POSTERIOR CHAMBER INTRAOCULAR LENS

Abstract: An intraocular lens (10, 110) for implanting in the posterior chamber of an eye after extracapsular cataract extraction includes a flexible filament ring (24, 124) spaced from a lens body (12, 112) to engage the posterior capsule (134) and adhere thereto due to fibrosis attachment forming a barrier enclosing an optical zone behind the lens body (12, 112) to prevent migration of crystalline, epithelial cells from the perimeter of the posterior capsule (134) to the optical zone thereby preventing opacification.

Description: POSTERIOR CHAMBER INTRAOCULAR LENS BACKGROUND OF THE INVENTION I . Technical Field The present invention pertains to intraocular lenses and more particularly to intraocular lenses for implanting in the posterior chamber of the eye after extracapsular cataract extraction. II. Discussion of the Prior Art The implanting of intraocular lenses after cataract surgery has become an accepted practice, and there are many intraocular lens designs available for positioning in the anterior chamber or posterior chamber of the eye or for support on the iris. During cataract surgery, it is preferable to extract the lens while leaving the posterior portion of the lens capsule intact to pro- vide a barrier to prevent movement or loss of the vitreous which fills the eye behind the lens. If the lens is re¬ moved intact with the capsule, referred to as intracap- sular cataract extraction, the vitreous can move through the pupil causing vitreous loss and increasing the chances of complications, such as glaucoma, corneal opacity, dis¬ placement of the intraocular lens, retinal hemorrhage, holes, breaks and detachment., and cystoid macula edema. In many cases after extracapsular cataract ex¬ traction and implant of an intraocular lens, the posterior capsule becomes opacified due to migration of crystalline, epithalial cells into the optical zone behind the lens which, clustered, form Elschnig*s pearls. This opacifi- cation of the posterior capsule, referred to as second¬ ary cataract, occurs in a large percentage of extra¬ capsular cataract extractions and is a primary cause of post operative complications. The procedures to remove the secondary cataract include descission using a needle or scissors to punch or cut a hole in the posterior cap¬ sule and the use of a laser focused through the pupil to open the posterior capsule. While the posterior cap- sulotomy removes the opacification to improve sight, it carries with it the adverse effects discussed above with respect to intracapsular cataract extraction relating to the removal of the barrier to vitreous movement. Accordingly, there is a great need for a manner in which to prevent opacification of the posterior capsule to permit optimal use of intraocular lenses for replace¬ ment of natural lenses. U.S. Patent Re. 31,626 to Hoffer discusses an intraocular lens having a lens body with a unitary, rearwardly projecting, substantially annular ridge or lip to seat against the posterior capsule. It is indicated that the lip may serve as a barrier to mi¬ gration of cells and fiber development; however, since the implanted intraocular lens has less volume than the removed natural lens, the posterior capsule is " normally wavy and wrinkled preventing the lip from complete engage¬ ment with the posterior capsule. Additionally, with age the capsule becomes more wrinkled and the zonules lose elasticity. Since the lip is rigid, it will not become attached to the posterior capsule in the manner that the pliant hairs are fixed by fibrosis in the capsule fornix region. SUMMARY OF THE INVENTION It is, accordingly, a primary object of the present invention to overcome the above-mentioned defi¬ ciencies of the prior art by producing a ring of fibrosis around the optical zone of a posterior capsule after extracapsular cataract extraction to prevent migration of crystalline cells into the optical ..zone and thereby prevent clouding or opacification. Another object of the present invention is configure an intraocular lens to have a flexible filament ring extending from the lens body to engage the posterior capsule after implant in the posterior chamber to promote fibrosis producing a barrier to crystalline cell migration. The present invention has another object in the design of an intraocular lens preventing secondary cata¬ ract and stabilizing the lens body centrally of the iris by adhesion of a ring to the posterior capsule. An additional object of the present invention is to obviate the need to open the posterior capsule after extracapsular cataract extraction and implant of an in¬ traocular lens by preventing migration of crystalline cells into the optical zone and thereby preventing opacification or secondary cataract. Some of the advantages of the present invention over the prior art are that the intraocular lens of the present invention facilitates implant by the surgeon, is flexible to compensate for wrinkles and waves in the posterior capsule, adheres to the posterior capsule to positively centralize the lens body behind the iris, creates through the natural process of fibrosis a barrier. to crystalline cell migration and is relatively inexpen¬ sive to manufacture. The present invention is generally characterized in an intraocular lens for implanting in the posterior chamber of the eye including a