Lense arrangement for vitreoretinal surgery

#The invention relates to a lens arrangement for observation and surgical treatment of the vitreous or retina of the eye, and more particularly for use in vitreoretinal surgery.

#Direct ophthalmoscopy lenses which create a virtual image within the eye and indirect ophthalmoscopy lenses which create a real image outside of the eye are two lens types which have been used for fundus observation and as aids in the surgical treatment of the eye. Known lenses of this type that are used in vitreoretinal surgery are maintained on the eye through the use of a handle that is held by an assistant during the surgery. A problem exists with the use of such a handle in that the assistant may require considerable prior experience in vitreoretinal surgical procedures, and that the exact lens position required may be tiresome as well as difficult to maintain over the course of the surgery, especially if there is some movement of the eye or if some movement of the imaging lens is desired to aid the physician in his work.

#It is also known to hold such lenses in place with the use of a suture down ring. The suture down ring is comprised of metal or other bio-compatible material and has one or more extending fingers or leg portions around which sutures, which have been sewn into the sclera, are tied. The lens, which may be, for example, a plano-concave direct ophthalmoscopy lens or an indirect ophthalmoscopy lens system comprised of two or more elements, slips into the suture down ring and is thereby stabilized and centered over the cornea. Commonly, a sterile interface solution is used in conjunction with the lens to produce an optical interface of the lens with the eye. The suture down ring has been successfully used, but because its use involves a suturing procedure it could be desirably avoided were there to be a suitable non-invasive alternative.

#FIG. 1 is a sectional view of a lens arrangement according to one embodiment of the invention.

#FIG. 2 is a plan view of the contact lens element and flange illustrated in FIG. 1.

#FIG. 3 is a sectional view of a lens arrangement according to another embodiment of the invention.

#Referring to FIG. 1, there is shown a sectional view of a lens arrangement 10 mounted on a cornea 12 of an eye 14. Lens arrangement 10 includes a frusto-conically shaped frame 16 which coaxially fixes a contact lens element 18 relative to an imaging lens 20, which together comprise an indirect ophthalmoscopy contact lens arrangement for creating a real aerial image of a structure in the eye anterior to the cornea of the examined eye. Contact lens element 18 has a concave posterior surface 22 and a convex anterior surface 24. Concave posterior surface 22 has a shape substantially corresponding to the shape of an average cornea and therefore may have an apical radius of approximately 7.0 to 8.5 mm, and preferably may be approximately 7.7 to 7.8 mm. Posterior surface 22 may be spherical or aspherical and may be fitted on the cornea with the use of an interface solution 26 as is commonly known in the art. Referring additionally to FIG. 2 , posterior surface 22 preferably has a cord diameter d of approximately 9-13 mm and is most preferably about 11.7 mm. Anterior surface 24 may have an apical radius ranging from infinity for a planar surface to either a convex or concave radius of approximately 6.0 mm., and may be either spherical or aspherical. Contact lens element 18 has a peripheral region 28 which is connected with a flange 30 around its circumference. Flange 30 extends radically onto the sclera 32 of eye 14. Flange 30 has a posterior surface 34 which has a different curvature from that of posterior surface 22 of contact lens element 18, and more specifically, posterior surface 34 of flange 30 has a curvature substantially corresponding to the curvature of an average sclera of an eye, for example, a 12 mm. radius. Consequently, the curvature of the posterior surface 34 of flange 30 is substantially flatter than the curvature of the posterior surface 22 of contact lens element 18, and as such the lens device tends to be stabilized and centered over the cornea of the eye. Flange 30 has an anterior surface 35 that may have a slope or curvature that provides an adequate thickness of approximately 1.5 mm. to flange 30, thereby providing substantiality and strength to this component. Posterior surface 34 of flange 30 has a outside cord diameter D which may range from approximately 15 mm to approximately 20 mm, and is preferably 16 to 17 mm in diameter. Contact lens element 18 is fixed, for example, by a screw connection (not shown) to the smaller diameter end of frusto-conical frame 16. Imaging lens 20 is fixed at the larger opening end of frusto-conical frame 16 between a shoulder 36 and an o-ring 38, or by other conventional fastening means. Imaging lens 20 is coaxially fixed relative to contact lens element 18 and is preferably biconvex with a power which may be as high as 150 to 170 diopters. Imaging lens 20 is spaced from and cooperates in a known manner with contact lens element 18 for capturing light rays exiting the eye through the cornea and passing through contact lens element 18. Imaging lens 20 focuses such light rays to create a real image of the retina and vitreous anterior to the cornea, and preferably anterior of imaging lens 20. An indirect ophthalmoscopy lens system of this type which includes a contact lens element and one or more imaging lenses is known in the art and is described in detail, for example, in my prior U.S. Pat. No. 5,046,836, which is incorporated herein by reference.

#FIG. 2 is a plan view of contact lens element 18 and flange 30. In this embodiment, contact lens element 18 and flange 30 are made of the same optically transparent material and are integrally connected with one another in peripheral region 28 as a single unit. As can be seen in FIG. 2, flange 30 has four evenly spaced recesses 40 each of which has an opening at the outer periphery 42 of flange 30 and extend radially inwardly toward contact lens element 18. The circumferential extent C of the opening of each recess 40 at the outer periphery 42 may be from about 4 to about 8 mm, and is preferably about 6.75 mm, and each recess 40 extends radially inwardly from an imaginary extension of the outer periphery 42, shown by a dotted line in FIG. 2 in the lower right-hand recess, by a distance "r" of about 1 to about 5.5 mm, and is preferably about 2.15 mm. In general, the recess or recesses are sized to accommodate known dimensions of current surgical tools which penetrate the sclera during vitreoretinal surgery.

#FIGS. 3 and 4 illustrate an embodiment modified from that of FIGS. 1 and 2 wherein a flange 30' constitutes a separate component from that of contact lens element 18' which is fixed in frame 16' coaxially with imaging lens 20. Flange 30', which is shown in plan view in FIG. 4, may be made of metal or any other suitable material which is biocompatible with the eye. In this embodiment, contact lens element 18' presents a circumferential edge 19 which has a diameter the same or just slightly less than the inner diameter of flange 30' so that contact lens element 18' can be slidably received within flange 30' for stabilizing the indirect ophthalmoscopy lens system 10' relative to eye 14. Recesses 40 in flange 30' are sized the same as described in connection with FIG. 2. Flange 30' thus operates in the same manner as flange 30 in FIG. 2 to stabilize the lens system 10' relative to the eye. Flange 30' may be designed to accommodate lens types presently used in vitreoretinal surgery, thus providing a means by which such existing lenses may be used advantageously without the need for a handle or suture down ring.