Patent Publication Number: US-2002010509-A1

Title: Scleral prosthesis for treatment of presbyopia and other eye disorders

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] This invention relates to methods of treating presbyopia, hyperopia, primary open angle glaucoma and ocular hypertension and more particularly to methods of treating these diseases by increasing the effective working distance of the ciliary muscle. The invention also relates to increasing the amplitude of accommodation of the eye by increasing the effective working range of the ciliary muscle.  
       [0003] 2. Brief Description of the Prior Art  
       [0004] In order for the human eye to have clear vision of objects at different distances, the effective focal length of the eye must be adjusted to keep the image of the object focused as sharply as possible on the retina. This change in effective focal length is known as accommodation and is accomplished in the eye by varying the shape of the crystalline lens. Generally, in the unaccommodated emmetropic eye the curvature of the lens is such that distant objects are sharply imaged on the retina. In the unaccommodated eye near objects are not focused sharply on the retina because their images lie behind the retinal surface. In order to visualize a near object clearly, the curvature of the crystalline lens is increased, thereby increasing its refractive power and causing the image of the near object to fall on the retina.  
       [0005] The change in shape of the crystalline lens is accomplished by the action of certain muscles and structures within the eyeball or globe of the eye. The lens is located in the forward part of the eye, immediately behind the pupil. It has the shape of a classical biconvex optical lens, i.e., it has a generally circular cross section having two convex refracting surfaces, and is located generally on the optical axis of the eye, i.e., a straight line drawn from the center of the cornea to the macula in the retina at the posterior portion of the globe. In the unaccommodated human eye the curvature of the posterior surface of the lens, i.e., the surface adjacent to the vitreous body, is somewhat greater than that of the anterior surface. The lens is closely surrounded by a membranous capsule that serves as an intermediate structure in the support and actuation of the lens. The lens and its capsule are suspended on the optical axis behind the pupil by a circular assembly of very many radially directed elastic fibers, the zonules, which are attached at their inner ends to the lens capsule and at their outer ends to the ciliary muscle, a muscular ring of tissue, located just within the outer supporting structure of the eye, the sclera. The ciliary muscle is relaxed in the unaccommodated eye and therefore assumes its largest diameter. According to the classical theory of accommodation, originating with Helmholtz, the relatively large diameter of the ciliary muscle in this condition causes a tension on the zonules which in turn pulls radially outward on the lens capsule, causing the equatorial diameter of the lens to increase slightly and decreasing the anterior-posterior dimension of the lens at the optical axis. Thus, the tension on the lens capsule causes the lens to assume a flattened state wherein the curvature of the anterior surface, and to some extent the posterior surface, is less than it would be in the absence of the tension. In this state the refractive power of the lens is relatively low and the eye is focused for clear vision for distant objects.  
       [0006] When the eye is intended to be focused on a near object, the ciliary muscles contract. According to the classical theory, this contraction causes the ciliary muscle to move forward and inward, thereby relaxing the outward pull of the zonules on the equator of the lens capsule. This reduced zonular tension allows the elastic capsule of the lens to contract causing an increase in the antero-posterior diameter of the lens (i.e., the lens becomes more spherical) resulting in an increase in the optical power of the lens. Because of topographical differences in the thickness of the lens capsule, the central anterior radius of curvature decreases more than the central posterior radius of curvature. This is the accommodated condition of the eye wherein the image of near objects falls sharply on the retina.  
       [0007] Presbyopia is the universal decrease in the amplitude of accommodation that is typically observed in individuals over  40  years of age. In the person having normal vision, i.e., having emmetropic eyes, the ability to focus on near objects is gradually lost, and the individual comes to need glasses for tasks requiring near vision, such as reading.  
       [0008] According to the conventional view the amplitude of accommodation of the aging eye is decreased because of the loss of elasticity of the lens capsule and/or sclerosis of the lens with age. Consequently, even though the radial tension on the zonules is relaxed by contraction of the ciliary muscles, the lens does not assume a greater curvature. According to the conventional view, it is not possible by any treatment to restore the accommodative power to the presbyopic eye. The loss of elasticity of the lens and capsule is seen as irreversible, and the only solution to the problems presented by presbyopia is to use corrective lenses for close work, or bifocal lenses, if corrective lenses are also required for distant vision.  
       [0009] Certain rings and/or segments have been used in ocular surgery for various purposes. Rings and/or segments of flexible and/or elastic material, attached or prepared in situ by fastening the ends of strips of the material around the posterior portion of the globe, posterior to the pars plana (over the underlying retina), have been used to compress the sclera in certain posterior regions. Supporting rings of metal, adapted to fit the contour of the sclera have been used as temporary supporting structures during surgery on the globe. However, none of these known devices have been used for surgical treatment of presbyopia, and none have been adapted to the special needs of prosthetic devices used in treating presbyopia.  
