WO2006/007475 PCT/US2005/022274 -1 OPHTHALMIC CLIP AND ASSOCIATED SURGICAL METHOD BACKGROUND OF THE INVENTION  The present invention is directed to an ophthalmic clip for treating vision disorders, such as presbyopia and/or glaucoma and an associated surgical method for application of the clip.  Presbyopia is a vision disorder associated with aging resulting from the failure of the accommodation mechanism of the eye. The accommodative mechanism is driven principally by parasympathetic inervation of the ciliary smooth muscle. In the non-presbyopic eye, this causes the muscle to slide forward in a unified manner and produces an inward movement of the muscle. The result is a reduction in the diameter of the ciliary muscle collar that instigates a series of events leading to an ability to see near objects clearly.  Presbyopia is most frequently treated by the use of reading glasses, bifocals, and progressive multi-focal contact lenses. However, the inconveniences associated with eyeglasses and contact lenses have prompted investigation into, and the development of, surgical techniques aimed at correcting presbyopia.  Glaucoma, specifically primary open angle glaucoma, is an eye disease that progressively damages the optic nerve, thus producing certain characteristic defects in the afflicted individual's peripheral vision. Primary open angle glaucoma occurs when the eye's drainage canals become clogged over time, causing a gradual and irreversible loss of vision. It is most commonly treated with eye drops, such as PILOCARPINE, PROPINE, TIMOLOL and XALATAN, which may have side effects. Oral medications are also used.  A method for treating presbyopia and glaucoma and a scleral clip for use in the method are disclosed in my U.S. Patent No. 6,517,555 and U.S. Published Application No. US 2004/0092968, both of which are incorporated herein by reference. The method involves applying a plurality of clips to the sclera underneath the conjunctiva. In the treatment of WO 2006/007475 PCT/US2005/022274 -2 presbyopia, the clips serve to support or reinforce the ciliary muscles so that they may work to alter the lens diameter for focusing on close objects. In the treatment of glaucoma, the tensioning of the sclera with the clips stretches the tissues of the eye that provide for drainage, thus reducing blockage of the drainage canals and facilitating drainage of fluid from the eye.  While the clips disclosed in my above-referenced patent and application are designed for use in the methods described therein, the development process has indicated a need for improved clips that (a) are easier to apply, (b) more securely grip the sclera, and (c) have a lower profile, thus making them more comfortable to the wearer.  Thus, it the object of the invention to provide an improved clip uniquely suited for use in the treatment of presbyopia and/or glaucoma and a method for applying the clip to the eye. SUMMARY OF THE INVENTION  These objects, as well as others which will become apparent upon reference to the following detailed description and accompanying drawings, are accomplished by a clip for attachment to the sclera that includes a pair of opposed teeth or feet that are adapted to be received in shallow, complementarily-shaped pockets made in the sclera, thus securing the clip thereto. The clip comprises a body portion having a working length of from approximately 3.5 to 6.0 mm, a width of from approximately 1.0 to 2.5 mm, and a thickness of from 600 pm to 2.00 mm. Depending from the opposite ends of the body are feet for securing the clip to the sclera and which have a working length of approximately 200 pm. The middle portion of the body of the clip is either curved downwardly (i.e., toward a plane defined by the opposed feet) or enlarged (in thickness) with respect to the ends so that the clip, when secured to the sclera, pushes downwardly thereon to compress the sclera. In a second embodiment, the working length of the feet is between approximately 1.5 mm and 2.5 mm. In a third embodiment, an additional foot extends from each end of the body so as to WO 2006/007475 PCT/US2005/022274 -3 overlie the feet referred to above and define a space therebetween for capturing the portion of the sclera defined by the incision for receiving the first-mentioned feet and the surface of the sclera. Three additional embodiments also include features that help maintain the clip in place after it is applied to the sclera.  The clip is formed of a resilient, biocompatible material. Preferably, the clip is made entirely of PMMA. Alternatively, the body of the clip may be made from PMMA, while the feet are made from titanium.  In a further aspect of the invention, a method for applying the clip is also provided. Pursuant to the method, the location of the ciliary muscles in the eye are determined, and an incision is made in the conjunctiva to gain access to the sclera overlying the ciliary muscles. The incision is opened to expose the sclera and opposed pockets are made in the surface of the sclera for receiving the feet of a clip, as described above. The clip is attached to the eye by introducing the feet of the clip into the pockets made in the sclera, with the downward curve of the body of the clip compressing the surface of the sclera inwardly. The conjunctiva is then closed over the clip. Optionally, a fibrin adhesive may be applied to the conjunctiva after it is closed over the clip in order to expedite the healing process. BRIEF DESCRIPTION OF THE DRAWINGS  Fig. 1 is a horizontal sectional view of an eyeball.  