GB2167306A

GB2167306A - Intraocular implant

Info

Publication number: GB2167306A
Application number: GB08509855A
Authority: GB
Inventors: Albert R Richard
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-11-15
Filing date: 1985-04-17
Publication date: 1986-05-29
Also published as: NO850990L; BR8502042A; ES8607002A1; CA1259452A; IT1186713B; GB2167306B; IN162737B; FR2572927A1; ES542141A0; IT8520940A0; NO158988B; SE8501856L; GB8509855D0; KR860003820A; NO158988C; AU4207085A; AU557565B2; CN85103328B; CN85103328A; DE3528258A1

Abstract

An intraocular implant of the type having a lens (12) and one or more flexible lens retaining legs (16) extending therefrom for seating in an eye chamber, in which the free end of at least one of the legs (16) has means for latching engagement with a co-operating latching portion (30) on the periphery (14) of the lens, which is so positioned circumferentially on the peripheral portion that when the end of the leg is latched therein, the leg is flexed around the edge of the peripheral portion so that the lateral dimension of the implant is substantially no greater than that of the lens and peripheral portion alone thereby facilitating insertion of the implant through an incision into the eye. Preferably the peripheral portion of the lens body has an upwardly projecting leg support member against which the leg bears when it is flexed around the lens body, which controls the amount of bending of the leg and distributes the bending throughout a substantial portion of the length of the leg. <IMAGE>

Description

SPECIFICATION Intraocular implant The invention relates to implants comprising a lens body.

The insertion of such an implant requires that an incision be made in the eye for the removal of the natural lens and insertion of the implant, which is formed of biological inert and transparent material such as polymethyl methacrylate. The length of the incision needed depends on the overall width of the implant to be inserted. Any reduction in the width of the implant would allow a reduction in the length of the incision, which is desirable since the smaller the incision, the less difficult is the post-operative recovery and the shorter the healing period.

Although at least three retaining legs are considered desirable for such implants to ensure reliable retention and centering, many such implants employ only two flexible retaining legs, since implants with two legs can be made to pass through a narrower incision than an implant with three or more legs. Even if they have only two legs, insertion of the implant into the eye is difficult, since the first leg passed into the incision must be flexed against eye tissue to allow the lens to be inserted far enough to allow the second leg to enter the incision and seat in the proper cavity in the eye.

The invention accordingly provides an intraocular implant comprising a lens body and at least one flexible retaining leg extending from the lens body to a distal portion, the distal portion and the lens body having cooperating means to enable the distal portion to be releasably attached to the lens body.

The intraocular implant of the invention is formed of a plastics material suitable for the purpose, for example polymethyl methacrylate.

The lens body can comprise a central lens portion and a peripheral lens support portion disposed around the lens portion, with the at least one flexible retaining leg extending from the peripheral lens support portion. In the unrestrained condition the flexible retaining leg extends around at least a portion of the peripheral portion in radial spaced relation thereto, and terminates in a free end. The free end is provided with latching means, and the peripheral portion of the lens body is provided with co-operating latch means to receive the free end of the leg in releasable latching engagement.The co-operating latch means on the lens body is so circumferentially positioned and the leg is so dimensioned that when the leg is flexed inwardly to enable the free end to be engaged with the latch, the leg lies along the outer edge of the peripheral portion, so that the overall width of the implant, when ready for insertion into the eye, is no greater than the width of the lens body alone.

Preferably, the peripheral portion of the lens body is provided with upstanding lateral support means for the leg so positioned that when the leg is flexed around the body for attachment of the free end to the body, the leg bears against the lateral support means which thereby controls the amount of inward flexing of the leg to distribute the flexing along a substantial portion of the leg and prevents excessive flexing at the root of the leg.

An implant with any desired number of the retaining legs can be provided, with means for attaching each leg to the lens body, so that the overall width of the implant is not increased by the presence of the legs.

The invention is further explained below, by way of illustration, with reference to the accompanying drawings, in which: Figure 1 is a plan view of an intraocular lens implant embodying the invention in the condition as manufactured, with flexible retaining legs which are unrestrained; Figure 2 is a side view of the implant of Figure 1; Figure 3 is a perspective view of the implant of Figure 1; Figure 4 is a top plan view of the implant of Figure 1 with the flexible retaining legs latched onto the lens body in condition for insertion into the eye; Figure 5 is a side view of the implant in the condition of Figure 4; Figure 6 is a view of the implant after it has been inserted into the eye and the legs released; Figure 7 is a plan view of a second implant embodying the invention, again with flexible retaining legs in an unrestrained condition; and Figure 8 is a view of the implant of Figure 7 in which the flexible legs have been latched onto the lens body in preparation for insertion into the eye.

Figures 1-5 of the drawing illustrate a first embodiment of the invention, in the form of an implant 10 comprising a lens body having a central lens portion 12, a peripheral support portion 14, and a pair of resilient retaining legs 16.

