
damage to the ocular muscles or connective tissues.
[0016] Alternatively, the intraocular lens may be placed into the
eye in an accommodated configuration in which the off-set add power
zone has the add optical power, wherein the intraocular lens is
adjusted to a disaccommodated configuration in which the off-set
add power zone has a base optical power that is suitable for
providing intermediate and/or distant vision. In any event, when
the intraocular lens is in the accommodated configuration, the
off-set add power zone and/or spaced apart zone is suitable for
providing vision for objects that are relatively close to the
subject (e.g., 12 to 24 inches from the subject) or objects at
intermediate distances (e.g., 2 to 5 feet from the subject). When
the intraocular lens is in the disaccommodated configuration, the
off-set add power zone and/or spaced apart zone is suitable for
providing vision for objects that are distant (e.g., greater than
20 feet from the subject) and/or objects at intermediate
distances.
[0017] In another embodiment, an intraocular lens is provided that
includes an optic adapted to be deformed by a haptic when subjected
to a compressive ocular force. The haptic is adapted to apply, in
response to a uniform annular compressive ocular force, a first
compressive force to a first portion of the optic and a second
compressive force to a second portion of the optic. The second
ocular force is different from the first ocular force. The first
and second portions of the optic change power when subjected to the
compressive ocular force. The first portion of the optic changes
power by an amount greater than the second portion. The haptic may
include a plurality of arms connected at their distal ends by a
ring disposed adjacent an outer periphery of the intraocular lens,
some of the arms being connected at their proximal end by a ring
portion subtending an arc of about 180 degrees or less between
first and second ends, the first and second ends being connected by
a transverse member extending across the optical area, the ring
portion and transverse member of the haptic being disposed inside
the adjustable optic; wherein the intraocular lens has a first zone
and a second zone, the second zone being disposed between the
transverse member and the ring portion, the transverse member being
disposed between the second zone and the first zone; wherein the
intraocular lens has an unstressed configuration in which first and
second zones provide a first optical power for distance vision and
a stressed configuration in response to ocular forces in which the
second zone provides a second optical power that is greater than
the first optical power.
[0018] In another embodiment, an intraocular lens is provided that
includes an optic and a haptic. The optic has a non-uniform
geometry and is adapted to be deformed when subject to a
compressive ocular force. The haptic is adapted to apply a
compressive force along a first axis of the optic in response to
the compressive ocular force and a compressive force along a second
axis of the optic in response to the compressive ocular force. The
compressive forces cause a change in curvature along the first axis
that is greater than a change of curvature along the second axis.
In another embodiment, rather than deform along a specific axis in
response to an ocular force, the optic may vault anteriorly or
posteriorly along a particular axis in response to an ocular
force.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Embodiments of the present invention may be better
understood from the following detailed description when read in
conjunction with the accompanying drawings. Such embodiments, which
are for illustrative purposes only, depict novel and non-obvious
aspects of the invention. The drawings include the following
figures.
[0020] FIG. 1 is a plan drawing of a human eye having an implanted
intraocular lens in an accommodative or "near" state.
[0021] FIG. 2 is a plan drawing of the human eye of FIG. 1 in a
disaccommodative or "far" state.
[0022] FIG. 3 is an isometric view of an intraocular lens according
to a first embodiment showing an optic operably coupled to a
haptic.
[0023] FIG. 4 is an isometric view of the haptic only from the
intraocular lens shown in FIG. 3.
[0024] FIG. 5 is a cross-sectional isometric view of the
intraocular lens of FIG. 3 showing a haptic segment operably
coupled to an optic segment.
[0025] FIG. 6 is a cross-sectional view through the section 6-6 of
FIG. 3 showing a portion of a haptic protruding into an optic and
the intraocular lens in a disaccommodative state.
[0026] FIG. 7A is a cross-sectional view of the intraocular lens
shown in FIG. 6 in an accommodative state.
[0027] FIG. 7B is a cross-sectional view of an intraocular lens
showing a portion of a haptic protruding into an optic, the haptic
having a larger circumference or perimeter toward the central zone
of the optic and a smaller circumference or perimeter at the edge
of the optic.
[0028] FIG. 8 is a block diagram of a method of implanting an
intraocular lens and providing accommodative vision.
[0029] FIG. 9 is a front view of an intraocular lens according to a
second embodiment.
[0030] FIG. 10 is a cross-sectional view through the section 10-10
of FIG. 9.
[0031] FIG. 11 is a front view of the haptic only from the
intraocular lens shown in FIG. 9.
[0032] FIG. 12 is a cross-sectional view through the section 12-12
of FIG. 11.
[0033] FIG. 13 is an isometric view of an intraocular lens
according to a third embodiment.
[0034] FIG. 14 is a cross-sectional isometric view of the
intraocular lens of FIG. 13 showing a haptic segment operably
coupled to an optic segment.
[0035] FIG. 15 is a front view of the intraocular lens shown in
FIG. 13
[0036] FIG. 16 is a front view of an intraocular lens according to
a fourth embodiment.
[0037] FIG. 16A is a cross-sectional view of the intraocular lens
of FIG. 16 taken at 16A-16A.
[0038] FIG. 17 is a partial view of the optical area of the
intraocular lens of FIG. 16.
[0039] FIG. 18 is a front view of a haptic of the intraocular lens
shown in FIG. 16.
[0040] FIG. 19A is a plot illustrating the optical power of one
embodiment of an intraocular lens shown in FIG. 16 as a function of
transverse location and accommodative state.
[0041] FIG. 19B is a plot illustrating the optical power of another
embodiment of an intraocular lens similar to that shown in FIG. 16
as a function of transverse location and accommodative state.
[0042] FIG. 20 is a front view of a variation of the intraocular
lens of FIG. 16.
[0043] FIG. 21 is a plan view of another embodiment of an
intraocular lens having a stiff sublayer disposed therein and a
plurality of add power foci.
[0044] FIG. 22 is a plan view of another embodiment of an
intraocular lens having a stiff sublayer and an add power region
spaced from the geometric center of the lens.
[0045] FIGS. 23A-23F illustrate a variety of intraocular lens
structures that asymmetrically respond to symmetrical ocular
forces.
[0046] FIGS. 24A-24C illustrate an intraocular lens structure that
asymmetrically responds to symmetrical ocular forces.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0047] In a healthy human eye, the natural lens is housed in a
structure known as the capsular bag. During natural accommodation,
the capsular bag is driven by a ciliary muscle and zonular fibers
(also known as zonules) in the eye, which can pull on the capsular
bag to change its shape. The change in shape of the capsular bag
generally deforms the natural lens in order to change its power
and/or the location of the lens, so that the eye can focus on
objects at varying distances away from the eye in a process known
as accommodation.
I. Intraocular Lenses Adapted to Accomodate by Changing the Shape
of an Optic
[0048] Embodiments described herein are directed to intraocular
lenses that advantageously use ocular forces, such as those
produced by the ciliary muscle, zonules, and/or capsular bag, to
change the shape of the lens optic. Such an accommodating lens may
produce improved vision over a lens with a fixed power and location
that does not accommodate. As used herein the term "ocular force"
is a broad term that includes a force that is sufficient to provide
accommodation in the eye of a healthy human subject.
[0049] FIG. 1 shows a human eye 10, after an accommodating
intraocular lens 11, according to an embodiment of this
application, has been implanted. Prior to surgery, the natural lens
occupies essentially the entire interior of the capsular bag 18.
After surgery, the capsular bag 18 may house the intraocular lens
11. Alternatively, the intraocular lens 11 may be configured to
directly engage the zonules or ciliary muscle.
[0050] Light enters the eye 10 from the left in FIG. 1 and passes
through the cornea 12, the anterior chamber 14, the pupil (defined
by the inner edge of the iris 16), and impinges on the intraocular
lens 11. After passing through the intraocular lens 11, light exits
the posterior wall 20 of the capsular bag 18, passes through the
vitreous body 32, and strikes the retina 22, which detects the
light and converts it to a signal transmitted through the optic
nerve 24 to the brain.
[0051] A well-corrected eye focuses an image at the retina 22. If
the intraocular lens 11 has too much or too little power, the
focused image shifts axially along the optical axis off of the
retina, toward or away from the lens 11. Note that the total power
of the eye (e.g., including the combined power of cornea 12 and the
intraocular lens 11) required to focus on a close or near object is
more than the power required to focus on a distant or far object.
The difference between the "near power" and "far power" is known
typically as the range of accommodation or the add power. A typical
range of accommodation or add power is about 2 to 4 diopters, but
may be significantly larger for younger human subjects.
[0052] The intraocular lens 11 may be designed so that its relaxed
or natural state is the "far" or "distant" condition (sometimes
referred to as a "disaccommodative biased" intraocular lens), the
"near" condition (an "accommodative biased" intraocular lens), or
some condition in between the two. As used herein, the terms
"natural state", "natural configuration", "relaxed state", and
"relaxed condition" can refer to a condition of an intraocular lens
in which no or minimal external forces (e.g., ocular forces from
the ciliary muscle, zonules, or capsular bag) are acting upon the
intraocular lens 11 or the optic 48 of an intraocular lens 40
(discussed below).