Fig. 2 is an anterior view of the eye showing the extrinsic eye muscles.  Fig. 3 is a perspective view of an improved clip in accordance with the present invention.  Fig. 4 is a front elevation of the clip of Fig. 3. [00015) Fig. 5 is an end view of the clip of Fig. 3.  Fig. 6 is a top view of the clip of Fig. 3.  Figs. 7-9 are similar views to Figs. 3, 4 and 6, and illustrate a second embodiment of an ophthalmic clip according to the present invention. [00018) Figs. 10-12 are similar to Figs. 3, 4 and 6, and WO2006/007475 PCT/US2005/022274 -4 illustrate a third embodiment of an ophthalmic clip according to the present invention. [00019} Figs. 13-15 are perspective views of three additional clip embodiments according to the present invention. DETAILED DESCRIPTION  The method that utilizes the clip of the present invention is based upon the theory that the cause of presbyopia is the failure of the ciliary body to adjust the lens diameter in order to focus images onto the retina for close objects. The ciliary muscles change the lens diameter by using the sclera as a support or fixation structure. As the sclera of the eye weakens due to age, the ciliary muscles lack the support needed to alter the lens diameter for focusing on close objects. Thus, to allow the ciliary muscle to alter the lens diameter to see close objects, the sclera must be supported or reinforced. Accordingly, an improved clip for reinforcing the sclera is provided, so as to form a stronger and more stable support for the ciliary muscles. The clip of the present invention accomplishes this by compressing or depressing the selera. In effect, the sclera is strengthened, and the ciliary muscles are then able to again function properly to provide near vision.  It is believed that the method and its associated clip may also be advantageously used for the treatment of open angle glaucoma. Glaucoma, like presbyopia, is an age-related disease and is caused by a buildup of fluid pressure in the eye which damages the optic nerve. Over time, glaucoma destroys peripheral vision, thus shrinking the field of vision. In a healthy eye, the fluid produced by the ciliary tissues surrounding the lens drains out of the eye through a series of drainage canals around the outer edge of the iris. With age, because the ciliary muscles lack support, they are less capable of maintaining these drainage canals in an open condition to allow free drainage of fluid. By supporting the sclera with the clip disclosed herein, and according to the present method, support is provided for the ciliary muscles, and the tissues of the eye that provide for drainage are stretched, thus reducing blockage of the fluid drainage canals and facilitating the WO 2006/007475 PCT/US2005/022274 -5 drainage of fluid from the eye.  With reference to Fig. 1, there is seen a simplified sectional view of a human eye 10 having a lens 12 contained within a lens capsule 14. The ciliary body and ciliary muscle 16 are connected to the lens capsule 14 and also to the choroid 18. The sclera 20 overlies the choroid 18 and, at the front of the eye, the ciliary muscles 16, and terminates in the sclera spur 22 at the cornea 24 of the eye. The conjunctiva 26 surrounds the cornea 24 and overlies the bulbar sheath (or Tenon's capsule) 28 which, in turn, overlies the sclera 20 on the front of the eye 10. Blood is supplied to the sclera by arteries in the superior, inferior, medial and lateral rectus muscles 30, 32, 34, and 36 respectively, best seen in Fig. 2.  An improved clip, generally designated 40, for application to the sclera is shown in Figs. 3-6. The clip, generally designated 40 includes a body portion 42, with two opposed feet 44 extending from the opposite ends of the body. As can be appreciated, the clip 40 should present no sharp edges that would irritate or damage tissue that comes into contact therewith.  In practice, the body 42 has a length that may vary from approximately 3.5 mm to 6.0 mm, depending on the desired degree of compression of the sclera. Where less compression is indicated, most likely in younger patients, a shorter clip is used. Conversely, where more compression is indicated, most likely in older patients, a longer clip is used. As can be appreciated, the length of the body 42 also generally defines the working length of the clip. The body 42 has a width of from approximately 1.0 mm to 2.5 mm, and a thickness of from between approximately 600 Vm to 2.00 mm.  The opposed feet 44 are generally L-shaped (as seen in Fig. 4), with the free end of the long leg 46 of the L having a curved or semi-circular configuration (best seen in Figs. 3 and 6) so as to reduce the likelihood of damage to tissue contacted by the feet. These curved ends are adapted to be received in pockets made in the surface of the sclera, as will be discussed in greater detail below.
