U.S. patent application number 10/189992 was filed with the patent office on 2003-09-11 for axial-displacement accommodating intraocular lens.
Invention is credited to Phillips, Andrew F..
Application Number | 20030171809 10/189992 |
Document ID | / |
Family ID | 27807211 |
Filed Date | 2003-09-11 |
United States Patent
Application |
20030171809 |
Kind Code |
A1 |
Phillips, Andrew F. |
September 11, 2003 |
Axial-displacement accommodating intraocular lens
Abstract
An intraocular lens (IOL) system includes an optic, a pair of
haptics located on sides of the optic, and hinge portions at each
of the optic haptic junctions. The hinge portions have stressed and
non-stressed configurations. One or more restraining elements are
provided to maintain the stressed state configuration of the hinge
portion during implantation and during a post-operative period
during which the capsular bag of the eye heals about the lens. The
restraining elements are thereafter removable, preferably via a
non-surgically invasive manner, e.g., via dissolution or laser
light. Removal of the restraining elements allows anteriorization
of the optic as the lens assumes a non-stressed configuration
during accommodation. The ciliary body and lens may then interact
in a manner substantially similar to the physiological interaction
between the ciliary body and a healthy natural crystalline
lens.
Inventors: |
Phillips, Andrew F.;
(Pasadena, CA) |
Correspondence
Address: |
David P. Gordon, Esq.
65 Woods End Road
Stamford
CT
06905
US
|
Family ID: |
27807211 |
Appl. No.: |
10/189992 |
Filed: |
July 5, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10189992 |
Jul 5, 2002 |
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10090675 |
Mar 5, 2002 |
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Current U.S.
Class: |
623/6.45 ;
623/6.46; 623/907 |
Current CPC
Class: |
A61F 2/1635 20130101;
A61F 2/1629 20130101; Y10S 623/907 20130101 |
Class at
Publication: |
623/6.45 ;
623/6.46; 623/907 |
International
Class: |
A61F 002/16 |
Claims
What is claimed is:
1. An intraocular lens for replacement of a natural crystalline
lens within a capsular bag of an eye during eye surgery, said lens
comprising: a) an optic portion adapted to focus light; b) a haptic
portion about said optic portion; c) means for urging said optic
portion into an anterior configuration relative to said haptic
portion; and d) a restraining element adapted to prevent said optic
portion from moving into said anterior configuration relative to
said haptic portion, said restraining element adapted to be removed
after completion of an eye surgery, wherein upon removal of said
restraining element, said optic portion is permitted to move
anteriorly relative to said haptic portion.
2. An intraocular lens according to claim 1, wherein: said optic
has a fixed power.
3. An intraocular lens according to claim 1, wherein: said optic is
substantially rigid.
4. An intraocular lens according to claim 1, wherein: said optic is
substantially flexible.
5. An intraocular lens according to claim 1, wherein: a junction is
defined between said optic portion and said haptic portion, and
said restraining element is provided at said junction.
6. An intraocular lens according to claim 1, wherein: said
restraining element bridges said optic portion and said haptic
portion.
7. An intraocular lens according to claim 1, wherein: said
restraining element at least one of bio-resorbable, chemically
resorbable, and laser-removable.
8. An intraocular lens according to claim 1, wherein: said
restraining element is surgically removable.
9. An intraocular lens according to claim 1, wherein: a junction is
defined between said optic portion and said haptic portion, and
said means for urging is integral with said junction.
10. An intraocular lens according to claim 9, wherein: said optic
portion and said means for urging are integrally formed from a
flexible polymer.
11. An intraocular lens according to claim 1, further comprising:
e) a structure provided on said haptic portion and adapted to force
said lens posteriorly when said lens is implanted in the capsular
bag of the eye.
12. An intraocular lens for replacement of a natural crystalline
lens within a capsular bag of an eye during eye surgery, said lens
comprising: a) an optic portion adapted to focus light; b) a haptic
portion about said optic portion; c) means for urging said haptic
portion from a relatively planar configuration relative to said
optic portion into a relatively angled configuration relative to
said optic portion; and d) a restraining element adapted to
maintain said haptic portion and said optic portion in said
relatively planar configuration, said restraining element adapted
to be removed after completion of an eye surgery, wherein upon
removal of said restraining element, said haptic portion is
permitted to move into said relatively angled configuration.
13. An intraocular lens for replacement of a natural crystalline
lens within a capsular bag of an eye during eye surgery, said lens
comprising: a) an optic adapted to focus light; b) a haptic about
said optic, said optic and haptic maintained in a stressed
configuration; c) a restraining element that restrains said optic
and haptic in a stressed configuration, said restraining element
being removable from a lens implanted in the capsular bag of the
eye in a non-surgically invasive manner, wherein when said lens is
implanted in the capsular bag of the eye and said optic and haptic
are in said stressed configuration, said optic is provided in a
relatively posterior position in the eye, and when said lens is
implanted in the capsular bag of the eye, said restraining element
is removed, and said optic and haptic are biased toward said
non-stressed configuration, said optic is urged toward a relatively
anterior position in the eye.
14. An intraocular lens according to claim 13, wherein: said optic
has a fixed power.
15. An intraocular lens according to claim 13, wherein: a junction
is defined between said optic portion and said haptic portion, said
restraining element is provided at said junction.
16. An intraocular lens according to claim 13, wherein: said
restraining element bridges said optic portion and said haptic
portion.
17. An intraocular lens according to claim 13, wherein: said
restraining element at least one of bio-resorbable, chemically
resorbable, and laser-removable.