[0053] The capsular bag 18 is acted upon by the ciliary muscle 25
and the zonules 26, which distort the capsular bag 18 by stretching
it radially in a relatively thick band about its equator.
Experimentally, it is found that the ciliary muscle 25 and/or the
zonules 26 typically exert a total force of up to about 10 grams of
force, which is generally distributed uniformly around an
equatorial region of the capsular bag 18. In some patients,
non-uniform forces may be applied to the capsular bag 18, for
example, due to damage of the zonules, which can cause astigmatism
or other optical aberrations. As will be discussed in greater
detail below, some embodiments disclosed herein are adapted to
compensate for such non-uniformity.
[0054] Although the range of ocular force may vary from patient to
patient, the range of accommodation for each subject is generally
limited by the total ocular force available. Therefore, it is
generally preferred that the intraocular lens 11 be configured to
vary its power over the full range of accommodation in response to
this limited range of ocular forces (e.g., to provide at least 2
Diopters, preferably 3 Diopters or more preferably 4 Diopters of
accommodative power). In other words, it is desirable to have a
relatively large change in power for a relatively small driving
force. Alternatively, the effective range of accommodation may be
increased by incorporating a lens having a multifocal or extended
depth-of-focus configuration. As discussed in connection with FIGS.
16-22 below, focusing the add power to a region of the intraocular
lens can enhance the add power for that region and for the lens. As
discussed in connection with FIGS. 23-24, asymmetric force transfer
to an optic of an intraocular lens can counteract optical
aberrations due to non-uniform characteristics of the eye, or
alternatively may enhance such aberrations to achieve an extended
depth of focus.
[0055] The intraocular lens 11 generally has an optic 28 made of a
transparent, deformable and/or elastic material and a haptic 30
configured to hold the optic 28 in place and to mechanically
transfers forces from the eye (e.g., from the capsular bag 18 or
ciliary muscle 25) to the optic 28. The haptic 30 may have an
engagement member with a central recess that is sized to receive
the peripheral edge of the optic 28.
[0056] When the eye 10 is focused on a relatively close object, as
shown in FIG. 1, the ciliary muscle 25 is compressed, which causes
the zonules 26 to relax and allow the equatorial region of the
capsular bag 18 to contract. The capsular bag 18 in this state is
thicker at its center and has more steeply curved sides. As a
result, the power of the lens is relatively high (e.g., the radii
of curvature of one or both of the lens surfaces can decrease,
and/or the lens can become thicker, and/or the lens can move
axially), focusing the image of the relatively close object at the
retina 22. Note that if the lens could not accommodate, the focused
image of the relatively close object would, for an emmetropic eye,
be located behind the retina, and would appear blurred. Also, if
the eye has aberrations such as astigmatism, uniform power in all
diameters or segments of the lens would not produce satisfactory
vision. For some axes or segments, light would focus at the retina
and for others light would focus behind or in front of the
retina.
[0057] FIG. 2 shows a portion of the eye 10 focused on a relatively
distant object. To focus on the distant object, the zonules 26 are
retracted and the shape of the capsular bag 38 is thinner at its
center and has less steeply curved sides. This reduces the lens
power by flattening (i.e., lengthening radii of curvature and/or
thinning) the lens and/or moving the lens axially, thus placing the
image of the relatively distant object at the retina (not
shown).
[0058] For both the "near" case of FIG. 1 and the "far" case of
FIG. 2, the accommodating intraocular lens deforms and changes
shape in response to the ciliary muscle 25 and/or to the distortion
of the capsular bag 18. For the "near" object, the haptic 30
compresses the optic 28 at its edge, increasing the thickness of
the optic 28 at its center and more steeply curving its anterior
face 27 and/or its posterior face 29. As a result, the lens power
increases. For the "far" object, the haptic 30 expands, reducing
the compressive force on the edge of the optic 28, and thereby
decreasing the thickness of the optic 28 at its center and less
steeply curving (e.g., lengthening one or both radius of curvature)
its anterior face 27 and/or its posterior face 29. As a result, the
lens power decreases.
[0059] The specific degrees of change in curvature of the anterior
and posterior faces 27, 29 depend on the nominal curvatures.
Although the optic 28 is drawn as bi-convex, it may be
plano-convex, meniscus or other lens shapes in other embodiments.
In all of these cases, the optic 28 is compressed or expanded by
forces from the haptic to the edge and/or faces of the optic 28. In
addition, there may be some axial movement of the optic 28. In some
embodiments, the haptic 30 is configured to transfer the generally
symmetric radial forces symmetrically to the optic 28 to deform the
optic 28 in a spherically symmetric way.
[0060] In alternate embodiments discussed in connection with FIGS.
16-18, 20-24, the haptic 30 is configured non-uniformly (e.g.,
having different material properties, thickness, dimensions,
spacing, angles or curvatures), to allow for non-uniform transfer
of forces by the haptic 30 to the optic 28. The non-uniform force
transfer can enhance accommodative deformation in a sub-region to
increase the add power in that sub-region as discussed in
connection with FIG. 16-22. Also, for example, as discussed in
connection with FIGS. 23-24, non-uniform force transfer could be
used to compensate for astigmatism, coma or other asymmetric
aberrations of the eye/lens system, including asymmetric natural
forces in the ciliary process (e.g. if certain zonules are broken).
The optic 28 may optionally have one or more diffractive,
multifocal, and/or aspheric elements or surfaces, which can be
provided in the relaxed state or induced by forces transferred by
the haptic 30.
[0061] A. Intraocular Lenses With Cantilevered Haptic Arms
[0062] Referring to FIGS. 3-7B, in certain embodiments, an
intraocular lens 40 comprises an adjustable optic 42 and a haptic
44. The optic 42 has a clear aperture 43 that includes an anterior
surface 45 and a posterior surface 46. The clear aperture includes
a central zone 48 disposed about an optical axis OA and a
surrounding or annular zone 50 surrounding the central zone 48.
[0063] The haptic 44 may comprise a plurality of arms 52 that
protrude into the adjustable optic 42 and into the clear aperture
43. As discussed in connection with the embodiments below, a
modified haptic 44 is provided that is not uniform, for example in
which some of the arms 52 have greater capacity to transfer forces
to an optic and some with less force transfer capacity. In order to
provide a large clear aperture, the haptic 44 and arms 52 includes
transparent or refractive index matched (to the optic) portions 53
that protrude into the adjustable optic 42 and into the clear
aperture 43. The haptic 44 and arms 52 generally protrude into the
annular zone 50 but may also partially protrude into the central
zone 48. The haptic 44 and arms 52 are configured to deform the
central zone 48 in response to an ocular force from the ciliary
muscle and/or capsular bag, thereby changing the power of the
central zone 48 by at least 1 Diopter, preferably by at least 2
Diopters or at least 4 Diopters. By contrast the annular zone 50
may not change shape in response to an ocular force or changes
shape by an amount that produces less accommodative power change
than the power change of the central zone 48 (e.g., changes power
by less than 1 Diopter in response to an ocular force, less than
0.5 Diopters in response to an ocular force, or less than 0.25
Diopters in response to an ocular force).
[0064] The transparent portion 53 preferably has a transmissivity
of at least about 80%, more preferably of at least 90% or even 95%.
In some embodiments, the haptic 44 is made of a material that has a
refractive index that is substantially equal to the refractive
index of the optic 42, thus reducing or eliminating glare and
aberration problems that could be introduced by a mismatch in
refractive indices.
[0065] As used herein, the term "clear aperture" means the opening
of a lens or optic that restricts the extent of a bundle of light
rays from a distant source that can imaged or focused by the lens
or optic. The clear aperture can be circular and specified by its
diameter. Thus, the clear aperture represents the full extent of
the lens or optic usable for forming the conjugate image of an
object or for focusing light from a distant point source to a
single focus or to a plurality of predetermined foci, in the case
of a multifocal optic or lens. It will be appreciated that the term
clear aperture does not limit the transmittance of the lens or
optic to be at or near 100%, but also includes lenses or optics
having a lower transmittance at particular wavelengths or bands of
wavelengths at or near the visible range of the electromagnetic
radiation spectrum. In some embodiments, the clear aperture has the
same or substantially the same diameter as the optic 42.
Alternatively, the diameter of the clear aperture may be smaller
than the diameter of the optic 42, for example, due to the presence
of a glare or PCO reducing structure disposed about a peripheral
region of the optic 42.