The central lens portion 12 may be of any desired shape in transverse section to provide the desired lens effect. The peripheral portion 14 extends around the entire periphery of the lens portion 12 and an upwardly extending rib 18 extends around the peripheral portion.

Each retaining leg 16 is an integral part of the peripheral portion 14 and extends therefrom around the lens body in radial spaced relation thereto terminating in a free end 20 which has a laterally enlarged portion 22 having an aperture 24 therethrough. The legs 16 have a proximal portion 26 which tapers from the root, that is, the junction with the peripheral portion 14, to a position shown in Figure 1 as point "A", and a distal portion 28 of substantially uniform width from point "A" to the enlarged portion 22. This configuration of the retaining leg provides a portion of uniform thickness for seating in an eye chamber, yet allows the stress of bending to be distributed along the leg to reduce the possibility of fracture of the leg at the root.

The radius of curvature of the leg 16 gradually increases from the root to the enlarged portion 22. A portion 29 immediately adjacent the enlarged portion 22 is turned inwardly for a purpose to be described.

The rib 18 is provided with a pair of slots 30 extending therethrough in a generally radial direction, with each slot being suitably positioned to receive the free end 20 of a leg 16 in a manner such that the enlarged portion 22 is disposed inwardly of the rib and the adjacent portion of the leg being disposed in the slot, as shown in Figure 4.

Preferably, when the free ends 20 are so engaged in the slots 30, the rest of the leg is curved around the outer edge of the peripheral portion 14 inside a circle concentric with the outer edge, as illustrated in Figure 4, which shows in solid line the implant in condition for insertion into the eye.

As illustrated in Figure 4, the implant 10, when the legs 16 are latched onto the peripheral portion 14, has a width or transverse dimension that is no greater than that of the peripheral portion alone, so that the use of the implant requires a minimum length of surgical incision.

The implant 10 is supplied to the surgeon in the condition shown in Figure 1, with the legs 16 un-restrained and un-stressed. In preparation for insertion, the legs 16 will be flexed inwardly and the leg portions 29 adjacent the enlarged portions 22 placed into the slots 30.

The tendency of the flexed legs to resile will pull the enlarged portions 22 snugly against the ribs 18 on opposite sides of the slots 30, so that the legs are retained in the flexed condition. After the implant 10 has been inserted through the incision into the eye, the enlarged ends 22 are lifted out of the slots 30 by a suitable tool so that the legs 16 can resile outwardly into the surrounding eye chamber.

It will be understood that some surgeons may prefer to attach the end of only one of the legs 16 to the lens prior to insertion.

In the implant 10 of Figures 1-6 the rib 18 is divided into two portions by the slots 30, each portion having an outer surface which progresses radially inwardly as it approaches the slot, and is so positioned that as the leg 16 is flexed inwardly for engagement with the rib, it bears against this outer surface, thereby reducing the amount of bending force applied to the root of the leg at the point of attachment to the lens body. The engagement of the leg with this outer surface also controls the amount of bending of the distal portion of the leg, and provides support thereto to prevent damage to the leg during handling prior to and during insertion into the eye.

In many types of implant, the retaining legs are slightly inclined rearwardly in relation to the plane of the lens so as to maintain the lens in a desired position in relation to certain portions of the eye structure. If the legs 16 are so inclined, they must be flexed slightly forwardly to allow the legs to be curved around the rib 18 and latched into the slots 30. The legs 16 will therefore be supported against downward flexing by the support portion 14 lying just outside the rib, so that any tendency to become disengaged from the slot will be prevented.

Figures 7 and 8 illustrate a second implant 40 embodying the invention. The implant 40 comprises a lens body having a central lens portion 42 and a peripheral portion 44, with three resilient retaining legs 48 extending from the peripheral portion around the lens body in spaced relation thereto. The peripheral portion 44 has three rib segments each with a transverse slot 50 formed therein, which is circumferentially positioned to receive the free end of a leg, so that an enlarged portion 52 on the free end is retained on the inner side of the rib segment, as previously described in connection with the embodiment of Figures 16.

When the three legs 48 are flexed inwardly to curve around the outer edge of the peripheral portion 44 and the ends of the legs are placed in the slots 50 so that the enlarged portions 52 are retained on the inner side of the rib segments, the overall width of the implant 40 is no greater than that of the lens body alone, so that the provision of three retaining legs on the lens body does not require a surgical incision any longer than if only two legs were provided.

In each of the illustrated implants 10 and 40, the ribs are on the front of the implant, so that the legs 16 and 48 are attached on the front of the implant. This not only facilitates release of the legs from the slots after the implant has been inserted into the eye, but also ensures that the implant will not be inserted into the eye backwards, that is, with the rear lens surface facing outwardly, as has been known to occur.

