WO1992014421A1

WO1992014421A1 - Halo-reducing ophthalmic lens for small incision implant surgery

Info

Publication number: WO1992014421A1
Application number: PCT/US1992/001340
Authority: WO
Inventors: Dennis T. Grendahl; Fritz D. Harnsberger; David R. Foehl
Original assignee: Grendahl Dennis T
Priority date: 1991-02-21
Filing date: 1992-02-20
Publication date: 1992-09-03

Abstract

An ophthalmic prosthetic lens or device (10), particularly, an intraocular lens, for small incision implantation which significantly reduces glare or 'halo' is disclosed. The device comprises a lens body or optic (20) comprising material having a first transmissivity, the lens body having disposed about or around its outer perimeter a layer or coating (22) of a material having a second, lower transmissivity. The layer or coating (22) is of a minimal radial thickness to significantly reduce optical glare or 'halo' due to incident light. In a preferred embodiment, the transmissivity of the lens body (20) to visible light is in the range of 60 % to 100 %, preferably about 80 % to 95 %. The transmissivity of the coating or layer (22) to visible light is in the range of about 0 % to about 40 %, preferably about 5 % to about 25 %. In another preferred embodiment, the lens body (20) is substantially colorless and the layer or coat (22) is intensely blue.

Description

HALO-REDUCING OPHTHALMIC LENS FOR SMALL INCISION IMPLANT SURGERY

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Cross Reference to Related Application This application is a continuation-in-part of Patent application Serial Number 07/659,573, filed 02/21/91, now abandoned.

Background of the Invention Field of the Invention

This invention relates to ophthalmic prosthetic devices or lenses which significantly reduce glare or halo experienced by a patient subsequent to lens implant surgery. More particularly, the present invention relates to intraocular lenses, especially smaller-sized, posterior chamber intraocular lenses, which are implanted in the eye through minimally sized surgical incisions. This technique is sometimes referred to as small incision surgery. Yet more particularly, this invention relates to intraocular lenses which reduce glare associated with incident light by means of a thin coating or layer of low light transmissivity material located substantially on the edge or perimeter of the lens body.

The lenses of human and animal eyes are subject to damage by physical or other external trauma whether accidental or otherwise and by the formation of cataracts. It has been common practice for many years to remove surgically such damaged lenses. An eye with the lens removed is said to be in the aphakic condition.

Subsequent to lens extraction, the aphakic eye does not have the same ability to focus light with the result that the retina receives only a blurred image. Contact lenses, spectacles or a combination of the two have been used in the past with varying degrees of success to focus the light rays on the retina to restore vision. The use of contact lenses and eye glasses to overcome aphakia is subject to the fundamental drawback that such devices are located external to the eye. The use of such external devices results in a shift of the optical center from its normal position within the eye to outside the eye. This can result in distortions and/or changes in the size of the image.

Cataracts are the most common disorder of the eye and are the second leading cause of blindness in the

United States. A cataract is a biochemical change in the structure of the lens of the eye which causes transformation of the normally transparent lens to a cloudy or opaque state. The function of the lens is to focus light rays to form an image on the retina.

Cataracts interfere with the focusing of the light rays causing the image to become^* blurred, and eventually, leading to blindness if unattended. The opacity caused by cataracts are often not distributed uniformly so that the lens has both opaque and transparent zones or regions. Thus, the resulting loss of vision depends upon the size, the location, and the densities of the lens opacities.

A cataract is treated surgically under local anesthesia, in which the cataractous lens is removed. This procedure is one of the most common operations performed by ophthalmic surgeons. During the operation, the surgeon views the operation site through a high powered microscope to facilitate the procedure. The eye normally is kept moist with physiological saline throughout the procedure.

Standard procedure for removing the damaged lens involved first dilating the pupil and then making a half circle incision at the junction of the sclera and the clear cornea i.e, in the conjunctive and limbus. The upper half of the cornea was retracted, as was the iris, to provide access to the lens. The lens was then removed by one of several techniques. For example, phaco- emulsification involves the ultrasonic fragmentation of the lens into small particles. Once phaco-emulsification has been accomplished, the particles are removed by aspiration leaving a clean lens capsule free from cataractous material. The instrumentation used in phaco-emulsification permits the length of the surgical incision to be as little as 3mm or less. Provided the implanted lens is of a similar size, less traumatic lens implantation surgery through smaller surgical incisions is possible.

In view of the less traumatic nature of small incision implant surgery, smaller diameter intraocular lenses continue to be developed. Unfortunately, as the diameter of the intraocular lens decreases, the likelihood increases that the edges of the lens will be exposed to incident light passing through a dilated iris.

When this occurs, an edge glow or halo becomes visible to the patient wearing the lens. If the entire perimeter of the IOL is exposed to the incident light path through the iris, a full, circular halo may be seen by the patient.