18. An intraocular lens according to claim 13, wherein: said
restraining element is surgically removable.
19. An intraocular lens according to claim 13, further comprising:
e) a structure provided on said haptic portion and adapted to force
said lens posteriorly when said lens is implanted in the capsular
bag of the eye.
20. A method of implanting an intraocular lens into an eye,
comprising: a) inducing cycloplegia; b) providing an intraocular
lens in a stressed state, said lens having an optic; c) inserting
the intraocular lens into a capsular bag of the eye; d) maintaining
cycloplegia until the capsular bag physiologically affixes to the
intraocular lens; and e) releasing the intraocular lens from the
stressed state such that said optic of said lens in a non-stressed
state moves anteriorly in the eye.
21. A method according to claim 20, wherein said releasing is
non-surgically invasive.
22. A method according to claim 20, wherein: said intraocular lens
includes a restraining means for restraining said lens in the
stressed state, and said releasing including bio-resorption,
chemical resorption, and laser-removal.
23. A method of implanting an intraocular lens into an eye,
comprising: a) inducing cycloplegia; b) providing an intraocular
lens in an unstressed state, the intraocular lens having an optic
portion and a haptic portion; c) inserting the intraocular lens
into a capsular bag of the eye; d) maintaining cycloplegia, during
which the capsular bag physiologically affixes to the intraocular
lens; and e) after the capsular bag physiologically affixes and
during cycloplegia, altering a shape of the lens such that the
optic portion is urged anteriorly relative to the haptic
portion.
24. A method according to claim 23, wherein: said lens is altered
in shape with light.
25. A method of implanting an intraocular lens into an eye,
comprising: a) providing in a non-stressed state an intraocular
lens having an optic portion and a haptic portion, wherein in said
non-stressed state said optic portion is located anteriorly
relative to said haptic portion; b) inserting the intraocular lens
in the non-stressed state into a capsular bag of the eye; c)
inducing a ciliary body of the eye into a contracted state; and d)
maintaining the ciliary body of the eye in the contracted state
until the capsular bag physiologically affixes to the intraocular
lens.
Description
[0001] This application is a continuation-in-part of U.S. Ser. No.
10/090,675, filed Mar. 5, 2002, which is incorporated by reference
herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates broadly to ophthalmic implants. More
particularly, this invention relates to intraocular lenses which
are focusable and allow for accommodation for near vision.
[0004] 2. State of the Art
[0005] Referring to FIG. 1, the human eye 10 generally comprises a
cornea 12, an iris 14, a ciliary body (muscle) 16, a capsular bag
18 having an anterior wall 20 and a posterior wall 22, and a
natural crystalline lens 24 contained with the walls of the
capsular bag. The capsular bag 18 is connected to the ciliary body
16 by means of a plurality of zonules 26 which are strands or
fibers. The ciliary body 16 surrounds the capsular bag 18 and lens
24, defining an open space, the diameter of which depends upon the
state (relaxed or contracted) of the ciliary body 16.
[0006] When the ciliary body 16 relaxes, the diameter of the
opening increases, and the zonules 26 are pulled taut and exert a
tensile force on the anterior and posterior walls 20, 22 of the
capsular bag 18, tending to flatten it. As a consequence, the lens
24 is also flattened, thereby undergoing a decrease in focusing
power. This is the condition for normal distance viewing. Thus, the
emmetropic human eye is naturally focussed on distant objects.
[0007] Through a process termed accommodation, the human eye can
increase its focusing power and bring into focus objects at near.
Accommodation is enabled by a change in shape of the lens 24. More
particularly, when the ciliary body 16 contracts, the diameter of
the opening is decreased thereby causing a compensatory relaxation
of the zonules 26. This in turn removes or decreases the tension on
the capsular bag 18, and allows the lens 24 to assume a more
rounded or spherical shape. This rounded shape increases the focal
power of the lens such that the lens focuses on objects at
near.
[0008] As such, the process of accommodation is made more efficient
by the interplay between stresses in the ciliary body and the lens.
When the ciliary body relaxes and reduces its internal stress,
there is a compensatory transfer of this stress into the body of
the lens, which is then stretched away from its globular relaxed
state into a more stressed elongated conformation for distance
viewing. The opposite happens as accommodation occurs for near
vision, where the stress is transferred from the elongated lens
into the contracted ciliary body.
[0009] In this sense, referring to FIG. 2, there is conservation of
potential energy (as measured by the stress or level of excitation)
between the ciliary body and the crystalline lens from the point of
complete ciliary body relaxation for distance vision through a
continuum of states leading to full accommodation of the lens.
[0010] As humans age, there is a general loss of ability to
accommodate, termed "presbyopia", which eventually leaves the eye
unable to focus on near objects. In addition, when cataract surgery
is performed and the natural crystalline lens is replaced by an
artificial intraocular lens, there is generally a complete loss of
the ability to accommodate. This occurs because the active muscular
process of accommodation involving the ciliary body is not
translated into a change in focusing power of the implanted
artificial intraocular lens.