[0066] The intraocular lens 40 and the optic 42 may be adjusted
between an accommodative state and a disaccommodative state. For
example, referring to FIG. 6, the optic 42 has a disaccommodative
configuration or state in which the central zone 48 has a base
optical power suitable for distant vision. Referring to FIG. 7A,
the intraocular lens 40 has an accommodative configuration or state
in which the central zone 48 has an add optical power suitable for
near or intermediate vision. The base optical power is generally
selected to provide a subject with distant vision (e.g., for
objects at distances greater than 10 feet from the subject), while
the add optical power of central zone 48 may be exploited to
provide a subject with better vision for near objects (e.g., for
objects at distances between about 12 to 24 inches from the
subject) and/or intermediate distances (e.g., for objects at
distances between 2 to 10 feet from the subject). Accordingly, the
add power is preferably at least about 1 Diopter greater than the
base optical power, more preferably at least 2 Diopters greater
than the base optical power, and even more preferably at least 3
Diopters or 4 Diopters greater than the base optical power. In the
illustrated embodiment, the add optical power is produced by the
thickening of the lens which leads to a decreased radius of
curvature of the anterior and posterior surfaces 45, 46, as
illustrated by comparing FIG. 7A to FIG. 6. In some embodiments,
the optical add power may be supplemented by accommodative movement
of the optic 40 in the anterior direction (e.g., away from the
retina of the eye). While the add optical power will generally
comprise a positive change in the accommodative power, the add
optical power may alternatively be a negative add power.
[0067] In certain embodiments, the surrounding zone 50 also has a
base optic power when the intraocular lens 40 is in a
disaccommodative state and an add optical power when the
intraocular lens 40 is in an accommodative configuration. The add
optical power of the surrounding zone 50 may be equivalent to the
add optical power of the central zone 48. Alternatively, the add
optical power of the surrounding zone 50 may be greater than or
less than the add optical power of the central zone 48. This
difference in the add power between the central and surrounding
zones 48, 50 may be the result of differences in how forces on the
haptic 44 are transferred to the zones 48, 50, as well as the shape
of the haptics in the various zones. By way of nonlimiting example,
a haptic with a larger axial thickness at the edge of optic which
then tapers as it protrudes into the optic may have a greater
effect on the surrounding zone as opposed to the central zone.
Conversely a haptic with a small axial thickness at the edge of the
optic and a larger axial thickness toward the central zone may have
a greater effect on the central zone as opposed to the surrounding
zone as shown in FIG. 7B.
[0068] Other modified intraocular lens embodiments discussed below
provide add power in a region located only on one side of a
diameter of an optic or in a particular portion or along a
particular axis of the optic. The ocular forces are concentrated
into a particular region to enhance add optical power in that
region.
[0069] In addition to providing accommodative power, the central
and surrounding zones 48, 50 may combine, in certain preferred
embodiments, to provide a multifocal lens when the intraocular lens
is in the accommodative state, the disaccommodative states, and/or
at intermediate states therebetween. Thus, for any given state or
configuration of the central and annular zones 48, 50, the
intraocular lens 40 may be configured to generally provide an
extended depth of focus or multiple foci that allows resolution of
objects at varying distances (e.g., simultaneously providing near
and intermediate vision, or simultaneously providing intermediate
and distant vision).
[0070] The multifocality of the intraocular lens 40 (e.g., the
differences in optical power of the central and surrounding zones
48, 50) may be produced by a radius of curvature between the
anterior and/or posterior surfaces 45, 46 of the central zone 48
and the surrounding zone 50. For example, referring to FIGS. 6 and
7A, the radius of curvature of the anterior and posterior surfaces
45, 46 in the region of central zone 48 is less than the radius of
curvature of those surfaces in the region of the surrounding zone
50, both in the accommodative state (FIG. 7A) and disaccommodative
state (FIG. 6). It will be appreciated that the differences in the
radiuses of curvature in the central and annular zones 48, 50 have
been exaggerated for illustrative purposes. In some embodiments,
the larger radius of curvature in the surrounding zone 50 is
selected to provide distant vision, while the smaller radius of
curvature of the central zone 48 is selected to provide a larger
optical power suitable for intermediate vision and/or near vision.
In some embodiments, the difference in optical power of the two
zones 48, 50 is at least partially provided by a diffractive
grating or phase plate that is placed on one or both surfaces of
the central zone 48 and/or the surrounding zone 50.
[0071] In the illustrated embodiment, the central zone 48 has a
greater optical power than the surrounding zone 50. Alternatively,
the central zone 48 may have the same or less optical power than
the surrounding zone 50 when the intraocular lens 40 is in the
accommodative configuration, the disaccommodative configuration, or
in some state between the accommodative and disaccommodative
configurations. In some embodiments, the zones 48, 50 are
configured to have the same optical power (e.g., to be a monofocal
lens having substantially a single focus) when the intraocular lens
40 is in either the accommodative state or disaccommodative state.
Alternatively, the zones 48, 50 may be configured to have the same
optical power at an intermediate state of the intraocular lens 40
and different optical powers when the intraocular lens 40 is in
either the accommodative state or disaccommodative state.
[0072] The diameter of central and surrounding zones 48, 50 may
selected to provide a predetermined mix of near, distant, and/or
intermediate vision that varies as a function of lighting
conditions (e.g., as a function of the amount of the optic 42
exposed as the iris of the varies in size). For example, diameter
of the central zone 48 may be at least about 2-millimeters.
Alternatively, the diameter of the central zone 48 may be greater
than 3 millimeters or greater than 4 millimeters. In some
embodiments, the outer diameter of the surrounding zone is greater
than about 4 millimeters, preferably greater than or equal to 5
millimeters or greater than or equal to 6 millimeters. In certain
embodiments, the optic 42 comprises one or more additional zones
surrounding the zones 48, 50, for example, to further adjust the
mixture of near, distant, and/or intermediate vision as a function
of lighting conditions. In some embodiments, the optic 42 further
comprises an intermediate or transition zone disposed between the
central and surrounding zones 48, 50 that is configured, for
example, to preclude discontinuities between the zones 48, 50 that
could produce glare or other unwanted optic effects.
[0073] In some embodiments, the central zone 48 and/or the
surrounding zone 50 has at least one surface 45, 46 that is
aspheric and/or toric in shape and that may be configured to
correct or enhance an aberration of the eye (e.g., astigmatism,
spherical aberrations, coma, and the like). The aspheric or toric
shape and associated correction may be present when the intraocular
lens 40 is in the accommodative configuration, the disaccommodative
configuration, or both the accommodative and disaccommodative
configurations. For radially asymmetric configurations (e.g.
toric), the toric shape may be oriented along any axis
perpendicular to the optical axis, and preferably aligned to reduce
the natural astigmatism in the eye. Alternatively the optic may be
aligned to enhance or induce astigmatism, e.g., a vertical or
horizontal astigmatism, in order to increase depth of focus. The
central zone 48 and/or the surrounding zone 50 may comprises a
diffractive grating or phase plate that is configured to increase
or decrease the optical power of the one zone as compared to the
remaining zone (which may also include a diffractive zone or
grating having a different power). In some embodiments, the
diffractive grating or phase plate may be configured to correct for
or enhance a chromatic aberration.
[0074] The optic 42 and the haptic 44 may be integrally made of a
single material with or without different characteristics.
Alternatively, the optic 42 may be made of material from one family
and the haptic 44 may be made of material from another family
(e.g., one from an acrylic family member and the other from a
silicone family member). One or both of the optic 42 and the haptic
44 may be made of a hydrophilic material. In some embodiments, the
intraocular lens 40 is fabricated such that the optic 42 is
stressed by the haptic 44 when the intraocular lens 40 is in a
natural state in which there are no external forces acting on the
intraocular lens 40. Examples of this type of pre-stressing of an
optic are discussed in co-pending U.S. patent application Ser. No.
11/618,411, which is herein incorporated by reference. Other haptic
configurations may be incorporated into embodiments of the present
invention such as, for examples, those discussed in co-pending U.S.
patent application Ser. No. 11/618,325, which is herein
incorporated by reference.
[0075] The optic 42 may be made from a relatively soft material and
configured so that at least a portion of the optic 42 distorts or
changes shape readily under the limited deforming force initiated
by the ciliary muscle and/or capsular bag and transmitted through
the haptic 44. An exemplary material is a relatively soft silicone
material, although other suitable materials may be used as well.
The stiffness of the optic 42 may be less than 500 kPa, or
preferably may be between 0.5 kPa and 500 kPa, or more preferably
may be between 10 kPa and 200 kPa, or even more preferably may be
between 10 kPa and 50 kPa or between 25 kPa and 50 kPa. In contrast
with the optic 42, the haptic 44 may be made from a relatively
stiff material, so that it can efficiently transmit the deforming
forces from the capsular bag to the optic 42. As discussed below,
various modified embodiments provide different force transfer
capacity in different portions of a haptic, an optic, or both a
haptic and an optic. An exemplary material is a relatively stiff
silicone material, although other suitable materials may be used as
well, such as acrylic, polystyrene, or clear polyurethanes. The
haptic 44 may preferably be stiffer than the optic 42. The
stiffness of the haptic 44 may be greater than 500 kPa, or
preferably may be greater than 3000 kPa.