This circular halo or glare is potentially disturbing to the patient, and generally is to be minimized or eliminated.

Description of the Related Art

United States Patents No. 4,676,791 and 4,774,036 are patents to William LeMaster et al. which disclose intraocular lenses having a lens body with a clear or colorless central lens portion or region and a peripheral lens portion or region having a reduced, or graded transmissivity. As shown, Figures 1 and 2 of the '791 patent contemplate a colored ring or rim portion designated 22. The colored ring or rim of LeMaster comprises a portion of the optic body. While the width of the color ring of LeMaster is not stated, it is evident from the '791 and '036 patent disclosures, that the colored ring or zone of the lens is wide enough so as to be created by the potentially cumbersome process of coextrusion of the central colorless portion of the lens body into or over the colored zone (Column 3 of the '036 patent). LeMaster et al. make no mention of small incision surgical implantation. Moreover, the teaching of LeMaster would not likely be referred to by one of skill in the small incision lens art because lacking disclosure relating to small incision surgery, large incision surgery would be implied. The substantially opaque, colored ring or rim of LeMaster et al. could be understood to be too wide to produce a small incision lens having a colorless, transparent, central optical zone which is wide enough to focus sufficient incident light on the retina.

U.S. Patent 3,454,332 to R. Siegel discloses a corneal plastic contact lens with a multiplicity of colored peripheral zones. The colored zones of Siegel radiate from a central colorless zone. U.S. Patents 4,596,578 and 4,605,409 both to Charles

D. Kelman disclose intraocular lenses which can be inserted through incisions which are less than 5mm. in length. The Kelman patents disclose a masking means which overlies a peripheral marginal portion of the lens body or optic to prevent glare. In the '409 patent, the masking means is deformable between an expanded condition and a retracted condition.

U.S. Patent 4,556,998 to Steven B. Siepser discloses an intraocular lens comprising a hydrophilic material which is capable of expanding in dimension by absorption of natural eye fluid. The Siepser lens, when implanted, has a small diameter and, after absorbing eye fluid, expands to a larger diameter. Siepser '998, the disclosure of which is incorporated by reference herein, extensively discusses prior art intraocular lenses and the advantages of less traumatic, small incision implant surgery.

None of the above United States Patents, alone or in combination, disclose or suggest the present invention.

Summary of the Invention

Briefly, in one aspect, the present invention is a glare-reducing or halo-reducing ophthalmic lens or intraocular lens capable of being implanted with small incision implant surgery, the lens comprising a lens body or optic having a transmissivity, for visible light, in the range of about 60% to about 100%, preferably, about

80% to about 95%. The optic has, on its perimeter, a layer or coating of a material having a transmissivity to visible light in the range of about 0% to 40%, preferably, about 5% to 25%. The coating of this invention has a minimal radial or lateral thickness or annular width which significantly reduces glare due to light impinging upon and being transmitted through the lens body. The perception of the lens implant patient is the best indicator of whether glare reduction has been significant.

In a preferred embodiment of the present invention, the lens body or optic is substantially colorless and the layer or coating is an intense, substantially opaque or non-visible-light-transmissive blue.

In yet another embodiment of the present invention, the optic of the present invention further comprises positioning loops or haptics. The haptics of this invention may, in the user's preference, comprise a low transmissivity material (e.g., a colored material), or a high transmissivity material, (e.g., a colorless material). In yet another preferred practice of the present invention, the optic or lens body has a sufficiently small diameter so as to permit it to be inserted or implanted using small incision implant surgical techniques. Generally this means that lenses of this invention can be implanted through an incision in the eye of 6mm or less, in length. Preferably, lenses of this invention have a diameter which permits them to be implanted through surgical incision of less than 5.5mm in length, preferably lens than 5.0mm.

"Visible light" herein means light having a wavelength in the range of about 400nm to 800nm.

The terms "coating" or "layer" of a low transmissivity material are used extensively in the present application. These terms are intended to be used so as to distinguish from a substantially thicker ring, zone, or region of a colored material. As an example, a coating or layer, as those terms are used herein, may have a radial thickness or width in the range of from about 2 to 3 dye molecule diameters up to about 250 microns. The radial thickness of the coating is preferably less than about 10 microns and most preferably less than about 1 micron. It is also to be understood that the terms "coating" or "layer" refer to materials which lie on the surface of the lens optic that is, which are not part of the optic at all, or which permeate into the bulk of the optic only to the extent necessary to provide adherence thereto. For example, a suitably biocompatible and opaque dye for use in this invention may permeate a short distance into the lens body. Whether the low transmissivity material is coated on the perimeter of the lens optic and stays on its surface or slightly permeates therein, the minimum thickness and annular width of the coating is that which will restrict transmission of incident light from the lens perimeter through the coating to the body of the lens optic and vice versa. By this expedient patient or user glare or "halo" is reduced or eliminated. As noted, this invention is particularly applicable to lenses of a diameter which makes them suitable for small incision surgery.