[0011] There have been numerous attempts to achieve at least some
useful degree of accommodation with an implanted intraocular lens
which, for various reasons, fall short of being satisfactory. In
U.S. Pat. No. 4,666,446 to Koziol et al., there is shown an
intraocular lens having a complex shape for achieving a bi-focal
result. The lens is held in place within the eye by haptics which
are attached to the ciliary body. However, the implant requires the
patient to wear spectacles for proper functioning. Another device
shown in U.S. Pat. No. 4,944,082 to Richards et al., also utilizes
a lens having regions of different focus, or a pair of compound
lenses, which are held in place by haptics attached to the ciliary
body. In this arrangement, contraction and relaxation of the
ciliary muscle causes the haptics to move the lens or lenses,
thereby altering the effective focal length. There are numerous
other patented arrangements which utilize haptics connected to the
ciliary body, or are otherwise coupled thereto, such as are shown
in U.S. Pat. Nos. 4,932,966 to Christie et al., U.S. Pat. No.
4,888,012 to Horne et al. and U.S. Pat. No. 4,892,543 to Turley,
and rely upon the ciliary muscle to achieve the desired alteration
in lens focus.
[0012] In any arrangement that is connected to the ciliary body, by
haptic connection or otherwise, extensive erosion, scarring, and
distortion of the ciliary body usually results. Such scarring and
distortion leads to a disruption of the local architecture of the
ciliary body and thus causes failure of the small forces to be
transmitted to the intraocular lens. Thus, for a successful
long-term implant, connection and fixation to the ciliary body is
to be avoided if at all possible.
[0013] In U.S. Pat. No. 4,842,601 to Smith, there is shown an
accommodating intraocular lens that is implanted into and floats
within the capsular bag. The lens comprises front and rear flexible
walls joined at their edges, which bear against the anterior and
posterior inner surfaces of the capsular bag. Thus, when the
zonules exert a tensional pull on the circumference of the capsular
bag, the bag, and hence the intraocular lens, is flattened, thereby
changing the effective power of refraction of the lens. The
implantation procedure requires that the capsular bag be intact and
undamaged and that the lens itself be dimensioned to remain in
place within the bag without attachment thereto. Additionally, the
lens must be assembled within the capsular bag and biasing means
for imparting an initial shape to the lens must be activated within
the capsular bag. Such an implantation is technically quite
difficult and risks damaging the capsular bag, inasmuch as most of
the operations involved take place with tools which invade the bag.
In addition, the Smith arrangement relies upon pressure from the
anterior and posterior walls of the capsular bag to deform the
lens, which requires that the lens be extremely resilient and
deformable. However, the more resilient and soft the lens elements,
the more difficult assembly within the capsular bag becomes.
Furthermore, fibrosis and stiffening of the capsular remnants
following cataract surgery may make this approach problematic.
[0014] U.S. Pat. No. 6,197,059 to Cumming and U.S. Pat. No.
6,231,603 to Lang each disclose an intraocular lens design where
the configuration of a hinged lens support ostensibly allows the
intraocular lens to change axial position in response to
accommodation and thus change effective optical power. U.S. Pat.
No. 6,299,641 to Woods describes another intraocular lens that also
increases effective focusing power as a result of a change in axial
position during accommodation. In each of these intraocular lenses,
a shift in axial position and an increase in distance from the
retina results in a relative increase in focusing power. All lenses
that depend upon a shift in the axial position of the lens to
achieve some degree of accommodation are limited by the amount of
excursion possible during accommodation.
[0015] U.S. Pat. No. 5,607,472 to Thompson describes a dual-lens
design. Prior to implantation, the lens is stressed into a
non-accommodative state with a gel forced into a circumferential
expansion channel about the lens. At implantation, the surgeon must
create a substantially perfectly round capsullorrhexis, and insert
the lens therethrough. A ledge adjacent to the anterior flexible
lens is then bonded 360.degree. around (at the opening of the
capsulorrhexis) by the surgeon to the anterior capsule to secure
the lens in place. This approach has numerous drawbacks, a few of
which follow. First, several aspects of the procedure are
substantially difficult and not within the technical skill level of
many eye surgeons. For example, creation of the desired round
capsullorrhexis within the stated tolerance required is
particularly difficult. Second, the bonding "ledge" may disrupt the
optical image produced by the adjacent optic. Third, intraocular
bonding requires a high degree of skill, and may fail if the
capsullorrhexis is not 360.degree. round. Fourth, the proposed
method invites cautionary speculation as to the result should the
glue fail to hold the lens in position in entirety or over a
sectional region. Fifth, it is well known that after lens
implantation surgery the capsular bag, upon healing, shrinks. Such
shrinking can distort a lens glued to the bag in a pre-shrunk
state, especially since the lens is permanently affixed to a
structure which is not yet in equilibrium. Sixth, Thompson fails to
provide a teaching as to how or when to release the gel from the
expansion channel; i.e., remove the stress from the lens. If the
gel is not removed, the lens will not accommodate. If the gel is
removed during the procedure, the lens is only in a flattened
non-accommodating shape during adhesion to the capsule, but not
post-operatively, and it is believed that the lens therefore will
fail to interact with the ciliary body as required to provide the
desired accommodation as the capsular bag may change shape in the
post-operative period. If the gel is otherwise removed thereafter,
Thompson ostensibly requires an additional surgical procedure
therefor. In view of these problems, it is doubtful that the lens
system disclosed by Thompson can be successfully employed.
[0016] Thus, the prior art discloses numerous concepts for
accommodating intraocular lenses. However, none are capable of
providing an accommodating implant which does not, in one way or
another, risk damage to the ciliary body or the capsular bag,
present technical barriers, or present potential serious
consequences upon failure of the device.
SUMMARY OF THE INVENTION
[0017] It is therefore an object of the invention to provide an
intraocular lens that functions similarly to the natural
crystalline lens.
[0018] It is another object of the invention to provide an
intraocular lens that changes shape and increases power during
accommodation.