[0076] Various types of materials, haptic configurations, and/or
optic configurations may be utilized to provide a predetermined
amount of optic distortion or shape change in response to an ocular
force, either to the optic 42 or to any other optic embodiment
discussed or suggested herein. Examples of such materials and
mechanisms for providing a desired amount of optic shape change or
distortion due to ocular forces may be found in U.S. Pat. No.
7,125,422 and in U.S. Patent Application Numbers 2004/0082993,
2004/0111153, and 2005/0131535), all of which are herein
incorporated by reference in their entirety. As an example, the
optic 42 may comprise an optic body and a liquid or gel material
disposed within a void of the optic body. Such an optic structure
may be configured to both provide a low optic stiffness and to
maintain an overall optic shape that is suitable for vision.
[0077] In certain embodiments, as seen in FIG. 8, a method 100 of
implanting an intraocular lens and providing accommodative vision
to a subject comprises an operational block 110 of providing the
intraocular lens 40 having a central zone 48 and a surrounding zone
50. The method also comprises an operational block 120 of placing
the intraocular lens 40 into the eye of a subject in a
disaccommodated configuration in which the central zone has a base
optical power. The method 100 further comprise an operational block
130 of adjusting or causing the intraocular lens to have an
accommodated state within the eye in response to ciliary muscle
contraction, wherein the central zone 48 has an add optical power
that is at least 1 Diopter greater than the base optical power,
preferably 2 Diopters greater than the base optical power, and even
more preferably 3 to 4 Diopters greater than the base optical
power. In some embodiments, the central zone 48 and the surrounding
zone 50 simultaneously have different optical powers when the optic
42 is in the accommodated configuration and/or when the optic 42 is
in the disaccommodative configuration. In some embodiments, the
method is comprised of placing the intraocular lens 40 into the eye
of a subject in an accommodated configuration wherein the central
zone 48 has an add optical power that is at least 1 Diopter greater
than the base optical power, preferably 2 Diopters greater than the
base optical power, and even more preferably 3 to 4 Diopters
greater than the base optical power.
[0078] The method 100 is generally used in conjunction with an
intraocular lens having a disaccommodative bias. For example, the
intraocular lens 42 may be configured to have a disaccommodative
bias such that the surrounding zone 40 has an optical power that is
selected to provide distant vision when the intraocular lens 40 is
in a natural configuration in which there are no external forces on
the haptic 44. Thus, when the intraocular lens 40 is placed into
the eye 10, it has a relatively elongate shape in a direction that
is perpendicular to the optical axis OA, as illustrated in FIG.
6.
[0079] In operational block 130, the intraocular lens is adjusted
to have an accommodative configuration as an ocular force F
(illustrated in FIG. 7A) radially pushes the haptic 44 toward the
optical axis OA. This places the intraocular lens 40 in a stressed
state or configuration so that the adjustable optic 42 deforms
and/or thickens into a more oval shape that will increase the
optical power of the central zone 48 and optionally increase the
optical power of the surrounding zone 50. The ocular force F is
typically within a range of at least about 1 gram to about 10
grams. Within the art, an understanding of the physiology of the
eye is still developing. Thus, the range of ocular forces able to
provide the above ranges of relative and/or absolute thickness
change are anticipated as the physiology of the eye is better
understood. Such ranges of ocular forces are also consistent with
embodiments disclosed herein.
[0080] The intraocular lens 40 may be placed in the capsular bag 18
of the eye 10, such that an outer periphery 54 of the haptic 44 is
in contact with an equatorial region of the capsular bag 18. In
such embodiments, a contraction of the ciliary muscle 25 causes the
capsular bag 18 to produce the ocular force F, causing the
intraocular lens 40 to be actuated into the accommodating
configuration. Alternatively, the intraocular lens 40 may be
configured for placement in another portion of the eye 10. For
example, the intraocular lens 40 may be configured for placement
such that the haptic 44 is in direct contact with the ciliary
muscle 25 or even the zonules 26.
[0081] B. Accommodating Intraocular Lenses With Inner Arcuate
Members
[0082] FIGS. 9-15 show various embodiments of intraocular lenses
having haptics that include a member, which can be an arcuate
member such as a ring or a plurality of ring segments, disposed
inside of an optic. These embodiments can be arranged in a
generally planar configuration as described in connection with
FIGS. 9-12 or in a higher volume configuration, sometimes referred
to herein as a bag-filling arrangement, as in FIGS. 13-15.
[0083] 1. Generally Planar Configurations
[0084] Referring to FIGS. 9-12, an intraocular lens 240 comprising
an adjustable optic 242 and a haptic 244 may be configured to have
a disaccommodative bias when placed into the eye 10. The optic 242
includes a central zone 248 and a surrounding zone 250 that are
similar to the zones 48, 50, respectively. The intraocular lens 240
is similar to the intraocular lens 40 with at least the exception
that it includes an inner ring 246. At least a portion of the inner
ring 246 is transparent and has a transmissivity of at least 80%,
preferably at least 90% or even 95% or greater. The haptic 244
further comprises a plurality of arms 252 that connect the inner
ring 246 with the peripheral portion 251. In the illustrated
embodiment, there are eight arms 252; however, more or fewer arms
may be used (e.g., 4 arms or 16 arms).
[0085] The inner ring 246 is configured to deform an optic 242 in
response to an ocular force acting on a peripheral portion 251 of
the haptic 244. The inner ring 246 is shown in the form of a
contiguous ring in FIGS. 9 and 11. Alternatively, the inner ring
246 may be in the form of a broken ring with radial voids between
ring segments, for example, with a radial void disposed between
each of the arms 252. The peripheral portion 251 may be in the form
of a continuous ring, as shown in the illustrated embodiment, or in
the form of a broken ring. Either or both rings 246, 251 may have
shapes that are not circular and may be shaped to distribute an
ocular force about the optic 242 in a predetermined manner.
[0086] Various modified embodiments below are provided in which an
arcuate member similar to the ring 246 is adapted to apply a
non-uniform force to an optic to induce asymmetrical forces applied
to an optic to produced an optical performance characteristic.
[0087] The arms 252 may include void portions 254 configured to
reduce the mass of the intraocular lens 240 and the haptic 244.
Such reduction in mass may be utilized to allow the ocular force F
to be more completely transmitted to the inner ring 246 and optic
242. The void portions may be triangular in shape, as illustrated
in FIGS. 9 and 11, or may have some other shape (e.g., circular or
rectangular) that may be selected to provide a desired mass
reduction and/or distribution of forces on the inner ring 246
and/or adjustable optic 242.
[0088] The thickness along the optical axis OA of inner ring 246
(and/or of portions of the haptic 244 disposed within the
adjustable optic 242) may be selected to control the amount and/or
distribution of an ocular force acting on the intraocular lens 240.
For example, in some embodiments, the performance (e.g., the change
Diopter power of the intraocular lens 240 between accommodative and
disaccommodative configurations) increases as the edge thickness
increases. In such embodiments, other design constraints (e.g.,
optical performance or physical constraints of the eye) may,
however, place an upper limit on the maximum optic edge thickness.
In some embodiments, the ring portion 246 of the haptic 244 has a
maximum axial thickness that is at least one half a maximum axial
thickness of the central zone, as illustrated in FIG. 10. In other
embodiments, the ring portion 246 of the haptic 244 has a maximum
axial thickness that is at least 75% of a maximum axial thickness
of the central zone. These and other predetermined relationships
between axial thicknesses of the protruding portions of the haptic
244 and the axial thicknesses of the optic 242 may also be
advantageously applied to other embodiments of the invention
discussed or suggested herein. For example, the thickness of the
haptic arms may be selected to control the amount and/or
distribution of an ocular force acting on the optic 242. Also,
where applicable, any of the features, limits, and so forth
disclosed with regard to the intraocular lens 40 may also be
applied to the intraocular lens 240.
[0089] 2. Bag Filling Configurations
[0090] Referring to FIGS. 13-15, an intraocular lens 340 comprising
an adjustable optic 342 and a haptic 344 may be configured to have
an accommodative bias when placed into the eye 10. The optic 342
includes a central zone 348 and a surrounding zone 350 that are
similar to the zones 48, 50, respectively, of the previous
embodiment. The haptic 344 comprises a plurality of arms connected
together at their distal ends by an external ring 360 and at their
proximal ends by an inner ring 362 disposed within the optic 342.
In the illustrated embodiment, there are eight arms; however, more
or fewer arms may be used. Similar to the intraocular lens 240, at
least a portion of the ring 362 is transparent and has a
transmissivity of at least about 80%, preferably at least 90% or
even 95% or greater. Preferably, the refractive index of the inner
ring is substantially equal to the refractive index of the
adjustable optic 342.