lens body, fixation means extending from the lens body to engage portions of the eye in the posterior chamber and bias the lens body to¬ ward the posterior capsule of the eye, and a flexible ring extending rearwardly from the lens body to engage the posterior capsule completely enclosing an optical zone of the posterior capsule behind the lens body whereby the flexible ring creates fibrosis to produce a barrier to migration of crystalline cells into the optical zone. The present invention is further generally characterized in a method of preventing opacification of the posterior capsule of the eye after extracapsular cataract extraction comprising the steps of positioning an intraocular lens in the posterior chamber of the eye, the intraocular lens having a lens body and a flexible ring extending therefrom, and biasing the flexible ring against the posterior capsule to create fibrosis and form an enclosing fibrosis-created barrier around an optical zone behind the lens body to prevent migration of crystalline cells into the optical zone. Other objects and advantages of the present invention will become apparent from the following descrip- tion of the ' preferred embodiments taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a top plan view of an intraocular lens in accordance with the present invention. Fig. 2 is a side view of the intraocular lens of Fig. 1. Fig. 3 is a top, plan view of another intra¬ ocular lens in accordance with the present invention. Fig. 4 is a side view of the intraocular lens of Fig. 3. Fig. 5 is a partial section of an eye with the intraocular lens of Fig. 3 implanted after extracapsular cataract extraction. DESCRIPTION OF THE PREFERRED EMBODIMENTS An intraocular lens in accordance with the pre¬ sent invention is illustrated in Figs. 1 and 2 and includes a lens body 12 constructed of a clear plastic, such as polymethylmethacrylate, lathe cut or molded to have a desired configuration. As shown, lens body 12 has con¬ vex front and rear surfaces 14 and 16, respectively; and, fixation elements in the form of flexible loops 18 and 20 are secured in bores in opposite sides of the lens body and extend away from the periphery of the lens body and upward away from the rear surface 16. The loops are made of a very flexible material such as polypropylene and have free ends to engage the sulcus or the posterior capsule when the intraocular lens is implanted in the posterior chamber with the loops being compressed to permit the intraocular lens to adapt to eyes of varying dimenstions. A positioning hole 22 is disposed in the front surface 14 of the lens body to facilitate maneuver¬ ing of the intraocular lens by the surgeon. As thus far described, the intraocular lens is conventional; and, it will be appreciated that the lens body and the loops of intraocular lenses in accordance with.the present invention can have any desired configurations. Attached to the lens body 12 in accordance with the present invention is a flexible ring 24 formed of an annular filament 26 spaced from the rear surface 16 of the lens body and attached to the periphery of the lens body by diametrically opposed struts 28 and 30. The struts are staked in bores in the periphery of the lens body and are angled away from the lens body such that the annular filament 26 is spaced laterally from the peripheral edge of the lens body as well as being spaced rearwardly from the rear surface of the lens body. The ring 24 is made of very flexible filaments of ma¬ terial that promotes fibrosis when contacting the pos¬ terior capsule, such as polyprooylene. As will be explained in more detail hereinafter, the ring must be sufficiently flexible to engage the posterior capsule at all points even when the capsule is wavy and wrinkled such that a complete ring formed by fibrosis is obtained. The term "ring" as used herein is not meant to be limi¬ ted to an annular shape but rather is meant to include any configuration producing an enclosing border or frame around the optical zone of the lens body, for example, elliptical or regularly or irregularly polygonal. The power of the lens body can range from -6 to +30 diopters; and in one exemplary embodiment, the diameter of the lens body is 7 mm, the filaments of the flexible ring and the loops are 0.15 * mm in diameter, the diameter of the ring formed by the annular filament is 8 mm (i.e., greater than the diameter of the lens body), the ring formed by the annular filament is spaced 0.5 mm from the rear surface of the lens body, the length from end to end of the loops is 14 mm, and the loops extend away from the lens body at an angle of 10 °. Another embodiment of an intraocular lens 110 ciccording to the present invention is illustrated in Figs. 3 and 4 and is formed of a lens body 112 having a convex front surface 114 and a planar rear surface 116 with oppositely extending fixation elements or loops 118 and L20 having a greater radius of curvature than the loops of intraocular lens 10. The lens body 112 and the loops 118 and 120 are formed integrally of polymethylmetha- cryla e as one piece, and a pair of diametrically opposed positioning holes 122 are disposed in the front surface of the lens body. The differences in construction and configuration of the lens bodies and loops of the embodi¬ ments of Figs 1 and 3 are shown to illustrate that the flexible ring