FOCUSSABLE INTRAOCULAR LENS

Abstract: An intraocular lens that provides accomodation in response to contraction and relaxation of the ciliary body (14). Accomodation is achieved by motion of the lens (10), or of an element (30, 32) of a lens system, alternately toward and away from the fovea. Means (16, 18) are provided for biasing the lens (10), or the movable element (32), toward the fovea so that when the ciliary body (14) contracts it counters the bias and causes the lens (10) to move away from the fovea toward the cornea.

Description: FOCUSSABLE INTRAOCULAR LENS Brief Description: This invention relates to a novel intraocular lens that is capable of providing accommodation responsively to contraction and relaxation of the ciliary body. In the normal eye the crystalline lens is self-biasedtoward a spher¬ ical shape, that is, toward maximum r fraction, and for distance view¬ ing it is radially tensioned, andthereby flattened by relaxation of the ciliary body. The lens of the present invention operates on a basically different principle, one generally similar to the usual focussing arrangement in photographic cameras. It achieves accommodation by adjustment of its focal distance, the spacing between the lens and the fovea. The lens is spring biased toward its distance focus position, where it remains so long as the ciliary body remains relaxed. When the ciliary body con¬ tracts it compresses the spring bias, moving the lens away from the fovea to provide accommodation for near viewing. The bias may be supplied by radially extending struts molded integ¬ rally with the lens, which struts extend slightly rearwardly from the lens to engage, or, rather, to be engaged by the ciliary body. When the ciliary body contracts it thus drives the outer ends of the struts radi¬ ally inwardly causing their inner ends to move forwardly, carrying the lens forwardly and thereby increasing its focal distance. Alternative forms of the inventin may include miniature lens sys¬ tems of two or more lens elements in accordance with the designer 's choice. In the usual case only one of the elements of a system is ar¬ / . ranged for movement responsively to the ciliary body, while the other, or others, of the individual elements remain in fixed position. The lens of the invention is preferably placed in the natural cap¬ sule that previously held the crystalline lens, and the zonules are left in place, unless they are somehow damaged, in which case they may be OMPI ~ replaced by an air filled flexible toroid. The capsule serves to hold the lens, and especially the struts, in proper position for engagement by the ciliary body. As in the usual modern practice only a portion of the front wall of the capsule is removed, and a small window is cut in its rear wall. The struts extend to the perimeter of the capsule, and the entire structure is retained by the capsule. Detailed Description: Representative embodiments of the invention will now be described in detail in conjunction with the drawing, wherein: Figure 1 is a cross sectional view of an intraocular lens in accord¬ ance with a first embodiment of the invention; Figure 2 is a front elevational view of the lens shown in Figure It Figure 3 is a fragmentary sectional view of an eye in which the lens shown in Figures 1 and 2 has been implanted t Figure 4 is a fragmentary sectional view of an eye in which a lens according to a modified form of the invention has been implanted; and Figure 5 is a fragmentary sectional view of an eye in which the zon- ules have been replaced by an air filled torus. Referring now to Figures 1 , 2, and 3, the lens according to the first embodiment of the invention comprises a central refractive element 10 about six millimeters in diameter and having a refractive power se¬ lected by the surgeon to provide normal distance vision when it is im¬ planted in the capsule 12 and the ciliary body is relaxed. Radially extending struts 16 are molded integrally with the refractive element 10 and are terminated at their outer ends by any desired blunt abutment means such as the arcuate rim portions 18 illustrated. The struts are just long enough so that the terminations 18 are in light pressure con¬ tact with the perimeter of the capsule 12 when the lens is implanted in the eye 20. The struts lie at an angle to the central plane of the refractive element 10 so that the terminations 18 lie slightly closer to the fovea when the lens is implanted than does the refractive element 10. As indicated by the dashed lines in Figure 3, when the ciliary body 14 contracts, as it normally does when the eye tries to focus on a nearby object, it drives the outer ends of the struts 16 radially inwardly, thereby forcing the lens 10 forwardly, away from the fovea, and, as the ciliary body relaxes the struts act as springs to retract the refractive element 10 back to its original position for distance focus. It is preferred to make the refractive element 10 as small as is practicable, that is, as small as is needed to admit enough light for practical vision. This is to minimize resistance to motion of the re¬ fractive element by the aqueous humour, or by the saline solution that may replace it. It is presently thought that about six millimeters diameter is close to the optimum size. An intraocular system comprising two lens elements 30 and 32, respectively, according to the invention is illustrated in Figure 4. It comprises a posterior lens element 30 of significantly smaller diameter than the capsule 12. It is positioned centrally within the capsule 12 in contact with the posterior wall thereof. It remains in position because of the smallness of forces available to dislodge it as compared to its natural adherence to the capsule wall. The second element 32 lies in the anterior chamber of the eye, and is generally similar to the lens 10 shown in Figures 1, 2, and 3, being supported on struts 34 that extend rearwardly and radially outwardly through the fornix in the anterior wall of the capsule 12 into engage ment with the perimeter of the capsule. The powers of the lenses 30 and 32, and the initial spacing between them are selected by the optical designer to provide the desired focussing action in response to motion of the movable lens 32. A large variety of choices is available. As shown in Figure 5, the zonules 40 (Figures 3 and 4, and not shown in Figure 5) may be removed and replaced by an air filled torus 42 that acts as a cushion between the lens 10 and the ciliary body 14, and also serves to keep the lens 10 in proper position relative to the ciliary body. The torus 42 may be made of any flexible and impervious sheet material that is compatible with body tissues and fluids. * \

Claims: WHAT IS CLAIMED IS: 1. An intraocular lens capable of providing aαxmmodation cαπpris- ing a lens element, and spring biasing means operative between said lens element and the ciliary body when the lens element is implanted for alternately moving the lens element toward a first position relative to the fovea when the ciliary bocty is relaxed and toward a second posi¬ tion farther frαn the fovea in response to contraction of the ciliary body. 2. An intraocular lens in accordance with claim 1 wherein said spring biasing means comprises struts extending radially outwardly frαα said lens element toward the ciliary body and rearwardly so that their outer ends lie closer to the fovea than does said lens element, the angle between the lengths of said struts and the central plane of said lens being resiliently yieldable in response to contraction of the ciliary bcdy. 3. An intraocular lens according to claim 1 wherein said lens element and said spring biasing means are arranged for implantation within the capsule that holds the crystalline lens in the normal eye. 4. An intraocular lens system capable of providing ac__X-__-nodat_ion cαπprising a first lens element for implantation in fixed position in the eye r a second lens element to be spaced frαn said first lens element along the main optical axis of the eye, and spring biasing means oper¬ ative between said second lens element and the ciliary body when the second lens element is implanted for alternately moving said second lens element toward a first position along the optical axis when the ciliary bocty is relaxed and toward a second position when the ciliary body con¬ tracts, the optical specifications of said lens elements being selected so that the focal length of the system is longer when said second element is toward said second position than when it is toward said first position. 5. An .intraocular lens system according to claim 4 wherein said first lens element is arranged for implantation within the capsule of the eye against the posterior wall thereof, said second lens element and said spring biasing means are arranged for implantation in the anter¬ ior chamber with said spring biasing means extendi g into the capsule and engaging the perimeter thereof, and said second position of said second element is farther from the fovea than said first position.

Inventors: LEVY CHAUNCEY F, LEVY, CHAUNCEY, F.
Applicants: LEVY CHAUNCEY F, LEVY, CHAUNCEY, F.
Application year: 1983
Main classification: A61F1
IPC codes: A61F2