Intraocular lens with ridges

An intraocular lens for implantation in the posterior chamber of the eye including an optic having a posterior surface and first and second ridges adjacent the periphery of the optic and projecting generally posteriorly from the posterior surface. The ridges are circumferentially spaced to define openings between the ridges. Fixation members are mounted on the optic for at least assisting in retaining the optic in the posterior chamber with the ridges in contact with the posterior capsule of the capsular bag to space the posterior surface of the optic from the posterior capsule. The fixation members have knees adjacent the periphery of the optic which facilitate insertion of the intraocular lens into the eye.

BACKGROUND OF THE INVENTION 
In cataract surgery, the natural lens is removed. To refocus the light on 
the retina and thus restore vision, an intraocular lens is implanted in 
place of the natural lens. 
The intraocular lens can be implanted at various locations within the eye, 
such as within the capsular bag in the posterior chamber. After 
implantation of the intraocular lens in the capsular bag, it is sometimes 
necessary to perform a surgical technique known as discission in which an 
opening is formed in the posterior capsule. Discission has been performed 
with mechanical cutting instruments, such as a needle, and more recently, 
with a surgical laser. Discission may be necessary, for example, to 
restore vision that has become clouded following implantation of the 
intraocular lens. 
A typical intraocular lens includes an optic and fixation members, with the 
optic having a flat posterior surface which seats against the posterior 
capsule. To avoid pitting of the posterior surface of the optic when 
discission is carried out with a surgical laser, it is necessary to space 
the posterior surface from the posterior capsule. 
One way of spacing the posterior surface of the optic from the posterior 
capsule is to form an annulus on the posterior surface of the optic, and 
examples of such construction are shown in Shearing U.S. Pat. No. 
4,159,546 and Hoffer U.S. Pat. No. 4,244,060. Alternatively, the posterior 
surface of the optic can be made concave so that the posterior periphery 
of the optic engages the posterior capsule with central regions of the 
posterior surface being spaced from the posterior capsule. Unfortunately, 
these annular posterior projections on the optic tend to hamper insertion 
of the intraocular lens into the eye. More specifically, the annular 
projection is difficult to slide across the iris and causes portions of 
the iris, in effect, to build up in front of the advancing projection. 
The annular projections have other disadvantages. For example, they add 
weight to the intraocular lens and tend to inhibit the escape of tissue 
debris or cortical remnants. If the optic becomes decentered, the annular 
projection may cause visual aberrations. The annular projection may also 
enable wrinkles to form in the posterior capsule. Wrinkles are undesirable 
when discission is being carried out. Finally, gripping of the optic with 
forceps necessarily involves gripping of the annular projection, and this 
can cause structural failure of the projection. 
SUMMARY OF THE INVENTION 
This invention provides an intraocular lens which spaces the posterior 
surface of the optic from the posterior capsule and which overcomes or 
reduces the disadvantages noted above. This is accomplished by eliminating 
the annular projection of the prior art in favor of first and second 
circumferentially spaced ridges which project generally posteriorly from 
the posterior surface of the optic. These ridges stably support the optic, 
space the posterior surface of the optic from the posterior capsule and 
can serve as runners to facilitate insertion of the intraocular lens into 
the eye. The ridges are spaced circumferentially and define openings so 
the ridges tend to glide across the iris like runners rather than tending 
to cause portions of the iris to build up and impede insertion of the 
intraocular lens. 
Because the ridges do not form an annulus, less material is required for 
the optic, and consequently, the weight of the optic is reduced as 
compared with an optic of equal diameter having the annular projections. 
Alternatively, the optic of this invention can have about the same weight 
as such a prior art optic and be of larger diameter. 
The ridges are also useful in removing wrinkles which may tend to form in 
the posterior capsule. In this regard, the ridges engage the posterior 
capsule so that, when the optic is biased posteriorly by the fixation 
members, the ridges bear against the posterior capsule and tend to stretch 
the posterior capsule so as to eliminate or minimize wrinkles. Because the 
ridges are spaced circumferentially, there is no material between them to 
inhibit stretching of the posterior capsule. In addition, this 
circumferential spacing provides a space to permit the escape of cortical 
remnants, and this space is less likely to cause visual aberrations in 
case of decentering than would an annular projection. 
The ridges are adjacent the periphery of the optic, and to facilitate 
manufacture, are preferably flush with portions of the periphery of the 
optic, respectively, where the ridges meet such portions of the periphery. 
Although the ridges could be discontinuous, they are preferably continuous 
and have opposite ends which are spaced apart to define openings between 
the ridges. The ridges and the posterior surface preferably cooperate to 
define a channel-like construction with the openings being on the opposite 
ends of the channel-like construction. When so constructed, the ridges are 
more likely to act like runners to facilitate insertion of the lens into 
the eye. 