Although in both the illustrated implants, means is provided for attaching each leg to the lens body, it will be understood that in some cases, provision may be made for attaching only one leg. For example, in using the implant 10, the surgeon may find it necessary to attach only one leg to the body before inserting the implant. Consequently, the implant 10 for certain applications be modified to have provision for attaching only one leg 16 to the body. Similarly, the implant 40 of Figures 7 and 8, may be modified to have provision for attaching only one or two of the legs 48 to the body.

The means for attaching the leg to the body has been illustrated as an enlarged end on the leg, and a slot in the peripheral rib to receive the end of the leg. It will be understood that other means for attaching the or each leg to the body may be provided.

Also, although the illustrated implants are formed integrally, of a single piece of material, the resilient legs may if desired be formed separately and attached to the lens body by any suitable means.

It will be understood that the invention can be variously embodied within its scope, as defined by the following claims.

Claims

1. An intraocular implant comprising a lens body and at least one flexible retaining leg extending from the lens body to a distal portion, the distal portion and the lens body having co-operating means to enable the distal portion to be releasably attached to the lens body.

2. An intraocular implant as claimed in claim 1 wherein the co-operating means comprises a portion disposed at the free end of the leg and a portion on the body so positioned that when the free end of the leg is attached thereto, the leg is flexed around the periphery of the body.

3. An intraocular implant as claimed in claim 1 wherein the leg extends from a root portion attached to the lens body to the distal portion terminating in a free end, and wherein means on the periphery of the body between the root portion of the leg and the free end thereof is so positioned that when the leg is flexed around the body to enable the distal portion to be attached thereto, the leg bears against the leg support portion means to thereby control the amount of bending of the leg and to distribute the bending stress throughout a substantial portion of the leg and prevent excessive bending of the leg at the root thereof.

4. An intraocular implant as claimed in claim 3 wherein the leg support means comprises a peripheral wall extending circumferentially around a portion of the lens body.

5. An intraocular implant comprising a lens body at least one resilient leg, the leg having an unrestrained condition in which the leg extends generally tangentially from the lens body and spirals radially outwardly to an inwardly turned end portion, a latching shoulder disposed on the leg, and means on the lens body for receiving the latching shoulder to retain the inwardly turned end portion in engagement therewith.

6. An intraocular implant as claimed in claim 5 wherein the means on the lens body comprises a rib on a peripheral portion of the lens body, and a slot extending generally transversely through the rib, the slot being dimensioned and positioned to receive the inwardly turned end portion when the leg is flexed around the peripheral portion and to retain the leg in the flexed condition, substantially all of the leg, when so engaged with the rib, lying inside the outer circumference of the peripheral portion.

7. An intraocular implant as claimed in claim 6 wherein the rib is so positioned on the peripheral portion that the leg bears against the outer surface of the rib when the leg is flexed inwardly to the latched position.

8. An intraocular implant comprising a lens body, at least one flexible retaining leg, the leg in an unrestrained condition thereof extending from a root portion joined to the lens body and terminating in a free end, the free end having a shoulder facing away from the end, and latch means on the lens body for receiving the shoulder in releasable latching engagement, the latch means being so positioned that when the shoulder is retained by the latch means, the remainder of the leg lies around the periphery of the lens body.

9. An intraocular implant as claimed in claim 8 wherein the shoulder is formed by a laterally enlarged portion at the end of the leg, and wherein the latch means comprises an upstanding rib at the lens body periphery, the rib having a transverse slot positioned to receive the portion of the leg adjacent to the enlarged portion so that the enlarged portion is held on the inside of the rib in the releasable latching engagement.

10. An intraocular implant as claimed in claim 8 or 9 wherein the leg has a proximal portion which is tapered from the root portion to a narrower medial portion and a distal portion of substantially constant width beyond the medial portion, whereby stress in the leg caused by movement of the distal portion is distributed along the proximal portion.

11. An intraocular implant as claimed in claim 8, 9 or 10 wherein the leg in its unrestrained condition is inclined at a slight angle to a plane through the lens perpendicular to the axis thereof, and the inside surface of the rib adjacent to the slot is disposed at an angle to the plane such that the surface is parallel to the shoulder.

12. An intraocular implant as claimed in claim 8, 9, 10 or 11 in which the rib is so positioned that when the leg is flexed inwardly for engagement with the rib, the leg bears against the outside surface of the rib to control the curvature thereof.

13. An intraocular implant as claimed in any one of claims 8-12 wherein the latch means is so positioned circumferentially of the lens body that substantially all of the leg when retained by the latch means lies inside a circle centred on the centre of the lens and having a diameter no greater than the diameter of the lens body.

14. An intraocular implant as claimed in any preceding claim wherein the leg is integral with the lens body.

15. An intraocular implant as claimed in any preceding claim having three of the retaining legs substantially equally spaced around the periphery of the lens body.

16. An intraocular implant substantially as herein described with reference to Figures 1-6 or Figures 7 or 8 of the accompanying drawings.