Brief Description of the Drawing

Fig. 1 illustrates a top view of an intraocular lens according to the present invention;

Fig. 2 illustrates a sectional view of the intraocular lens depicted in Fig. 1 taken along line 2-2;

Fig. 3 is a top view of an embodiment of the present invention wherein the lens optic is polygonal. Detailed Description of the Invention

Fig. 1 illustrates an intraocular lens 10 of the present invention including a lens body or optic 12 and two positioning loops or haptics 14 and 16. The lens optic 12 includes an essentially clear or colorless lens body 20 having on its edge or perimeter a colored coating or layer 22. The entire assembly is made of any biocompatible material having suitable optical characteristics. While described with respect to intraocular lenses, other ophthalmic lenses, such as corneal inlays, also may use this invention.

Preferably, polymethymethacrylate (PMMA), or other ophthalmic lens materials such as polysulfone, polythersulfone or polycarbonate are utilized to manufacture lens bodies.

The colored layer 22 is sufficiently darker in color to substantially reduce the intensity of visible light transmitted from lens body 20 to or through colored layer

22. For example, it may have a visible light transmissivity of about 0% to 40%, with a preferred range of about 5% to about 25%. While the transmissivity of layer 22 is preferably reduced by coloring it with a color darker than the transparent section, such as blue, the transmissivity can be reduced by other known processes as well. The annular width of the coating 22 is selected to provide adequate space for the attachment of the loops 14 and 16. Haptics may be added by known processes such as staking, adhesive bonding, or ultrasonic bonding. The annular width of lens 10 is also sufficient to provide adequate reduction in the intensity of the light transmitted from the periphery to the central portion of the lens 10 (and vice versa) .

Loops 14 and 16 optionally may be made of colored material. This further reduces the intensity of the light transmitted to the clear central portion 20. Alternatively, the loops 14, 16 can be made of a colorless material similar to that used in the lens body 20. The same discussion applies to intracorneal lens edge effects. Positioning holes or locating holes (not shown) optionally may be provided in the optic body 12.

The lens body or optic 12 of this invention has a transmissivity to visible light in the range' of about 60% to about 100%, preferably about 80% to 95%. Transmissivity is measured using known methods. In a preferred practice, the lens body is also substantially clear, or more precisely, colorless. It is contemplated that lens body 12 will have the requisite transmissivity and yet not be colorless. For example, an ultraviolet absorptive material may be included in the lens body composition. Such a material may impart a color, e.g., yellow, to the lens body and slightly to substantially reduce its visible light transmissivity.

Fig. 2 shows a sectional view of the lens of Fig. 1 taken along the line 2-2. The colored portion, layer, or coat 22 extends annularly from the rear surface of the lens 24 to the front surface of the lens 26, that is, from rear edge 28 to front edge 30. While it is not necessary that the entire edge of the lens body be coated, the edge must be sufficiently coated to reduce the halo effect discussed above.

Fig. 3 shows an optional polygonal shape for lens body or optic 12. Optic 12 of Fig. 3 is octagonal. Many other lens shapes are possible within the contemplation of the present invention. As shown, coating or layer 22 is located substantially along the entire outer perimeter or edge of lens body 20.

As noted above, lenses of this invention are implanted using small incision surgical techniques.

"Small incision implant surgery" as the term is used herein generally means implantation of an artificial ophthalmic prosthetic device, such as an intraocular lens, through a surgical incision which is less than about 5.5mm in length and which is preferably less than about 5.0mm in length. Because of the curvature of the eye and the elasticity of eye tissue, a lens capable of being implanted via small incision implanted surgery can have a diameter of about 0.5mm greater than the length of the incision through which it is to be inserted. Thus for example, a lens implantation using small incision techniques can have a diameter of about 6.5mm or less and preferably less than about 6.0mm. Most preferably, a lens of this invention will have a diameter of less than about 5.0mm. This is to be contrasted with the diameter of prior art lenses used in large incision implant surgery where incisions of 7.0mm and up to 12.0mm or longer (the lenses being proportionately sized) were necessary.

There are many possible techniques which may be used to impart coating or layer 22 to the edge of optic body

12. For example, lens body or optic 12 may be completely masked with the exception of its edges. The masked optic may then be dipped into a suitable solution of a low transmissivity, generally colored, material. This technique would be used when it is desired to have a very thin layer or coating of colored material. For example, a solution of methylene chloride, a dye, such as green dye number 3, and the polymeric material of which lens body 12 is comprised may be prepared. It is desirable to use some proportion of the lens body polymer in the solution to restrict possible erosion of the lens body itself when it is dipped in the colored solvent solution.