[0019] It is also an object of the invention to provide an
intraocular lens that produces a sufficient increase in focusing
power such that it is clinically useful.
[0020] It is an additional object of the invention to provide an
intraocular lens that permits uncomplicated implantation of the
lens in a manner compatible with modern-day cataract surgery
techniques.
[0021] In accord with these objects, which will be discussed in
detail below, an intraocular lens (IOL) system that permits
accommodation and a method of implanting such an intraocular lens
system are provided. Generally, the invention includes an
intraocular lens that is maintained in a stressed non-accommodating
configuration during implantation into the capsular bag of the eye
and maintained in the stressed configuration during a
post-operative healing period during which the capsular bag heals
about the lens. After the post-operative healing period, the
intraocular lens is preferably atraumatically released from the
stressed state and permitted to move between accommodative and
non-accommodative configurations in accord with stresses placed
thereon by the ciliary body and other physiological forces.
[0022] According to one embodiment of the invention, the
intraocular lens system includes a flexible optic having a skirt
(periphery or haptic), and a restraining element about the skirt
and adapted to temporarily maintain the flexible optic in a
stressed, non-accommodating configuration during a post-operative
period. The retraining element may comprise a dissolvable
bioabsorbable material such that the element automatically releases
the optic after a post-operative period, or may be released under
the control of a eye surgeon, preferably via a non-surgically
invasive means such as via a laser or a chemical agent added to the
eye.
[0023] According to another embodiment of the invention, the
intraocular lens system includes an optic, a pair of haptics
located on sides of the optic, and hinge portions at each of the
optic haptic junctions. The hinge portions have stressed and
non-stressed state configurations. In accord with the invention,
one or more restraining elements are provided to maintain the
stressed state configuration of the hinge portion during
implantation and during a post-operative period.
[0024] According to a preferred method of implantation, the ciliary
body muscle is pharmacologically induced into a relaxed stated
(cycloplegia), a capsulorrhexis is performed on the lens capsule,
and the natural lens is removed from the capsule. The prosthetic
lens is then placed within the lens capsule. According to a
preferred aspect of the invention, the ciliary body is maintained
in the relaxed state for the duration of the time required for the
capsule to naturally heal and shrink about the lens; i.e., possibly
for several weeks. After healing has occurred, the restraining
element automatically or under surgeon control releases the lens
from the stressed state. The ciliary body and lens may then
interact in a manner substantially similar to the physiological
interaction between the ciliary body and a healthy natural
crystalline lens.
[0025] Alternatively, a fully relaxed lens (i.e., without
restraining element) can be coupled to a fully stressed and
contracted ciliary body.
[0026] The intraocular lens system of the invention is compatible
with modern cataract surgery techniques and allows for large
increases in optical power of the implanted lens. Unlike other
proposed accommodating intraocular lens systems, the lens described
herein is capable of higher levels of accommodation and better
mimics the function of the lens of the human eye. Further, unlike
other lens systems previously described, the lens take into account
certain reciprocal aspects of the relationship between the natural
crystalline lens and the ciliary body. Moreover, the implantation
is relatively easy and rapid.
[0027] Additional objects and advantages of the invention will
become apparent to those skilled in the art upon reference to the
detailed description taken in conjunction with the provided
figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a diagrammatic view of a cross-section of a normal
eye;
[0029] FIG. 2 is a graph of the stresses on the ciliary
body-crystalline lens system of the eye in a continuum of states
between distance vision and full accommodation;
[0030] FIG. 3 is a schematic front view of an intraocular lens
according to the invention configured into a stressed state with a
restraining element;
[0031] FIG. 4 is a schematic transverse section view of the
intraocular lens of FIG. 3 in a stressed state;
[0032] FIG. 5 is a schematic transverse section view of the
intraocular lens of FIG. 3 in a non-stressed accommodating
state;
[0033] FIGS. 6 and 7 are other schematic transverse section views
of intraocular lenses according to the invention;
[0034] FIG. 8 is a schematic front view of an intraocular lens
according to the invention with the restraining element removed,
and thus, configured in a non-stressed accommodating state;
[0035] FIG. 9 is a transparent front view of an intraocular lens
according to the invention shown with a second embodiment of a
restraining element;
[0036] FIG. 10 is a schematic transverse view of the intraocular
lens of FIG. 9;
[0037] FIG. 11 is a transparent front view of an intraocular lens
according to the invention shown with a third embodiment of a
restraining element;
[0038] FIG. 12 is a schematic transverse view of the intraocular
lens of FIG. 11;
[0039] FIG. 13 is a transparent front view of an intraocular lens
according to the invention shown with a third embodiment of a
restraining element;
[0040] FIG. 14 is a schematic transverse view of the intraocular
lens of FIG. 13;
[0041] FIG. 15 is a schematic front view of an intraocular lens
according to the invention having a particular skirt configuration
which include haptics and another alternate embodiment restraining
element;
[0042] FIG. 16 is a schematic front view of another intraocular
lens according to the invention having a particular skirt
configuration which include haptics and yet another alternate
embodiment restraining element;
[0043] FIG. 17 is a schematic side view of the intraocular lens of
FIG. 16;
[0044] FIG. 18 is an intraocular lens according to the invention
having a particular skirt configuration which include haptics and
yet a further alternate embodiment restraining element;
[0045] FIG. 19 is a block diagram of a first embodiment of a method
of implanting an intraocular lens according to the invention;
[0046] FIG. 20 is a block diagram of a second embodiment of a
method of implanting an intraocular lens according to the
invention;