[0091] The outer surface of the haptic 344 is configured to contact
a relatively larger region of a capsular bag 18, for example, a
region that extends beyond an equatorial region of the capsular bag
18. In the illustrated embodiment, the haptic comprises an outer
surface 364 that is configured to conform to at least one of the
anterior and posterior capsules of a capsular bag into which the
intraocular lens is placed. The relatively large surface area of
the outer surface 364 of the haptic 344 may be utilized to provide
increased adhesion between the capsular bag and the intraocular
lens 340.
[0092] Because of this increased adhesion, the intraocular lens 340
may be better suited for use as an accommodatively biased
intraocular lens or other configurations where the intraocular lens
is pulled outwardly by the capsular bag. In certain embodiments, a
method implanting the intraocular lens 340 and providing
accommodative vision is similar to that of the method 100, except
that the intraocular lens 340 is placed into the eye in an
accommodated configuration and adjusted to a disaccommodative
configuration by using the walls of a capsular bag to pull radially
outward on the inner ring 362 and the adjustable optic 342. Where
applicable, any of the features, limits, and so forth disclosed
with regard to the intraocular lenses 40, 240 may also be applied
to the intraocular lens 340.
II. Intraocular Lenses with Enhanced Performance Through Asymmetric
Loading
[0093] As discussed above, generally symmetric haptics can be used
to provide accommodation and multiple foci. Further enhancement of
performance can be obtained by asymmetric loading of an optic.
Asymmetric loading can enhance performance by increasing the add
power between unstressed and stressed states, compensate for
aberrations due to asymmetry in the patient's anatomy, and/or
exploit optical asymmetry to improve visual acuity.
[0094] A. Accommodating Intraocular Lenses Having Increased Add
Power
[0095] FIGS. 16-22 illustrate further embodiments in which ocular
force is concentrated in a particular region to enhance the add
power in that region.
[0096] FIG. 16 shows an intraocular lens 400 having an optic 404
and a haptic 408. The optic 404 focuses light on the retina when
disposed in the eye 10. In one embodiment, the intraocular lens 400
has an unstressed configuration and a stressed configuration. In
the stressed configuration, ocular forces are transferred to the
optic 404 asymmetrically through the haptic 408. Asymmetric force
transfer can cause asymmetric deformation of the optic 404.
Asymmetric deformation can produce a plurality of optical powers
and/or aberrations, as discussed below.
[0097] In one variation, the optic 404 has a first zone 412 and a
second zone 416 in the stressed configuration where the first zone
412 provides a distance vision power and the second zone 416
provides a near vision power. The near vision power is greater than
the distance vision power. In one embodiment, the first zone 412
and the second zone 416 both have a distance vision power in the
unstressed configuration. The intraocular lens 400 can be
configured so that the first and second zones 412, 416 provide the
same power in the unstressed state.
[0098] The second zone 416 preferably is an adjustable zone that
can be adjusted through a range of optical powers when in a
stressed state, e.g., subjected to a compressive ocular force. A
maximum power of the second zone 416 when in a stressed state is
greater than the distance vision power in first zone 412 when the
optic is in the unstressed state. In some embodiments, the range of
powers includes a near vision power, e.g., a power sufficient to
bring into focus on the retina objects within 12 to 24 inches from
the eye. The power of the first zone 412 in a stressed state can be
the same as in the unstressed state or can vary in a range greater
than the distance vision power.
[0099] FIG. 17 shows that a central optical axis A.sub.c of the
intraocular lens 400 intersects the first zone 412. The second zone
416 is adjacent the first zone 412 and off-set from the axis
A.sub.c. In some embodiments, the second zone 416 is smaller than
the first zone 412, although other embodiments include a second
zone that is similar in size to the first zone. The second zone 416
can be disposed in a region covering less than one-half of the
surface area of the optic 404. In one embodiment, the second zone
416 has an arcuate or semi-circular configuration with a radial
width R.sub.3 less than a radius R.sub.1 of the optic 404. The
innermost edge of the radial span of the second zone 416 can be
off-set form the center of the radius R.sub.1 by a distance
R.sub.2. Preferably the innermost edge of the radial span of the
second zone 416 is spaced from the center of the radius R.sub.1 by
an amount sufficient to permit the vision system of the patient to
select between the regions 412, 416 depending on the position of
the object to be viewed. The innermost edge of the radial span of
the second zone 416 can be spaced apart from the location of the
center of radius R.sub.1 by at least about 30 percent of the
diameter of the optic 404. In other embodiments, the second zone
416 extends up to a diameter of the optic 404 but may have a zone
of greatest flexibility that is spaced radially from the diameter
of the optic 404. In another embodiment, the first zone and second
zone may be symmetrical arcuate segments which may be advantageous
for a toric lens design.
[0100] FIG. 19A shows that the intraocular lens 400 is adapted to
respond to ocular forces to adjust the power of the second zone 416
toward the near vision power. In particular, the solid line
illustrates the power across the optic 404 in an unstressed state.
As shown, the first zone 412 (between 0 and R.sub.1) and the second
zone 416 (between R.sub.2 and R.sub.3) each have distance vision
power in the unstressed state. The dashed line shows that the first
zone 412 (between 0 and R.sub.1) has distance vision power and the
second zone 416 (between R.sub.2 and R.sub.3) has near vision power
in the stressed state. The difference between the power of the
second zone 416 in the stressed state and the first zone 412 in the
unstressed state can be 2 Diopters or more. In some embodiments,
this difference, i.e., the "add power", can be 2-4 Diopters. In
some embodiments, the add power can be 5 Diopters or more.
[0101] In one approach, the intraocular lens 400 is configured such
that, when implanted in the patient, the second zone 416 is located
below the first zone 412. For example, a particular diameter of the
optic 404 is selected to be placed generally in the eye and the
second zone 416 is below that diameter. In this context the terms
"horizontally disposed" and "below" refers to the orientation when
where the patient is upright.
[0102] The additional power of the second zone 416 results from a
change in shape of the optic 404, e.g., of the second zone 416. The
shape change is the result of asymmetric transfer of ocular force
through the lens 400. Asymmetric force transfer is generally
achieved through various configurations of the haptic 408, but
could also be due to the configuration of the optic 404 as
discussed below. In some embodiments, the haptic 408 also changes
the shape of the first zone 412 but by a lesser amount than the
second zone 416. In other embodiments, the ocular forces are
asymmetrically applied to the optic to cause maximum add power in
the first zone 412 and a lesser add power in the second zone 416,
as discussed below.
[0103] In the embodiment of FIG. 16-19, the haptic 408 includes
outer and inner members 432, 436. One or more of the inner and
outer members 432, 436 can be annular, e.g., including rings or
ring segments. The outer and inner members 432, 436 can be coupled
together by a radially extending structure, such as by a plurality
of arms 460 as discussed above. One technique for transferring
force asymmetrically through the haptic 408 is through the
configuration of the inner member 436. The inner member 436 can be
adapted to asymmetrically transfer forces from the outer periphery
of the haptic 408 to the optic 404. The inner member 436 can be
configured to transfer more ocular force to a zone of the optic 404
for a desired optical effect. For example, the inner annular member
436 can be configured to act on a portion of the second zone 416 to
cause the optical power of the zone 416 to vary through a range, as
discussed above.
[0104] The inner member 436 can include a flexible portion 438
disposed adjacent to or inside at least the second zone 416 of the
optic 404. In one variation the flexible portion 438 borders (e.g.,
at least partially surrounds) the second zone 416. The inner member
436 also includes a stiff portion 440 that is disposed adjacent to
or inside the first zone 412. In one variation the stiff portion
440 at least partially surrounds (e.g., borders) the first zone
412. The flexible portion 438 can be made more flexible than the
stiff portion 440 by manipulating the material properties.
[0105] For example, the material properties in the stiff and
flexible portions 438, 440 can be different, e.g., higher modulus
in the flexible region 438 and lower modulus in the stiff region
440. Techniques for varying modulus of a material are discussed in
U.S. Publication No. 2009-0163602, which is incorporated by
reference in its entirety. The portion 438 can be made flexible by
mechanical techniques, such as perforating or segmenting the
portion 438. Other techniques for increasing or decreasing the
stiffness of the stiff or flexible portions 438, 440 include
changing the thickness. In one embodiment, the enhanced thickness
is measured in a radial direction, e.g., perpendicular to the axis
A.sub.c. In one embodiment, the enhanced thickness is measured in a
direction parallel to the axis A.sub.c.
[0106] In one embodiment, the flexible portion 438 of the inner
annular member 436 includes a ring segment subtending an arc of
about 180 degrees between a first end 442 and a second end 444. In
the embodiment of FIGS. 16-19, the first and second ends 442, 444
are connected by a transverse member 448 that extends across the
optic 404. In one embodiment, both the flexible portion 438 and the
transverse member 448 of the haptic 408 are disposed inside the
optic 404. The transverse member 448 can be disposed between the
first zone 412 and the second zone 416. In other embodiments, the
first zone 412 and the second zone 416 are adjacent with no
transverse member between them.