WO 2006/007475 PCT/US2005/022274 -6  The feet 44 have a working length, as defined by the long leg 46 of the L, of approximately 200 pm. The short leg 48 of the L measures between approximately 100 pm in length and 200 tm in length. Thus, the overall length of the clip 40 is the sum of the length of the two feet 44 and the length of the body 42, and consequently ranges from approximately 4.0 mm to 6.5 mm.  In keeping with an aspect of the invention, the body 42 of the clip 40 is formed with a reverse bend (i.e., the body curves downwardly) so that, when the clip 40 is applied to the eye, the clip 40 pushes down on or compresses the sclera, thus causing additional deformation of the sclera. Alternatively, the central portion of the body 42 of the clip 40 may be greater in thickness than the ends to achieve the same effect. The amount of the reverse bend is generally the same as the length of the leg 48 of the feet 44, i.e., from 100 pm to 200 pm, but may be more or less depending upon the amount of scleral compression needed.  The reverse bend exerts an inward force to assist the failing contraction of an aging ciliary body, thus providing what is known as the "Baikoff wedge effect," named after George Baikoff, M.D. More specifically, the pressure created by the reverse bend pushes the ciliary muscle inward and forward, modifying the position of the ciliary processes and the location of the zonular plexus, and thus releasing the tension of the zonule and provoking the deformation of the crystalline lens by allowing the lens to move forward and increase its anterior curvature. This allows for an increase in the lenticular power, thus causing the lens to accommodate. Alternatively, the clip body could be enlarged in the central area between the points to provide the same effect.  The clip 40 may be made of a variety of suitable biocompatible materials, including titanium and polymethyl methacrylate (PMMA). Preferably, the entire clip is molded from PMMA. Alternatively, the body 42 of the clip 40 may be molded from PMMA, while the feet 44 are made from titanium. The titanium feet 44 are secured to the body 42 by overmolding the WO 2006/007475 PCT/US2005/022274 -7 body with the feet 44 in situ, so that the molten PMMA flows around securement legs 50 that extend from the short leg 48 of the feet 44. The securement legs 50 may be as much as 500 pm in length, to insure that a sufficient length is received in the body 42 to maintain structural integrity. The clip may also be coated with appropriate bioactive materials, such as sytostatic drugs which have anti-inflammatory characteristics.  Turning to Figs. 7-9, a further embodiment of an ophthalmic clip 40 according to the present invention is shown. The clip is similar, except dimensionally, to that shown in Figs. 3-6, and identical reference numerals are used. With reference to Figs. 7-9, the body 42 has a length that may vary from approximately 2.0 mm to 5.0 mm (preferably approximately 2.5 mm), depending on the desired degree of compression of the sclera. The clip 40 has a width of from approximately 1.0 mm to 2.5 mm (preferably approximately 1.0 mm), and a thickness of from between approximately 200 pm to 1.00 mm (preferably approximately 250 pm).  The opposed feet 44 are generally L-shaped (as seen in Fig. 8), with the free end of the long leg 46 of the L having a curved or semi-circular configuration (best seen in Figs. 7 and 9) so as to reduce the likelihood of damage to tissue contacted by the feet. These curved ends are adapted to be received in pockets made in the surface of the sclera, as will be discussed in greater detail below.  The feet 44 have a working length, as defined by the long leg 46 of the L, of approximately 1.5 mm to 2.5 mm (preferably approximately 2.5 mm), the longer length helping to maintain the clip in the pockets in the sclera. The short leg 48 of the L measures between approximately 800 Am in length and 1.5 mm in length and is preferably approximately 800 Am in length. The overall length of the clip 40 ranges from approximately 5.0 mm to 7.5 mm.  The body 42 of the clip 40 is formed with a reverse bend (i.e., the body curves downwardly) so that, when the clip 40 is applied to the eye, the clip 40 pushes down on or WO 2006/007475 PCT/US2005/022274 -8 compresses the sclera, thus causing additional deformation of the sclera. In practice the reverse bend has a radius of curvature of between 6.0 mm and about 9.0 mm and is preferably approximately 7.5 mm. [0,0034] Turning to Figs. 10-12, a third embodiment of a clip 54 according to the present invention is shown. The clip 54 is similar to that shown in Figs. 7-9, so that identical reference numerals are used for corresponding structure. As seen in Figs. 10-12, the clip 54 includes an additional foot 56 extending from each end of the body and overlying the foot 46 so as to define a space 58 therebetween. The space 58 is adapted to receive therein the portion of the sclera defined by the incision for making the pocket 52 for receiving the foot 46 and the surface of the sclera, and measures approximately 300-400 um. When applied to the sclera, the feet 46, 56 capture the sclera therebetween to help maintain the clip in position.  The clip may include other features that help ensure that the feet are retained in the pockets made in the sclera. With reference to Fig. 13, a fourth clip embodiment is shown, generally designated 60. The clip 60 comprises two parts 62,64. The first part 62 is similar to the clip 40 shown in Figs. 7-9. The second part 64 overlays the first part 62 and includes a series of retaining pegs (3 shown) 66a,b,c that are received in mating apertures 68a,b,c in the feet and body of the first part 62. When the feet of the first clip portion are received in the pockets made in the sclera, a "pin hole" is made in the pocket through which the retaining pegs 66a, 66c are placed in order to be inserted into the apertures 64a, 64c, thus positively securing the clip 60 to the sclera. The central peg 66b on the second part 64 and aperture 68b on the first part 62 help to properly locate and align the two parts of the clip 60 during their assembly and application to the eye.  