[0047] FIG. 21 is a block diagram of a third embodiment of a method
of implanting an intraocular lens according to the invention;
[0048] FIG. 22 is a schematic front view of a second embodiment of
an intraocular lens according to the invention, shown in a stressed
configuration;
[0049] FIG. 23 is a schematic side view of the intraocular lens of
FIG. 22, shown in a stressed configuration;
[0050] FIG. 24 is a schematic side view of the intraocular lens of
FIG. 22, shown in a non-stressed configuration;
[0051] FIG. 25 is a schematic side view of the intraocular lens
according to the second embodiment of the invention held in a
stressed configuration with a bridge-type restraining element;
[0052] FIG. 26 is a schematic side view of the intraocular lens of
FIG. 25 shown in a non-stressed configuration;
[0053] FIG. 27 is a schematic front view of an intraocular lens
according to the invention having four haptics;
[0054] FIG. 28 is a diagrammatic view of a cross-section of an eye
having an intraocular lens according to the second embodiment of
the invention implanted therein, the lens being in a stressed
configuration; and
[0055] FIG. 29 is a diagrammatic view of a cross-section of an eye
having an intraocular lens according to the second embodiment of
the invention implanted therein, the lens being in a non-stressed
configuration.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0056] Turning now to FIG. 3, a first preferred embodiment of an
intraocular lens 100 according to the invention is shown. The lens
includes a pliable optic portion 102 having an elastic memory, and
is peripherally surrounded by a skirt portion 104. A restraining
element 106 is provided on the skirt portion 104 and operates to
hold the skirt portion and optic portion 102 in a stressed (i.e.,
stretched) configuration. Comparing FIG. 3, showing the optic
portion in a stressed configuration, with FIG. 8, showing the optic
portion in a non-stressed configuration, it is seen that the optic
portion has a smaller diameter in the non-stressed
configuration.
[0057] More particularly, the optic portion 102 is typically
approximately 5 to 6 mm in diameter and made from a silicone
polymer or other suitable flexible polymer. The optic portion
defines an anterior surface 110 and a posterior surface 112. The
optic portion may have a biconvex shape in which each of the
anterior surface 110 and posterior surface 112 have similar rounded
shapes. FIG. 4 illustrates such a lens in a stressed
non-accommodating configuration, while FIG. 5 illustrates such a
lens in the non-stressed accommodating configuration.
Alternatively, referring to FIG. 6, the anterior surface 110a may
be provided with a substantially greater curvature than the
posterior surface 112a. In addition, referring to FIG. 7, the
anterior and posterior surfaces 110, 112 of the optic portion can
be evenly pliable throughout, or, referring back to FIG. 6, greater
flexibility and pliability can be fashioned into the central
portion 114 of the anterior 110 surface of the lens to enhance the
accommodating effect. This may be done by using materials of
differing modulus of elasticity or by altering the thickness of the
central portion and/or anterior surface 110 of the optic portion
102.
[0058] Referring back to FIG. 3, the skirt portion 104 has
substantially less pliability than the optic portion 102. The
periphery 116 of the skirt portion 104 is preferably provided with
a plurality of circumferentially displaced fenestration holes 118.
The fenestration holes 118 operate to promote firm attachment of
the capsular bag to the lens skirt 104 during the healing period.
That is, during the healing process, the capsular bag shrinks by a
substantial amount and portions of the anterior and posterior
capsular bag enter into the fenestration holes 118 and join
together to lock the lens 100 within the capsule without
necessitating any bonding agent, sutures, or the like.
Alternatively, the peripheral portion 104 could be fashioned with a
textured surface, ridges or any surface modification that promotes
strong adhesion of the capsule to the lens skirt 104.
[0059] Referring to FIGS. 3 and 4, according to a preferred, though
not essential, aspect of the invention, a preferably thin and
pliable collar 120 is positioned around the anterior surface of
lens near the junction 122 (FIG. 8) of the optic portion 102 and
the skirt portion 104 to keep the more central portions of the
anterior capsular remnant from adhering to the optic portion. The
collar is preferably made from silicone or another smooth
polymer.
[0060] As discussed above, the skirt portion 104 is maintained in a
stressed configuration by the restraining element until the
restraining element is removed. According to a preferred embodiment
of the restraining element, the restraining element is a band
provided on the outside of the skirt portion. The band 106 is
preferably comprised of a dissolvable, preferably bioasborbable
material that is adapted to preferably naturally dissolve in the
fluid of the eye within a predetermined period of time after
implantation. Alternatively, the dissolvable material may be
selected so that it dissolves only upon the addition of a
dissolving-promoting agent into the eye. Preferred dissolvable
materials for the restraining band 106 include collagen, natural
gut materials, glycan, polyglactin, poliglecaprone, polydioxanone,
or other carbohydrate-based or protein-based absorbable
material.
[0061] Referring now to FIGS. 9 and 10, according to a second
embodiment of the restraining element 106a, the restraining element
comprises a circumferential channel 130a in the skirt 104 that is
filled with a fluid or gel 132a. Preferably an isotonic solution
such as a balanced salt solution is used. Alternatively, other
suitable fluids, solution, or gels, including viscoelastics can be
used. The channel 130a has an outlet 134a that is blocked by a
dissolvable, preferably bioabsorbable seal 136a. The filled channel
130a operates to stress the optic portion 102 into a
non-accommodating configuration until the seal 136a is dissolved
and the outlet 134a is thereby opened. Then, the material 132a
within the channel 130a is forced out of the channel by the natural
elasticity of the lens and permits the lens to move in accord with
the excitation state of the ciliary body; i.e., between
non-accommodative and accommodative states. Alternatively, the seal
material 136a may not be naturally dissolvable within the
environment of the eye, but rather is dissolvable within the
presence of a chemical agent, such as an enzyme, which can be added
to the eye. In such case, the eye surgeon can non-surgically
control the release of the seal.