[0107] The arms 460 include distal ends 464 coupled with the outer
member 432, proximal ends 468 coupled with the inner member 436,
and a length extending therebetween. FIGS. 18 illustrate that the
arms 460 can all have the same configuration. In addition, the arms
460 can be symmetrically disposed about the axis A.sub.c. In other
embodiments, the arms may be asymmetrically disposed about the axis
A.sub.c in order to provide asymmetric forces on the optic. The
inner and outer annular member 432, 436 are symmetric or asymmetric
around the axis A.sub.c.
[0108] FIG. 16A shows that the haptic 408 and the intraocular lens
400 have a substantially planar structure. For example, in one
embodiment a plane extending through the outer member 432 and
oriented perpendicular to the axis A.sub.c intersects the optic
404. In another embodiment, a plane extending through the outer
member 432 and perpendicular to the axis A.sub.c intersects the
inner member 436 and the optic 404. In another embodiment, a plane
extending through a mid-point of the outer member 432 also extends
through a mid-point of the inner annular member 436. In this
context, the "mid-point" is measured in a direction parallel to the
axis A.sub.c.
[0109] Configuring the intraocular lens 400 in a generally planar
arrangement has several advantages. First, if the intraocular lens
400 is placed in a capsular bag, the ocular forces are generally
applied inwardly toward the axis A.sub.c and/or outwardly away from
the axis A.sub.c, e.g., along a plane perpendicular to the axis
A.sub.c and intersecting the equator of the capsular bag. By
placing the annular member 432 at the equator, and the arms 460 in
the plane along which the ocular forces act, the intraocular lens
maximizes compression of the optic 404. The in-plane transfer of
forces through the arms 460 to the optic minimizes torque and
maximizes deformation force to a portion of the optic 404, e.g., to
the second zone 416.
[0110] In other embodiment similar to that of FIGS. 13-15, a plane
perpendicular to the axis A.sub.c and intersecting the annular
member 432 is disposed anterior to a plane perpendicular to the
axis A.sub.c and intersecting the annular member 436. In such
embodiments, the haptic 408 fills the evacuated capsular bag to a
greater extent. Bag filling arrangements can be advantageous in
some cases. For example, these arrangements prevent or
substantially reduce a shrink-wrap effect that can occur in an
evacuated capsular bag, which could result in compressive force
being applied to the optic 404 along the direction of the axis
A.sub.c. Such forces could impede deformation of the optic 404.
Also, if the haptic has a bag filling configuration, the surface
area of contact between the haptic and the interior of the capsular
bag is greater, e.g., because the surface area of the arms that
engages the bag interior is greater. FIGS. 13-14 show, for example,
that haptics with a bag filling arrangement extend radially
outwardly to an outer surface configured to engage the capsular bag
and anteriorly from this surface to a location anterior of the
equator. Further, the annular member 432 can be configured to
engage a posterior facing inside surface of an anterior aspect of
the capsular bag, which can move in response to ocular forces on
the capsular bag. Relative movement between the capsular bag and
the annular member 432 can create a fulcrum effect, increasing the
force applied to the optic 404. In bag filling variations, the
annular member 432 need not be larger than the annular member 436.
For example, the annular member 432 need not be partially or
entirely located farther from the axis A.sub.c than is the annular
member 436. Also, the annular member 432 could be disposed
proximally of the optic 404. In this arrangement, the annular
member 432 would be configured to engage an anterior facing inside
surface of a posterior aspect of the capsular bag. This arrangement
could be advantageous in biasing the optic forward of the posterior
aspect of the capsular bag to reduce the chance of subluxation. The
annular member 432 could be configured with distinct edges that
impede posterior capsule opacification.
[0111] In one embodiment, the haptic 408 includes eight arms 460
that extend between the inner and outer members 436, 432. The
arrangement of the arms 460 and the inner and outer members 432,
436 can vary. FIG. 16 shows that three of the arms are coupled with
the flexible portion 438 of the inner annular member 436 and three
of the arms 460 are coupled with the stiff portion 440 of the inner
annular member 436. Two of the arms 460 are coupled with both the
stiff and flexible portions 438, 440. In order to increase the
amount of force into any zone, the thickness of the arm 460 and/or
material flexibility may be manipulated. Additionally, the
thickness and/or material flexibility of any circumferential or
surrounding member extending between arms (e.g., rings) may be
changed in order to change the force applied to the optic. In other
embodiments, the number of arms protruding into a particular zone
may be varied in order to vary the force applied to the optic.
[0112] In one embodiment, the transverse member 448 and the
flexible portion 438 of the inner member 436 surround the second
zone 416. The area of the optic 404 that corresponds to the second
zone 416 is smaller than the area of the first zone 412. In one
embodiment, the second zone 416 is less than half of the surface
area of the first zone 412. The first zone 412 may be fixed power
or responsive to ocular forces to increase its power. A greater
change in power results in the second zone 416 than in the first
zone 412 because the area to be deformed in the second zone 416 is
smaller, which results in higher pressure in the second zone 416
for a comparable force. This in conjunction with the flexible
portion 438 allows for greater deformation and power change in the
second zone 416. The second zone 416 may also be designed to result
in little or now deformation if a stiff material (along with
thicker design) prevents the second zone from transferring force.
In such an embodiment, the first zone 412 may be comprised of a
more flexible material such that the first zone 412 results in an
increase in power due to deformation.
[0113] In some variations, the transverse member 448 is disposed
inside a portion of the optic that does not change shape or power,
but rather substantially retains the power of the first zone 412.
FIG. 19A illustrates this feature in that the power between R.sub.1
and R.sub.2 in the stressed state (dashed line) is the same as in
the unstressed state (solid line).
[0114] FIG. 19B illustrates the optical behavior of another
arrangement in which the first zone 412 is more responsive to
ocular forces than the second zone 416. By reducing the volume of
material of portion 440, less ocular force is absorbed in
deformation of the portion 440 and more of the force is available
to deform the optic. In effect, the more flexible portion 440 may
more efficiently transfers ocular force to the first zone 412 than
is transferred by the stiff portion 438 to the second zone 416.
Also, reinforcing a portion of the inner annular member 436
bordering the second zone 416 may isolate the second zone 416 from
ocular forces transferred through the haptic 408. In such an
arrangement, the first zone 412 will be more responsive to ocular
forces to deform more, inducing a greater power add than the in the
second zone 416.
[0115] The outer member 432 includes a continuous structure that
entirely surrounds the optic 404. The outer member 432 is
configured to engage or be disposed in an ocular structure, such as
the capsular bag as discussed above. For example, the outer member
432 can be configured to be placed against an interior aspect of an
evacuated capsular bag at the equator of the bag. In other
embodiments, the outer member 432 is configured to be inserted into
an intraocular lens holder, such as any of those described in U.S.
Pat. No. 6,797,004 and in U.S. Publication No. 2010-0094415, both
of which are incorporated by reference in their entireties.
[0116] FIG. 18 shows that in one embodiment, the outer member 432
is a ring having an inner radius, an outer radius, and a radial
thickness that is substantially constant therearound. In modified
embodiments, the outer member 432 can include non-circular rings,
oval or wavy structures, and/or a plurality of substantially
straight segments. The outer member 432 also need not be continuous
but rather can include a plurality of arcuate or linear segments
with circumferential gaps therebetween.
[0117] FIG. 20 illustrates an intraocular lens 500 similar to the
lens 400, having a first zone 512 and a second zone 516 but where
an outer member 532 thereof has a non-uniform force transfer
configuration. The non-uniform force transfer configuration enables
a haptic 508 of which the outer member 532 is a part to apply
forces asymmetrically to an optic 504 of the lens 500. In some
embodiments, the haptic 508 includes an inner member 536. In other
embodiments, the haptic 508 can include cantilevered arms as in the
embodiment of FIGS. 3-5. Non-uniform force transfer from the outer
member 532 can induce different amounts of power add in different
areas of the optic 504 to provide the benefits described
herein.
[0118] The outer member 532 includes a non-uniform ring with a
first portion 532a disposed about a distance power region and a
second portion 532b disposed around a near power region. The first
portion 532a is less stiff than the second portion 532b, such as by
having less radial thickness. Other techniques discussed herein to
make the first portion 532a less stiff than the second portion 532b
could also employed in connection with the lens 500. By being
stiffer, the second portion 532b is able to transfer more ocular
force to the optic 504 than is transferred by the first portion
532a, producing a greater increase in the second zone 516 than
would be provided in an intraocular lens having a constant
stiffness outer member 532.