The masked lens is then dipped in the above solution and the solvent permitted to evaporate. This preparative technique provides a very thin layer of colored material with minimal penetration of the colored material into the lens body. For example, colored material may penetrate radially into the lens body as little as the diameter of two or three dye molecules. Removal of the mask subsequent to evaporation of the solvent produces an intraocular lens of the present invention.

In another preparative technique, a mixture of a powdered pigment, for example, copper blue, a solvent, such as methylene chloride, and a mixture of methylmethacrylate monomer and polymethymethacrylate is prepared. In this preparative route, rather than masking, as noted above, the above mixture is precision painted or rolled onto the edge of the optic. This rolling or painting step may be accomplished using commercially available precision application equipment.

The solvent may then be evaporated either at room temperature or elevated temperature if processing time is to be shortened. By means of this application technique, a continuous, dense colored coating is applied to the edge of the optic body.

In yet a third preparative route, a thin, e.g., about 0.01mm to about 0.1mm, sheet of highly pigmented polymethymethacrylate (PMMA) sheet is wrapped around a central optic core of substantially colorless polymethymethacrylatehavingtherequiredtransmissivity.

The sheet of colored PMMA then is securely anchored or bonded to a tube or rod of lens core material, e.g., by heating. The lens body then is machined or sliced from this composite structure. Optional haptics may then be added by conventional techniques discussed above.

As noted above, this invention is particularly applicable to intraocular lenses. Anterior chamber and posterior chamber lenses are within its scope. The glare or halo reduction characteristics of other ophthalmic lens prostheεes, e.g., intracorneal inlays, or corneal lenses, may be enhanced by application of this invention.

The above disclosure will suggest many alterations and variations to one of ordinary skill in this art. This disclosure is intended to be illustrative and not exhaustive. All such variations and permutations suggested by the above disclosure are to be included within the scope of the attached claims.

Claims

What is claimed is as follows:

1. An ophthalmic lens capable of implantation with small incision implant surgery comprising: an optic body comprised of a material having a transmissivity in the range of about 60% to about 100%; said body having on its outer perimeter: a layer of a material having a transmissivity in the range of about 0% to 40%, said layer lying on the outer perimeter of the optic body and having a radial width of up to about 250 microns and which substantially reduces glare due to light impinging on the optic body.

2. A lens according claim 1 which further comprises positioning loops securely attached to the perimeter of said optic body through said layer.

3. A lens according to claim 1 wherein said optic body is polygonal.

4. A lens according to claim 1 wherein said optic body is colorless.

5. A lens according to claim 1 wherein said layer comprises a substantially opaque blue material.

6. A lens according to claim 1 wherein the optic body has a diameter of less than 6.5mm.

7. A lens according to claim 1 wherein the optic body has a diameter of less than 5.0mm.

8. An intraocular lens for implantation in a patient's eye with small incision implant surgery, the lens comprising: an optic body comprised of a material having transmissivity to visible light in the range of about 60% to about 100%, said body having on its outer perimeter: a layer of a material having a transmissivity to visible light in the range of about 0% to 40%, said layer having a minimum radial thickness which substantially reduces glare due to light impinging on said optic body .

9. An intraocular lens according to claim 8 which further comprises positioning loops securely attached to the perimeter of said optic body through said layer.

10. An intraocular lens according to claim 8 wherein said optic body is polygonal.

11. An intraocular lens according to claim 8 wherein said optic body is colorless.

12. An intraocular lens according to claim 8 wherein said layer comprises a substantially opaque, blue material.

13. An intraocular lens according to claim 8 wherein the optic body has a visible light transmissivity in the range of 80% to 95%

14. An intraocular lens according to claim 8 wherein the layer has a transmissivity to visible light in the range of about 5% to 25%

15. A glare-reducing intraocular lens for implantation in the eye of a patient with small incision implant surgery, the lens comprising: a substantially colorless lens body, said body having on its outer perimeter a layer of a colored material, said layer lying on the outer perimeter of the optic body and having a radial thickness which reduces glare due to light impinging upon said body.

16. An intraocular lens according to claim 15 wherein said layer has a radial thickness in the range of less than about 250 microns.

17. An intraocular lens according to claim 15 wherein said layer is a blue material.

18. A method of making a glare reducing ophthalmic prosthetic device comprising the step of: a. providing a lens body having a transmissivity to visible light in the range of about 60% to 100%; and b. coating the edge of the lens body with a material having a transmissivity to visible light in the range of about 0% to 40%.

19. A method according to claim 18 which further includes the step of mounting lens support structures on said lens body.

20. A method according to claim 18 wherein the device is an intraocular lens.

21. A method acceding to claim 20 which further includes the step of mounting lens haptics on the lens body.

22. A method according to claim 18 wherein the lens body is substantially transparent to visible light and the coating is a substantially opaque blue.