The ridges must be sufficiently long so that the axis of the optic will not 
tilt unacceptably relative to the optical axis of the eye when in use. On 
the other hand, the ridges should not be so long that they cannot act as 
runners to facilitate insertion of the intraocular lens into the eye. 
Although the circumferential length of the ridges can vary, a 
circumferential extent of about 71 degrees to about 79 degrees is 
preferred, and the middle of that range is considered optimum. Also, the 
ridges are preferably generally opposite of each other. 
Another function which the ridges can serve is to mount, or assist in 
mounting, the fixation members. For this purpose, each of the ridges may 
have a radially thickened section for receiving an inner end portion of 
the associated fixation member. 
Each of the fixation members can advantageously be in the form of a 
resilient, flexible strand. Another feature of this invention is the 
configuring of the strands to facilitate insertion of the intraocular lens 
behind the iris. This is accomplished by providing a knee at an 
appropriate location along each of the strands which deflects into a 
sharper bend or corner when the strand is deflected radially inwardly. 
This corner can then be positioned behind the iris with relative ease. 
The invention, together with additional features and advantages thereof, 
may best be understood by reference to the following description taken in 
connection with the accompanying illustrative drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1 and 2 show an intraocular lens 11 which is designed for use with 
extracapsular cataract extraction and which includes an optic 13 and 
fixation members in the form of strands 15 and 17. The optic 13 has a 
circular periphery 19, a planar, posterior surface 21 and identical ridges 
23 and 25 projecting generally posteriorly from the posterior surface. The 
intraocular lens 11 is adapted to replace the natural lens of the human 
eye and the optic 13 may be, for example, a plano-convex lens of suitable 
diopter power. As such, the optic 13 has a convex anterior surface 27 
(FIG. 2). The optic 13 may be constructed of a suitable, biocompatible 
material, such as polymethylmethacrylate. The optic 13 also has 
positioning apertures 29 adjacent the periphery 19. The optic 13 may be of 
relatively large diameter and may, for example, have a diameter of 6.5 
millimeters. 
The ridges 23 and 25 are spaced circumferentially and diametrically 
opposed. The ridges 23 and 25 need not be diametrically opposite but, 
preferably, central regions of the ridges are not offset by more than 35 
and 38 degrees from being diametrically opposite. In the embodiment 
illustrated, each of the ridges 23 and 25 is continuous and extends 
circumferentially for about 75 degrees. 
Each of the ridges 23 and 25 has an outer peripheral surface 31 which is 
generally cylindrical, of the same diameter as the optic 13 and flush with 
a portion of the periphery 19 of the optic. Each of the ridges 23 and 25 
has a planar posterior surface 32, a curved inner surface 34 and opposite 
ends 33 and 35. As shown in FIG. 1, the ends 33 and 35 of the ridges 23 
and 25 are spaced apart circumferentially to define circumferential 
openings 37 and 39. As such, the ridges 23 and 25 cooperate with the 
posterior surface 21 to define a channel-like construction, with the 
openings 37 and 39 being on the opposite ends of the channel-like 
construction. The openings 37 and 39 are sufficiently wide so that the 
ridges 23 and 25 can act as runners to facilitate insertion of the 
intraocular lens 11 into the eye. 
The strands 15 and 17 are mounted on the optic 13 at the ridges 23 and 25, 
respectively, and for this purpose, each of the ridges has a radially 
thickened section 41. The radially thickened sections 41 are diametrically 
opposed and are located closer to the ends 35 than the ends 33 of the 
associated ridge 23 and 25. The sections 41 provide the necessary strength 
and dimensions for mounting of the strands 15 and 17. 
Although the strands 15 and 17 can be mounted on the optic 13 in different 
ways, in the embodiment illustrated, a bore 43 is drilled into the 
periphery 19 at the ridges 23 and 25, and an axially extending cross bore 
45 is drilled into each of the ridges 23 and 25 from the posterior surface 
32. The bores 43 need not lie entirely within the associated ridges 23 and 
25, and in the embodiment illustrated, each of the bores 43 opens 
partially anteriorly of the associated ridge as shown in FIG. 2. The bores 
43 receive the inner end portions of the strands 15 and 17, and a hot rod 
(not shown) can be inserted into the cross bores 45 to melt the ends of 
the strands to form a head 47 which locks the strands to the associated 
ridge. 
The strands 15 and 17 are identical, and although each of them may comprise 
one or more filaments, in this embodiment each of them is integrally 
constructed of a flexible, resilient material, such as polypropylene. Each 
of the strands 15 and 17 includes an inner section 49, an intermediate 
section 51 joined to the inner section at a knee 53 to form an obtuse 
angle "A" and an outer section 55 terminating in an outer end 57 joined to 
the distal end of the intermediate section. The inner sections 49 and the 
intermediate section 51 are linear, and in the unstressed condition, the 
sections 49 are parallel and the sections 51 are parallel. The outer 
sections 55 are approximately half circular. A location 59 on each of the 
outer sections 55 is at a maximum distance from the center of the optic 13 
in the unstressed condition of the strands 15 and 17, and each of the 
locations 59 lies on a circle 60 having its center at the center of the 
optic. 