[0119] In variations of any of the intraocular lenses disclosed
herein, the optic can comprise at least three zones. The zones can
include zones similar to the first and second zones discussed above
and a third zone having a range of powers greater than the distance
vision power. The range of powers in the third zone can include an
intermediate power, which is a maximum power that is less than the
near vision power. In one arrangement, the outer member 532 is
configured to induce at least the intermediate power in the third
zone and the near vision power in the second zone. Such an
arrangement may have the second zone with near vision as a
concentric annular ring surrounding the optical axis. The third
zone for intermediate vision may concentrically surround the first
zone. The first zone with distance vision would lie outside and
concentrically surround the third zone.
[0120] FIG. 18 shows that the arms 460 can be symmetrical, though
other embodiments can have asymmetric configurations. The distal
ends 464 of the arms have a forked configuration with two tapered
legs 480 extending proximally to a waist portion 482. A void space
484 is disposed between the legs 480 and a segment of the outer
member 432. The arms 460 are tapered from a waist portion 482
toward the inner member 436. The circumferential length of the
proximal end 468 of each of the arms 460 is less than the
circumferential length of the segment of the outer member 436
extending between the distal ends of the legs 480.
[0121] The complex geometry of the arms 460 provides a number of
structural features that can be varied about the circumference of
the haptic 408 to provide asymmetric force transfer capability
about the optic 404 to provide accommodative compensation
performance as desired. For example, the length and/or thickness of
the arms 460 may be manipulated to vary the force provided to the
optic 404.
[0122] FIG. 21 illustrates an intraocular lens 700 that is similar
to those hereinbefore described except as discussed below. The
intraocular lens 700 includes an optic 704 and a haptic 708. The
optic 704 has a fixed power region 712 and an add power region 716.
The add power region 716 is flexible or deformable so that is power
can be varied, as discussed above, at least up to a power
sufficient for near vision.
[0123] The haptic 708 includes a stiff portion 718 configured to be
disposed inside the fixed power region 712 and a deformable portion
720 configured to be disposed inside the add power region 716 of
the optic 704. The stiff portion 718 can take any suitable form but
preferably includes a rigid member, such as a rigid disk, that can
be disposed within the fixed power region 712. The stiff portion
718 can include a substantially continuous solid member. The stiff
portion 718 and the fixed power region 712 extend between a
periphery of the optic 704 and a central zone of the optic. The
fixed power region 712 covers a semi-circular portion of the optic
704 in the embodiment of FIG. 21.
[0124] The stiff portion 718 is coupled with the proximal ends of a
plurality of arms 728a extending radially away from an outer
periphery of the stiff portion 718 toward an outer periphery of the
intraocular lens. An outer member 732 can be disposed at the outer
periphery. The stiff portion 718 extends between proximal ends of
at least some of the arms 728a.
[0125] The stiff portion 718 can be entirely encapsulated within
the optic 704. In some embodiments, the stiff portion 718 is
disposed beneath at least one of an anterior surface and a
posterior surface of the optic 704 and thus may be referred to
herein as a sublayer. The outer periphery of the stiff portion 718
is disposed closer to a central optical axis A.sub.c than is the
outer periphery of the optic 704. In one embodiment, the stiff
portion 718 has a posterior surface disposed anterior of the
posterior surface of the optic 704. Also, the anterior surface of
the stiff portion 718 can be disposed posterior of the anterior
surface of the optic 704. The stiff portion 718 is configured to
limit, e.g., substantially prevent, deformation of the optic 704 in
the fixed power region 712.
[0126] The deformable portion 720 of the haptic 708 includes an
inner member 740 and an intermediate member 744 disposed between
the inner member and the outer periphery 732. The inner and
intermediate members 740, 744 can be arcuate members, e.g., ring
shaped. In one embodiment, the inner member 740 includes at least
one ring segment disposed between adjacent arms 728b and at least
one ring segment extending between an arm 728b and the stiff
portion 718. The inner member 740 can comprise a plurality of ring
segments connecting a plurality of arms 728b at their proximal
ends. The inner member 740 can comprise a plurality of ring
segments connecting a plurality of arms 728b to the stiff portion
718.
[0127] An inner add power region 752 is disposed between the inner
arcuate member 740 and the fixed power region 712. The deformable
portion 720 is adapted to increase the power of the add power
region 752 by transferring ocular forces applied to the outer
periphery 720 to the add power region.
[0128] In one embodiment an outer add power region 756 is defined
between the inner add power region 752 and the intermediate arcuate
member 744. The outer add power region is an annular segment
extending circumferentially from a first end adjacent to the fixed
power region 712 on one side of the optic 704 to a second adjacent
to the fixed power region 712 on an opposite side of the optic 704.
The outer add power region 756 can include one or a plurality of
regions defined between the members 740, 744 and the arms 728b. The
outer add power region 756 also can include one or a plurality of
regions defined between the arcuate member 740, 744, one of the
arms 728b, and an edge of the stiff portion 718.
[0129] The intermediate arcuate member 744 transfers a portion of
the ocular force to the outer add power region 756 producing an add
power. The add power of the outer add power region can be a
different power from that of the inner add power region 752. In
particular, the outer add power region 756 can provide an
intermediate power zone giving the patient the ability to select
between viewing intermediate objects and near objects without
changing the accommodated state of the intraocular lens 700.
[0130] The gaps between the arms 728b, the arcuate member 740, 744,
and the stiff portion 718 can be filled with a deformable material.
The material can be the same as or different than the material
disposed over the stiff portion 718 of the haptic 708. For example,
a suitable gel can be disposed in these regions. A suitable gel is
one that maintains an optical surface but is deformable under the
loads applied by the eye and transferred through the deformable
portion 720 of the haptic 708. Suitable gels include hydrophilic
based and silicone based gels.
[0131] FIG. 22 illustrates another intraocular lens 800 that is
similar to that of FIG. 21 except as set forth below. The lens 800
includes an optic 804 and a haptic 808. More than half of the optic
804 comprises a fixed power region 812 and less than half of the
optic comprises an adjustable add power region 816. In one
variation, the add power region 816 is disposed within an arcuate
member 820. The add power region 816 can comprise a portion of the
optic 804 where deformation is concentrated to enhance the add
power of the optic 804. The add power region 816 can be
semi-circular with a radius that is less than the radius of the
optic 804. The add power region 816 can have a geometric center
that is off-set from the geometric center of the optic 804.
[0132] A peripheral area 824 surrounding one side of the add power
region 816 can be configured to have negligible change in shape and
power, for example matching the shape and power of the fixed power
region 812.
[0133] In the embodiments of FIGS. 21-22, the arms coupled with the
more deformable portion of the respective haptic are longer. The
arms in these portions extend further into their respective optics
to position the application of force closer to the zone to be
modified to the higher power. This feature, in addition to being
coupled with a more flexible haptic construction, enables these
embodiments to enhanced add power of the intraocular lenses.
[0134] B. Intraocular Lenses Having Asymmetric Force Transfer
[0135] The intraocular lenses discussed below are configured to
correct for a patient's asymmetric optical aberrations and
optionally provide accommodation.
[0136] Forces in the eye, such as within the capsular bag as
applied by the ciliary muscles, are believed to be symmetric about
the equator of the capsular bag. Asymmetric aberrations can be
treated by configuring an intraocular lens to transfer these
symmetric ocular forces asymmetrically to an optic or by
configuring an optic to respond asymmetrically to a uniform force.
These configurations can create or increase asymmetry of an optical
surface in a stressed or unstressed state to decrease an asymmetric
aberration. These configurations can induce, increase, or decrease
the asymmetry of an asymmetric optical surface in a stressed or
unstressed state to provide or eliminate an extended depth of focus
in one of these states.
[0137] If the forces around the capsular bag are not uniform,
asymmetric transfer of force within the intraocular lens can
provide some of the same advantages or can be used to compensate
for force asymmetry in the patient's anatomy.
[0138] Among the asymmetric effects that can be induced in the
intraocular lens or optic are differential bending along different
axes or chords of the optic. In general asymmetric bending can be
provided by varying mechanical properties of the haptic, the optic,
or both the haptic and optic asymmetrically.
[0139] FIG. 23A shows an intraocular lens 1000a including an optic
1004 and a haptic 1008. The optic 1004 is adapted to be deformed
when subjected to a compressive ocular force transferred through
the haptic 1008a. The haptic 1008a is adapted to apply different
forces to different portions of the optic 1004 in response to a
uniform annular compressive ocular force, e.g., as applied by the
ciliary muscles through the capsular bag. The haptic 1008a is
configured to apply a first compressive force to a first portion
1012 of the optic 1004 and a second compressive force to a second
portion 1016 of the optic 1004. The first and second portions 1012,
1016 of the optic 1004 are deformed, e.g., to change power, when
subjected to the compressive ocular force. The intraocular lens may
be configured such that the first portion 1012 of the optic changes
power by a greater amount than more than the second portion
1016.