[0062] Turning now to FIGS. 11 and 12, according to a third
embodiment of the restraining element, the restraining element 106b
comprises a circumferential channel 130b in the skirt portion 104
that is filled with a balanced salt solution or other suitable
material 132b that maintains the optic portion into a
non-accommodating stressed configuration. The channel 130b has an
outlet tube 134b that is biased outward from the optic portion 108
but which is preferably anchored with an anchor 135b toward the
optic portion 102 but which preferably does not overlie a central
area of the optic portion which would interrupt the vision of the
patient when the lens is implanted. The outlet tube 134b is
provided with a seal 136b made from a material, e.g., hard
silicone, polymethylmethacrylate (PMMA) or plastic, that is
ablatable or otherwise able to be unsealed by laser light from a
YAG laser or other laser suitable for eye surgery. Likewise, the
anchor 135b is also made from such a material. When the lens is
implanted, as discussed in detail below, the anchor 135b and the
outlet tube 134b, by being directed toward the optic portion 102,
is visible to the eye surgeon through a dilated iris and is
positioned to receive laser light. In this embodiment, the seal
136b can be removed and the outlet tube 134b opened under the full
control of the eye surgeon (at his or her discretion upon
postoperative evaluation of the lens recipient) by use of a laser
to remove the pressure in the channel 130b to equilibrate with the
anterior chamber pressure of the eye. Moreover, removal of the
anchor 135b enables the outlet tube to move away from the optic
portion in accord with its bias and toward the periphery to
minimize any potential interference with the patient's vision.
[0063] According to a fourth embodiment of the restraining element,
any mechanical means for maintaining the lens in a stressed
configuration can be used. For example, referring to FIGS. 13 and
14, a relatively stiff restraining element 132c having a circular
form can be inserted or otherwise provided within a circumferential
channel 130c. The restraining element is made from a material
designed to be ablated or broken upon receiving laser energy, e.g.,
hard silicone, polymethylmethacrylate (PMMA) or plastic.
Alternatively, the end of the element 132c can be provided with a
length of flexible material 134c, e.g., suture, which can be
extended to outside the eye. When it is desired to remove the
restraining element, the surgeon grasps the suture with a forceps
and pulls the suture. This either removes the restraining element
from the lens or breaks the restraining element. In either case,
the stress is released from the optic. As yet another less
preferred alternative, stiff restraining element is removable or
broken only upon an invasive (requiring an incision) surgical
procedure.
[0064] Other embodiments for the restraining elements and removal
thereof are possible. For example, and not by way of limitation,
the seal for an inflated channel can be attached to a suture or
other length of flexible material which extends outside the eye.
The suture can be pulled by the surgeon to remove the seal. In yet
another example, shallow shells, adapted to be dissolvable
naturally or in conjunction with an additive agent, may be provided
to the front and back of the optic portion to force the optic
portion to adopt a flatter (i.e., stressed) configuration. By way
of another example, dissolvable or laser-removable arced struts may
be provided across the lens which force the optic portion into a
stressed state.
[0065] Moreover, embodiments of the restraining element which
maintain the stressed state of the optic via external flattening of
the optic or by arced struts are suitable for use with a
non-circumferential skirt portion; i.e., where the skirt portion is
defined by a plurality of haptics extending outward from the optic
portion. For example, FIGS. 15-18, illustrate the "skirt portion"
defined by a plurality of haptics, rather than a complete ring
about the optic. FIG. 15 discloses a skirt portion 104a defined by
three haptics 140a, each of which preferably includes fenestration
holes 118a. Dissolvable or laser-ablatable arced struts 142a are
situated to maintain a radial stress on the optic portion 102a;
i.e., the struts 142a function together as a restraining member.
FIGS. 16 and 17 discloses a skirt defined by four haptics 140b,
each of which preferably includes fenestration holes 118b. Shells
144b are coupled to the haptics anterior and posterior of the optic
to flatten the optic. FIG. 18 discloses a skirt defined by two
haptics 140c, each of which preferably includes fenestration holes
118c. Multiple struts 142c are coupled to each haptic 140c.
[0066] In addition, it is recognized that the optic portion may be
provided in an optically transparent bag, and the bag may be pulled
or otherwise forced taught to stress the optic. The bag may be
pulled taught by using one of the restraining element described
above, e.g., retaining rings, channels, shells, or struts, or any
other suitable means, provided either directly to the bag or
provided to an element coupled about a periphery of the bag.
[0067] Moreover, it is recognized that the lens of the invention
may comprise two optic elements: one stationary and the other
adapted to change shape and thereby alter the optic power of the
dual optic system. In such an embodiment, the optic element adapted
to change shape would be provided in a stressed-configuration,
according to any embodiment described above.
[0068] In each embodiment of the restraining element, the
restraining element is preferably configured on or in the lens
during manufacture, such that the lens is manufactured, shipped,
and ready for implant in a fully stressed configuration.
[0069] The lens is implanted according to a first method of
implantation, as follows. Referring to FIG. 19, the patient is
prepared for cataract surgery in the usual way, including full
cycloplegia (paralysis of the ciliary body) at 200. Cycloplegia is
preferably pharmacologically induced, e.g., through the use of
short-acting anticholinergics such as tropicamide or longer-lasting
anticholinergics such as atropine.