according to the present invention can be used with various types of intraocular lenses. The flexible ring 124 of the intraocular lens 110 is formed of two 180° arcuate filament segments 126a and 126b each having upwardly and inwardly extending legs or struts 128 and 130 at opposite ends thereof to be received in bores in the rear surface 116 of the lens body such that the ring formed by segments 126a and 126b is spaced behind the rear surface 116 and laterally from the periphery of the lens body producing an enclosing border or frame around the optical zone of the lens body. The flexible ring filaments are made of very flexible material enhancing fibrosis, such as polypropylene, to provide 360° contact with the posterior capsule, as men¬ tioned above; and, the legs 128 and 130 are positioned adjacent each other, preferably abutting, such that the fibrosis barrier produced by the ring is continuous with no gaps, the fibrosis filling any interstice between the segments. The intraocular lens 110 can have a wide range of powers as mentioned above; and, in an exemplary em¬ bodiment, the diameter of the lens body is 7 mm, the fila- ments of the flexible ring are 0.15 mm in diameter, the diameter of the flexible ring formed by the segments 126a and 126b is spaced 0.1 mm from the rear surface of the lens body, the length from end to end of the loops is 14 mm and the loops extend away from the lens body at an angle of 9°. Intraocular lens 110 is illustrated in Fig. 5 implanted in the posterior chamber of the eye after ex¬ tracapsular cataract extraction, the ends of loops 118 and 120 being seated in the sulcus 132. The angle of the loops 118 and 120 forces the flexible ring 124 against the posterior capsule 134 such that the filaments 126a and 126b engage the capsule at all points, the flexible nabure of the filaments enabling contact of the ring with the capsule at all points even though the capsule is wavy and wrinkled. While the loops are shown posi¬ tioned in the sulcus, the loops can also be positioned in the cjpsule if desired, it being of primary interest only that the flexible ring is biased against the posterior capsule. Once the intraocular lens is in place after extracapsular cataract extraction, fibrosis will develop around the filaments securing the ring to the capsule and forming a continuous barrier around the optical zone of the lens body. Fibrosis is the reaction by the body to a foreign object and involves the formation of col¬ lagen fibers or scar tissue which grow around the foreign object. Due to the use of filaments to engage the cap¬ sule, the fibrosis will attach to the ring, and it is the fibrosis that forms, with the ring, the continuous barrier on the capsule. It is important to note that fibrosis will not attach to rigid solid objects, such as the ridge in the Hoffer patent Re. 31626, to form a bar¬ rier. With the intraocular lens implanted, the fibrosis- formed ring prevents migration of crystalline, epithelial cells along the capsule from the perimeter into the opti¬ cal zone circumscribed by the ring thereby preventing clustering of cells to form Elschnig's pearls and main¬ taining the capsule transparent. Thus, the necessity for opening the capsule, by descission or laser, is mini¬ mized and complications resulting from opening of the capsule are avoided. The specific examples discussed above of intra¬ ocular lenses according to the present invention are parti- cularly useful for patients suffering from high myopia in that the 7 mm lens body facilitates centering and the extremely flexible loops are better tolerated by the sensitive tissue of the high myope. High myopia is one of the principal causes of cataracts; and, thus, it is important that lenses be designed to be implanted in -patients with hgih myopia. By the use of a flexible ring on an intraocular lens in accordance with the present invention, there is provided an- effective means and method to prevent opaci¬ fication of the posterior capsule after extracapsular cataract extraction; and, additionally, the adhesion of the ring to the posterior capsule stabilizes the intra¬ ocular lens in the eye. The lens body and the fixation means of the intraocular lens can have any desirable con¬ figurations in accordance with the present invention, it being of primary importance only that fixation of the intraocular lens in the posterior chamber places the flexible ring in contact with the posterior capsule to create a complete ring of fibrosis. As noted above, the filamentous material of the flexible ring is of a nature to promote fibrosis and cause the ring to adhere to the capsule producing a bar¬ rier to cell migration and also causing the lens body to be stabilized in a central position behind the iris. The adhesion of the ring to the capsule can be enhanced by providing the filaments with an irregular surface. Materials known to be effective in promoting fibrosis to adhere the ring to the capsule include filaments of polypropylene or polymethylmethacrylate; however, the filaments could also be treated or coated with a material to enhance the process of fibrosis. Inasmuch as the present invention is subject to many variations, modifications and changes in detail, it is intended that all matter described above or shown in the accompanying drawings be interpreted as illustra- tive and not in a limiting sense.