[0140] In one variation, a first portion of the haptic 1008a
applies more force to the optic 1004 than a second portion of the
haptic 1008a. The haptic 1008a can include a plurality of arms
1020a and 1020b disposed around the optic 1004. In one embodiment,
one or both of a first pair of haptic arms 1020a is configured to
apply a greater force to the optic 1004 than one or both of a
second pair of haptic arms 1020b. Where the pair of haptic arms
1020a is disposed on opposing sides of the optic 1004 along a first
transverse portion 1024 (e.g., a diameter or chord), a change in
curvature along the first transverse portion 1024 due to the
application of a uniform ocular force can be greater than the
change in curvature along a second transverse portion 1028 that
extends between the second pair of haptic arms 1020b. This
configuration produces more change in curvature along the first
transverse portion 1024 than along the second transverse portion
1028 in response to a uniform ocular force. This can be used to
eliminate astigmatism in an eye system (including the intraocular
lens) at least when the optic 1004 is in the deformed state when
the intraocular lens 1000a is properly oriented in the eye. If
astigmatism is more pronounced in distance vision, the intraocular
lens 1000 can be configured to be asymmetric when unstressed and to
deform to a symmetrical configuration by transferring the symmetric
force asymmetrically to the optic 1004, for example by configuring
the pairs of arms 1020a, 1020b to differentially apply force. In
some embodiments, astigmatism may be enhanced to increase depth of
focus.
[0141] FIG. 23B shows that the haptic 1008a can include an inner
member 1032b through which force is applied to a central zone of
the optic 1004. Some embodiments are similar to those of FIGS. 3-5,
having cantilevered arms 1020a, 1020b, which would provide free
ends at the proximal portion of the arms, e.g., ends not connected
to each other by other portions of the haptic.
[0142] A variety of techniques can be used to cause the first pair
of haptic arms 1020a to apply a greater force even when a uniform
compressive force is applied to the intraocular lens 1000a. For
example, the one or more bulk properties of the first pair of
haptic arms 1020a can be different from the bulk properties of the
second pair of haptic arms 1020b. Modulus of elasticity is one
property that relates to the force transfer capability.
Alternatively, the mechanical configuration of the arms can be
modified. The first pair of haptic arms 1020a can be modified by
any suitable technique so that they are more compressible along
their longitudinal axis compared to the second pair of haptic arms
1020b. Or, the second pair of haptic arms 1020b can be made less
flexible. Other mechanical techniques for modifying the force
transfer capability of the haptic arms 1020a and/or 1020b include
modifying the thickness of the haptic arms 1020a and/or 1020b or
pres-stressing the haptic arms 1020a and/or 1020b. In addition, the
haptic arms 1020a and/or 1020b may be curved in order to apply
force to various areas of the optic depending on the type of
asymmetric compression sought.
[0143] FIG. 23B shows an intraocular lens 1000b having a haptic
1008b in which all of the arms have the same force transfer
properties but an inner portion of the haptic is configured to
transfer a non-uniform force to the optic 1004 when the intraocular
lens 1000b is subject to a uniform ocular force.
[0144] The haptic 1008b includes an inner member 1032b that is
coupled with proximal ends of the arms 1020a and 1020b. The inner
member 1032b can be a ring as discussed above. In one variation,
the inner annular member 1032b has a plurality of segments that
respond differently to the application of an ocular (e.g.,
compressive) force. A first pair of segments 1036a of the inner
annular member 1032b can be disposed on opposite sides of the first
transverse portion 1024 and a second pair of segments 1036b can be
disposed on opposite sides of the second transverse portion 1028.
The first pair of segments 1036a can be configured to apply a
greater force to the optic 1004 along the first transverse portion
1024 than is applied along the second transverse portion 1028 by
the second pair of segments 1036b.
[0145] The segments 1036a, 1036b can be portions of a continuous
inner member 1032b as illustrated in FIG. 23B. In other
embodiments, the segments 1036a, 1036b have free ends disposed
circumferentially spaced apart from each other. The segments 1036a,
1036b can be separated from adjacent portions of the inner member
1032b by void spaces, as illustrated in FIG. 23E to enhance the
differential force transfer capability of the segments 1036a,
1036b.
[0146] A variety of techniques can be used to cause the first pair
of segments 1036a to apply a greater force even when a uniform
compressive force is applied to the intraocular lens 1000b as
detailed herein.
[0147] FIG. 23C illustrates another embodiment of an intraocular
lens 1000c that responds asymmetrically to a symmetrical ocular
force. An optic 1004c is provided that is asymmetric in at least
one respect such that is it more responsive to a compressive force
in one portion than in another portion. For example, the optic
1004c can have any combination of undeformed surfaces, such as
spherical or symmetrical in planes containing a central optical
axis A.sub.c, but be asymmetric in a plane perpendicular to the
axis A.sub.c. In particular, the optic 1004c can be oval or other
non-symmetrical shape in a plan transverse to the axis A.sub.c. If
the bulk material properties do not vary within the optic 1004c,
the oval shape is more compressible along the minor axis B than
along the major axis A because the distance from the application of
force to the center of the optic is less than it is along the major
axis A. This arrangement can create address asymmetric aberrations,
such as by creating or eliminating an astigmatic effect.
[0148] FIG. 23C shows that a haptic 1008c coupled with the optic
1004c may incorporate arms 1020c of different lengths in order to
couple with the periphery of the optic 1004c. In one embodiment,
the different length of the arms 1020c enables the haptic 1008c to
maintain a generally circular outer member 1032 while the optic is
oval shaped or elongated in at least one axis. Although the arms
1020c are shown coupling generally to the peripheral side surface
of the optic 1004c, this disclosure also contemplates that the arms
1020c could protrude into the optic 1004c as in the embodiment of
FIGS. 3-5. In one variation, the haptic 1008c has substantially
uniform arms, some of which protrude by a greater amount into the
optic 1004c. In another variation, the arms can be coupled at their
proximal ends by an inner member such as is described above.
[0149] FIG. 23D shows another embodiment of the intraocular lens
1000d in which a portion of a haptic 1008d disposed inside the
optic 1004 is asymmetric to induce asymmetry in the deformation of
the optic 1004 in response to uniform ocular forces. The
intraocular lens 1000d includes an inner member 1036d disposed
therein that is asymmetric, for example having an oval or other
elongated arcuate shape. The inner member 1036d has a first segment
along the major axis A and a second segment along the minor axis B.
The second segment is better able to bend at its midpoint than is
the first segment if the inner member 1036d is otherwise uniform.
Also, the distance from the application of force along the
mid-point of the second segment to the center of the optic is less
than the distance from the application of force at the mid point of
the first segment to the center of the optic. As a result, the
second segment is more effective at deforming the optic 1004 along
the minor axis of the inner member 1036d than is the first segment
along the major axis of the inner member 1036d such that asymmetry
in the optic can be induced. In some embodiments, the inner member
1036d may have indentations to vary the location of force applied
to the optic, or may even be separated and thus not continuous as
illustrated in FIG. 23E. Additionally, the inner member 1036d may
vary in thickness such that a first segment 1040a has a different
radial thickness than the radial thickness of a second segment
1040b as illustrated in FIG. 23F. An intraocular lens similar to
the intraocular lens 1000f illustrated in FIG. 23F having an inner
member 1036d that has a variable thickness in the radial direction
can be useful in toric lenses that can correct for astigmatism in
addition to myopia or hyperopia. In various embodiments, the inner
member 1036d can have three regions, each region having a different
thickness instead of two regions with different thickness. Such
intraocular lenses may be useful to induce or correct an asymmetric
aberration.
[0150] FIGS. 24A-24C show an embodiment 1000 where asymmetric
vaulting or tilting may occur based on the location of the
attachment of the haptic arm 1050a and 1050b to the optic 1004.
FIGS. 24A and 24B shows cross-sectional views of the intraocular
lens including the optical axis (OA) of the optic 1004. As shown in
FIGS. 24A and 24B, haptic arms 1050a along major axis A are
connected to the equatorial plane of optic 1004 (for example at the
mid-point between the anterior and posterior surfaces of the optic
1004), while the haptic arms 1050b along the minor axis B attach to
the optic 1004 in a plane away from the equatorial plane of the
optic 1004. For example, the haptic arms 1050b can attach proximal
to the anterior surface or the posterior surface of the optic 1004.
Under the influence of an ocular force, the haptic arms 1050a may
be more effective to provide compressive forces along the axis A
such that the optic 1004 is deformed (e.g. bulged or flattened).
Under the influence of an ocular force, the haptic arms 1050b may
be more effective to vault or move the optic along a direction
parallel to the optical axis OA. The combination of deformation and
vaulting may result in asymmetric accommodation.
[0151] The description of the invention and its applications as set
forth herein is illustrative and is not intended to limit the scope
of the invention. Variations and modifications of the embodiments
disclosed herein are possible, and practical alternatives to and
equivalents of the various elements of the embodiments would be
understood to those of ordinary skill in the art upon study of this
patent document. These and other variations and modifications of
the embodiments disclosed herein may be made without departing from
the scope and spirit of the invention.
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