[0070] An anterior capsullorrhexis is then performed at 202 and the
lens material removed. A stressed lens according to the invention
is selected that preferably has an optic portion that in a
stressed-state has a lens power selected to leave the patient
approximately emmetropic after surgery. The lens is inserted into
the empty capsular bag at 204.
[0071] Cycloplegia is maintained for several weeks (preferably two
to four weeks) or long enough to allow the capsular bag to heal and
"shrink-wrap" around the stressed and elongated lens at 206. This
can be accomplished post-operatively through the use of one percent
atropine drops twice daily. As the lens shrinks, the anterior and
posterior capsular bag walls enter into the fenestration holes and
join together to lock the lens in position.
[0072] If the lens includes a restraining element having a
dissolvable component, eventually the dissolvable material is lost
from the lens, and the lens is unrestrained. If the lens includes a
restraining element having a laser-removable component, a surgeon
may at a desired time remove the component to place the lens in a
unrestrained configuration. If the lens includes a retraining
element which must be surgical removed or altered, the surgeon may
at a desired time perform a second eye procedure to remove the
component and place the lens in an unrestrained configuration.
[0073] Regardless of the method used, when the lens is unrestrained
(i.e., released from the stressed state) at 208 and the
postoperative cycloplegic medicines are stopped at 210 the lens is
initially still maintained in a stressed state (FIG. 4) due to the
inherent zonular stress of the non-accommodating eye. When the
patient begins accommodating, the zonular stress is reduced and the
implanted lens is permitted to reach a more relaxed globular
conformation, as shown in FIGS. 5 and 8. This change in shape
provides the optic with more focusing power and thus accommodation
for the patient is enabled. As with the natural crystalline lens,
the relaxation of the implanted lens to a more globular shape is
coupled with a development of strain or stress in the ciliary body
during accommodation. Further, when the patient relaxes
accommodation, the stress in the ciliary body is reduced, and there
is a compensatory gain in stress as the lens is stretched into its
non-accommodative shape (See again FIG. 2).
[0074] Referring to FIG. 20, according to another embodiment of the
method of the invention, a lens of similar design as described
above is used, except that there is no restraining element on the
lens. Temporary cycloplegia is induced, and a capsulorrhexis is
performed 300. The lens is implanted while the ciliary body is in a
fully relaxed state at 302. The patient is then fully accommodated
(i.e., the ciliary body is placed in a contracted state) at 304,
preferably through pharmacological agents such as pilocarpine.
[0075] Once the capsular bag is fully annealed (affixed) to the
lens periphery at 306, the pharmacological agent promoting
accommodation is stopped at 308. Then, as the ciliary body relaxes,
the lens is stretched into an elongated shape having less focusing
power. Conversely, as accommodation recurs, the lens returns to it
resting shape having greater focusing power.
[0076] Referring to FIG. 21, in yet another embodiment of the
method of the invention, the patient is cyclopleged during cataract
surgery at 400, a capsulorrhexis is performed at 402, and a
flexible lens in an unstressed state is implanted in the capsular
bag at 404. After a few weeks of complete cycloplegia and during
which capsular fixation of the lens periphery is accomplished at
406, light (e.g., ultraviolet or infrared), a chemical agent, or
another suitable means is used to shrink or otherwise alter the
optic or the adjacent skirt of the lens while the patient is still
fully cyclopleged at 408. In this manner, the optic is again placed
into a stressed configuration while the ciliary body is fully
relaxed. As with previous embodiments, when cycloplegia is stopped
and accommodation occurs at 410, the lens is able to return to a
more relaxed globular configuration.
[0077] The intraocular lens systems described with respect to FIGS.
1 through 18 operate to provide accommodation through a change in
shape in the optic resulting from an equilibrium of the anatomical
forces and the forces in the lens. As now described, it is also
possible to provide accommodation through axial movement of a lens
within the eye, all while maintaining equilibrium between the
anatomical forces and the structural stress designed into the
lens.
[0078] Turning now to FIGS. 22 through 24, an embodiment of another
intraocular lens system according to the invention is shown. The
lens 500 includes a central optic 502, two peripheral haptics 504,
and a junction 506 between the optic 502 and the haptics 504. The
junction 506 preferably has an elastic memory such that, in a
relaxed configuration of the lens 500, free ends 505 of the haptics
504 are oriented at a posterior angle .alpha. relative to the optic
502 (FIG. 24). A preferred range for angle .alpha. includes 1 to 60
degrees, with a more preferred angle .alpha. being 25 to 35
degrees. The junction 506 can be a skirt portion attached about the
periphery of the optic, or can be integrated into the periphery of
the optic, particularly where the optic and junction are unitarily
formed as one piece from a flexible polymeric material. In
addition, the junction 506 can vary in size allowing elastic bias
over part or all of the haptic. For instance, the unstressed
conformation of the haptic can describe an arc over all or part of
its length. A restraining element 508 is preferably provided either
at the junction 506 to restrain flexing at the junction (FIGS. 22)
or extends as a bridge from the optic 502 to the haptics 504 (FIG.
25) to maintain the lens 500 in a stressed preferably substantially
planar configuration during implantation and for a post-operative
period. Alternatively, the stressed configuration can be any
configuration of the lens in which the optic is oriented in a more
posterior orientation relative to the haptic than in the
non-stressed configuration. When the restraining element 508 is
removed, the haptics 504 are biased toward an angled configuration
relative to the optic 502, with the optic moved anteriorly relative
to the haptics (FIG. 26).