A further alternative of the clip is shown in Fig. 14, and is generally designated 70. The clip 70 is generally similar to that shown in Figs. 7-9, but includes a central aperture 72 in the body portion of the clip through which is received a "screw" or other fastener 74. The screw 74 has a WO 2006/007475 PCT/US2005/022274 -9 point that, upon insertion into the central aperture 72, bites into the sclera to a depth of, e.g., approximately 100 Am to secure the clip 70 thereto. For example, the shank of the screw 74 may include, e.g., a spiral thread or hook to positively secure the clip to the sclera.  Turning to Fig. 15, an additional embodiment of the clip, generally designated 80 is shown that also has means for ensuring that the clip stays in place on the sclera. The clip 80 is similar to that shown in Figs. 7-9, except that each foot has at least one aperture 82 therein through which scleral tissue will grow after application of the clip 80 to the eye as part of the healing response to making the incision for the pockets that receive the feet of the clip. The tissue that grows through apertures 82 thus serves to hold the clip in place on the eye.  A method of applying the clip of the present invention to the eye will now be set forth. First, the eyelid is held open with a lid speculum and a topical anesthetic, such as a sub-conjunctival lidocaine, is applied to the eye. Then, the location of the ciliary body is determined, for example, by using commercially-available ultrasound equipment. With reference to Fig. 2, an incision 38 is then made in the conjunctiva parallel to the scleral-limbal junction so as to dissect the conjunctiva bypassing the Tenon's capsule 28. The incision is then deepened into the episclera. The incision is opened and, if necessary, the Tenon's capsule is laterally moved to expose the sclera 20. Opposed pockets 52 are made in the surface of the sclera for receiving the opposed feet of the clip using a preset marker. The openings of the pockets are spaced approximately 3.5 to 6.0 mm apart, depending on the length of the clip body, and have a depth (in a direction generally parallel to or concentric with the surface of the sclera) that corresponds to the length of the foot, i.e., from between approximately 200 im to 2.5 mm. The pockets extend no deeper into the sclera from the surface thereof than approximately 50 percent of its thickness, i.e., no deeper than about 350 pm, and WO 2006/007475 PCT/US2005/022274 -10 preferably extend no deeper than approximately 200 Vm.  The clip is then loaded onto an application tool, which may simply comprise a grasping forceps, which grips the short legs of the feet to apply an axially compressive force to the clip along its body, thus bending the body and moving the feet toward each other. The feet are then introduced into the pockets 52 made in the sclera. If the clip 54 according to Figs. 10-12 is used, the portion of the sclera between the incision for the pocket 52 and the surface of the sclera is received in the space 58 between in the feet 46 and 56. If the clip 60 according to Fig. 13 is used, additional pin holes are made in the pockets for receipt of the pegs 66a, 66c. Once these holes in the pocket are made, the second part of the clip 62 is assembled onto the first part of the clip 62. If the clip 70 according to Fig. 14 is used, the screw 74 is inserted into the aperture 72 and manipulated so that the point thereof bites into the sclera.  The applied clips have a generally low profile, closely adhering to the curvature of the eye, thus providing reinforcement to the sclera. The Tenon's capsule 28 is then reapposed over the clip and the conjunctiva closed. No suturing is needed as the conjunctiva self seals. Preferably, a fibrin adhesive, such as Tisseel® VH fibrin sealant available from Baxter Healthcare Corporation, may be applied over the closed conjunction to accelerate healing. The procedure is then repeated for each of the four quadrants, as deemed necessary by the surgeon, so that the clips are applied to the eye equally spaced about the cornea 24 between the adjacent rectus muscles. An ointment is applied to the eye, which is then patched for 24 hours.  As can be readily appreciated, the procedure can be simply reversed by merely again gaining access to the sclera by making an incision in the conjunctiva over the clip, moving the Tenon's capsule to expose the clip, and then removing the clip.  The application of each clip should deform the uvea and move the sclera inwardly approximately 0.5 mm, for a total of 2 mm if four clips are applied. This will increase the WO 2006/007475 PCT/US2005/022274 -11 amplitude of accommodation, thus reversing the effects of presbyopia. This inward movement of the sclera should also increase the angle of the canals of Schlemn, thus increasing the aqueous flow and decreasing the intra-ocular pressure, to ameliorate the effects of glaucoma.  Thus, a method and a clip for performing the method have been provided that fully meet the objects of the present invention. While the invention has been described in terms of a preferred ophthalmic clip and method, there is no intent to limit the invention to the same. Indeed, the clip may have application to medical procedures in addition to that described above. Instead, the invention is defined by the scope of the following claims.