Claims: WHAT IS CLAIMED IS: 1. An intraocular lens for implanting in the posterior chamber of the eye comprising: a lens body; fixation means extending from said lens body to engage portions of the eye in the posterior chamber and bias said lens body toward the posterior capsule of the eye; and a flexible ring extending rearwardly from said lens body to engage the posterior capsule completely enclosing an optical zone of the posterior capsule behind said lens body whereby said flexible ring creates fib¬ rosis to produce a barrier to migration of crystalline cells into the optical zone. 2. An intraocular lens as recited in claim 1 wherein said flexible ring is circular and has a diameter greater than the diameter of said lens body. 3. An intraocular lens as recited in claim 1 wherein said flexible ring is spaced laterally from the peri- phery of said lens body. 4. An intraocular lens as recited in claim 1 wherein said flexible ring is made of polypropylene filaments. 5. An intraocular lens as recited in claim 1 wherein said flexible ring is made of flexible filamentous ma- terial capable of promoting fibrosis. 6. An intraocular lens as recited in claim 1 wherein said flexible ring is made of a plurality of arcuate filament segments secured to said lens body with ends closely adjacent to permit fibrosis to form a continu¬ ous barrier without gaps. 7. An intraocular lens as recited in claim 1 wherein said fixation means includes filament loops angling away from a rear surface of said lens body. 8. An intraocular lens as recited in claim 1 wherein saif flexible ring is constructed to adhere to the posterior capsule. '). An intraocular lens as recited in claim 8 wherein said flexible ring is made of flexible material having an irregular surface to enhance adhesion to the posterior capsule. 10. A method of preventing opacification of the posterior capsule of the. eye after extracapsular cataract extrac- tion comprising the steps of positioning an intraocular lens in the posterior chamber of the eye, the intraocular lens having a lens body and a flexible ring extending therefrom; and biasing the flexible ring against the posterior capsule to create fibrosis and form an enclosing fibrosis- created barrier around an optical zone behind the lens body to prevent migration of crystalline cells into the optical zone. 11. An intraocular lens for implanting in the posterior chamber of the eye comprising: a lens body; fixation means extending from said lens body to position said intraocular lens in the posterior chamber of the eye; and filament means forming a flexible ring spaced' from said lens body to engage the posterior capsule pro¬ ducing a barrier enclosing an optical zone on the pos¬ terior capsule behind the lens body. 12. An intraocular lens as recited in claim 11 wherein said filament means is made of a material promoting fibrosis upon engagement with the posterior capsule. 13. An intraocular lens as recited in claim 12 wherein said flexible ring extends around the periphery of said lens body. 14. An intraocular lens as recited in claim 13 wherein said flexible ring is formed of a plurality of arcuate filament segments having adjacent ends secured to said lens body.

Inventors: VERZELLA FRANCO, VERZELLA, FRANCO
Applicants: EPSTEIN ROBERT H, LENS SRL
Application year: 1985
Main classification: A61F1
IPC codes: A61F2