[0079] More particularly, the optic 502 can be a flexible
construction, as in the previous embodiments, or may be
substantially rigid. The optic is preferably fixed in power, but
may contain zones of different optic power. As such, the optic is
either constructed of a suitable flexible polymer such as a
silicone polymer, or a suitable stiff plastic such as
polymethylmethacrylate (PMMA). The optic preferably has a diameter
of approximately 4 mm to 7 mm, and most preferably approximately 5
mm.
[0080] The haptics 504 can be substantially planar, curved or
loop-like in structure; i.e., they may generally conform to any
well-known haptic structure. Moreover, as shown in FIG. 27, there
may be more than two haptics, e.g., four haptics 504a. Furthermore,
as described with respect to the previous embodiments, the haptics
504 may be provided with any number of surface modifications,
including knobs, protuberances, textures, fenestration holes,
ridge, etc., that promote strong adhesion with the shrink-wrapped
capsular remnant. For example, referring back to FIGS. 25 and 26, a
peripheral ridge 510 may be provided to the haptics 504. The ridge
510 promotes adhesion as well as forces the lens into a more
posterior portion of the capsular bag upon implantation, which may
be desirable. In addition, the haptics may contain portions of
varying flexibility, such as a more flexible peripheral extent to
promote flexion of the peripheral haptic against the capsular
rim.
[0081] The restraining elements 508, as described with respect to
the earlier embodiments, are preferably bio-resorbable, chemically
resorbable, laser-removable, or surgically removable. Any
restraining element that is removable in the one of the above
listed manners or in any other relatively atraumatic manner and
which provides the necessary function of maintaining the lens in a
relatively planar stressed configuration during implantation and
during a post-operative period can be similarly used.
[0082] The lens 500 is implanted as described above. That is,
cycloplegia is induced, an anterior capsullorrhexis is performed
and the lens material removed. Referring to FIG. 28, the lens, in a
stressed, substantially planar configuration is inserted into the
empty capsular bag. Cycloplegia is maintained long enough to allow
the capsular bag to heal, "shrink-wrap", and fibrose around the
stressed lens. After the bag has healed, cycloplegia is terminated
and the restraining element (not shown in FIG. 28) is removed.
[0083] Referring to FIG. 29, with the lens unrestrained, the optic
502 of the lens 500 is able to move anteriorly forward during
accommodation and increase the focusing power of the eye. The optic
502 moves forward for at least two reasons. First, with
accommodation, the stress in the ciliary body 16 is increased
causing constriction of the ciliary body, and resultant reduced
tension on the zonules 26. This allows bending of the haptic-optic
junction 506 back to its relaxed non-planar configuration. Second,
during accommodation there is anterior movement of the ciliary body
16.
[0084] Then, when the patient relaxes accommodation, the stress in
the ciliary body 16 is reduced and the ciliary body dilates and
moves posteriorly. There is a compensatory gain in stress across
the optic-haptic junction 506 as the junction is bent against its
memory into a more planar configuration and the optic 502 moves
posteriorly (See again FIG. 28).
[0085] In addition, as discussed above with respect to the first
embodiment, a photoreactive intraocular lens may be implanted in an
unstressed state. After capsular fixation of the lens, light (e.g.,
ultraviolet or infrared), a chemical agent, or another suitable
means is used to alter the optic into a stressed configuration
while the ciliary body is fully relaxed. Then, when cycloplegia is
stopped and accommodation occurs, the lens is able to return to
non-stressed configuration in which the lens is located anteriorly
relative to the haptic portion.
[0086] Moreover, as also discussed above with respect to the first
embodiment, the lens can be implanted in the eye in a non-stressed
configuration, and the ciliary can be pharmacologically induced to
contract during the healing period. After healing, pharmacological
inducement of ciliary contraction is stopped, and the lens operates
in the same manner as described above.
[0087] There have been described and illustrated herein several
embodiments of an intraocular lens and methods of implanting the
same into an eye. While particular embodiments of the invention
have been described, it is not intended that the invention be
limited thereto, as it is intended that the invention be as broad
in scope as the art will allow and that the specification be read
likewise. Thus, while two particular states of intraocular lenses
(fully stressed and fully accommodating) have been disclosed, it
will be appreciated that there is a continuum of states of stress
that can be fashioned in the inserted lens that would be
appropriate for any given state of the ciliary body. In addition,
while particular types of materials have been disclosed for the
lens, the dissolving material, and a viscoelastic material (where
used), it will be understood that other suitable materials can be
used. Also, while exemplar pharmacological agents are disclosed for
maintaining a state of the ciliary body, it is understood that
other agents can be used. Furthermore, while the skirt has been
shown comprised of two to four haptics, it is recognized that a
single haptic or five or more haptics may be utilized. Moreover,
while the restraining struts and shells have been described with
respect to skirts comprising haptics, it will be appreciated that
the restraining struts and shells can be used with a circular
skirt, as described with respect to the preferred embodiments. In
addition, while in the second embodiment the optic-haptic junction
is stated to preferably have a memory, it is appreciated that other
means may be employed to cause the haptics to assume a non-stressed
angle configuration relative to optic. For example, an elastic
membrane or struts may connect the free ends of the haptics to urge
the free ends toward each other and consequently the optic forward.
It will therefore be appreciated by those skilled in the art that
yet other modifications could be made to the provided invention
without deviating from its spirit and scope as claimed.
* * * * *