In the illustrated embodiment, the strands 15 and 17 project anteriorly at 
a 10-degree angle as shown in FIG. 2. Thus, the strands 15 and 17 project 
generally radially of the optic 13. 
The obtuse angle "A" may be of various sizes and, in the embodiment 
illustrated, is approximately 150 degrees. The angle "A" causes the 
intermediate section 51 to extend somewhat circumferentially of the optic 
13 in a first circumferential direction partially across the associated 
opening, and the part-circular nature of the outer section 55 extends in 
such a direction as to cause the strand to extend circumferentially in 
that direction partially across the associated opening and ultimately loop 
back toward the optic. Thus, the inclination of the intermediate sections 
51 and the curvature of the outer section 55 is such as to bring the 
strands 15 and 17 partially across the openings 37 and 39, respectively. 
The strands 15 and 17 are resiliently deformable at the associated knees 53 
such that the strands can be deflected inwardly to the dashed-line 
positions shown in FIG. 1. This materially reduces the obtuse angle to 
form the knee 53 into a much sharper bend. This is for the purpose of 
enabling the knee 53 to more easily get behind the iris during the lens 
insertion procedure. 
The knee 53 is at a location along the associated strand which is no more 
than about one-third the distance along the strand from the optic to the 
periphery 19 to the location 59. Preferably, the knee 53 lies along a 
tangent 61 tangent to a peripheral location 63 which, in turn, is defined 
by the intersection of a diametral line 65 and the periphery 19. The 
diametral line 65 bisects the optic 13 between the inner sections 49, and 
in this embodiment, is parallel to the inner sections. The knee 53 can be 
at various locations along the tangent 61, and this is controlled by the 
angle at which the inner section 49 projects from the optic 13. In this 
embodiment, the inner ends of the strands 15 and 17 are diametrically 
opposed along a diametral line 67, and the inner sections 49 form an 
obtuse angle "B" with the diametral line 67. Although the angle "B" may 
vary widely, in this embodiment, it is approximately 110 degrees. 
The intraocular lens 11 is adapted to be implanted in the posterior chamber 
69 following extracapsular extraction of the natural lens. FIGS. 3 and 4 
show the intraocular lens implanted in the posterior chamber 69 with the 
optic 13 contacting the capsular bag 71 behind the iris 73. Although the 
intraocular lens 11 can be mounted within the capsular bag 71, as shown in 
FIG. 4, the strands 15 and 17 engage the ciliary sulcus 75 to retain the 
optic 13 in the posterior chamber 69. When so mounted, the strands 15 and 
17 are resiliently deformed radially inwardly to retain the optic 13 
essentially coaxial with the iris 73. The strands 15 and 17 resiliently 
urge the optic 13 posteriorly and urge the ridges 23 and 25 into contact 
with the posterior capsule 77 to space the posterior surface 21 anteriorly 
of the posterior capsule. This can also be seen in FIG. 2 where the 
posterior capsule 77 is represented by a broken line. Accordingly, 
discission can be carried out with a surgical laser without pitting the 
optic 13. In addition, the urging of the ridges 23 and 25 against the 
posterior capsule 77 tends to stretch the posterior capsule to remove 
wrinkles and to resist formation of new wrinkles. This wrinkle-inhibiting 
feature is particularly effective against wrinkles which extend generally 
transverse to a line between central regions of the ridges 23 and 25. 
The intraocular lens 11 can be implanted in accordance with known 
techniques. However, the ridges 23 and 25 can be used as runners so the 
intraocular lens can glide through the incision formed in the eye for 
implantation purposes and across the iris 73. Thus, the direction of 
insertion should be generally parallel to the ridges 23 and 25. When 
gripping the lens 11 with forceps, the forceps can grip the optic 13 
between the ridges 23 and 25 so there is no danger of the forceps causing 
structural failure of the ridges. 
During the implantation procedure, the intraocular lens is slid along the 
iris 73, and when the knee 53 of the trailing strand is near the aperture 
79 of the iris 73, the trailing strand is deflected radially inwardly by 
the surgeon generally to the dashed-line position of FIG. 1 to form the 
knee 53 into a sharper bend which facilitates placement of such knee 
through the opening 79 and behind the iris 73. 
Although an exemplary embodiment of the invention has been shown and 
described, many changes, modifications and substitutions may be made by 
one having ordinary skill in the art without necessarily departing from 
the spirit and scope of this invention.