       [0010] Accordingly, a need has continued to exist for a method of treating presbyopia that will increase the amplitude of accommodation of the presbyopic eye, thereby lessening or eliminating the need for auxiliary spectacle lenses to relieve the problems of presbyopia.  
       SUMMARY OF THE INVENTION  
       [0011] The treatment of presbyopia has now been facilitated by the prosthetic device of this invention which is implanted within a pocket formed in the sclera of the globe of the eye in the vicinity of the plane of the equator of the crystalline lens. The prosthetic device of the invention comprises a base, having an elongated planform, and a ridge extending along at least a major portion of the elongated planform. The prosthesis is inserted into the scleral pocket with the base oriented in a generally outward direction from the center of the globe, and the ridge directed inwardly. The anterior edge of the prosthesis accordingly applies an outward force on the anterior edge of the scleral pocket which elevates the portion of the sclera attached thereto and the ciliary body immediately beneath the sclera to increase the working distance of the ciliary muscle according to the theory of the inventor.  
       [0012] Accordingly, it is an object of the invention to provide a treatment for presbyopia.  
       [0013] A further object is to provide a treatment for presbyopia by increasing the effective working distance of the ciliary muscle in the presbyopic eye.  
       [0014] A further object is to provide a treatment for presbyopia by increasing the radial distance between the equator of the crystalline lens and the ciliary body.  
       [0015] A further object is to provide a treatment for presbyopia by implanting in the sclera a plurality of prostheses which will increase the working distance of the ciliary muscle.  
       [0016] A further object is to provide a treatment for hyperopia.  
       [0017] A further object is to provide a treatment for primary open angle glaucoma.  
       [0018] A further object is to provide a treatment for ocular hypertension.  
       [0019] A further object is to provide a treatment for increasing the amplitude of accommodation of the eye.  
       [0020] Further objects of the invention will become apparent from the description of the invention which follows. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0021]FIG. 1 shows an isometric view of an eye having the prosthesis of this invention implanted therein.  
     [0022]FIG. 2 shows a front elevational view of an eye showing the location of straight scleral pockets.  
     [0023]FIG. 3 shows a front elevational view of an eye showing the location of straight scleral pockets.  
     [0024]FIG. 4 shows a cross section of the eye of FIG. 2 along the line  4 - 4 .  
     [0025]FIG. 5 shows an enlarged view of the cross section of FIG. 4 in the region indicated by the circle  5 .  
     [0026]FIG. 6 shows a plan view of a rectangular embodiment of the prosthesis of the invention having a flat base.  
     [0027]FIG. 7 shows a front elevational view of the prosthesis illustrated in FIG. 6.  
     [0028]FIG. 8 shows an end elevational view of the prosthesis shown in FIG. 6.  
     [0029]FIG. 9 shows a plan view of an embodiment of the prosthesis that is curved in the plane of the base.  
     [0030]FIG. 10 shows an end view of the prosthesis of FIG. 9 as indicated by the line  10 - 10 .  
     [0031]FIG. 11 illustrates a plan view of an alternate embodiment of the prosthesis of the invention.  
     [0032]FIG. 12 shows a front elevational view of the prosthesis illustrated in FIG. 11.  
     [0033]FIG. 13 shows an end elevational view of the prosthesis of FIG. 11.  
     [0034]FIG. 14 illustrates a plan view of an embodiment of the invention in which the ridge member extends beyond the end of the base member.  
     [0035]FIG. 15 shows a front elevational view of the prosthesis illustrated in FIG. 14.  
     [0036]FIG. 16 a  shows an end elevational view of the prosthesis of FIG. 14, wherein the base prosthesis is tapered to the posterior edge.  
     [0037]FIG. 16 b  shows an end elevational view of a prosthesis similar to that shown in FIGS. 14, 15 and  16   a , wherein the base is not tapered.  
     [0038]FIG. 17 shows a plan view of an embodiment of the prosthesis of the invention wherein the prosthesis is hollow and made of an elastomeric material that is filled with a liquid.  
     [0039]FIG. 18 shows a front elevational view of the prosthesis illustrated in FIG. 17.  
     [0040]FIG. 19 shows a cross sectional view of the prosthesis of FIG. 17 along the line  19 - 19 .  
     [0041]FIG. 20 shows an end elevational view of the prosthesis of FIG. 17.  
     [0042]FIG. 21 illustrates a plan view of an embodiment of the prosthesis of the invention wherein the base is curved to match the curvature of the globe.  
     [0043]FIG. 22 shows a front elevational view of the prosthesis illustrated in FIG. 21.  
     [0044]FIG. 23 shows an end elevational view of the prosthesis of FIG. 21. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS  
     [0045] This invention is based on a different theory, developed by the inventor, which has been described in U.S. Pat. No. 5,354,331, the entire disclosure of which is incorporated herein by reference, regarding the cause of the loss of amplitude of accommodation that constitutes presbyopia. According to the invention, presbyopia is treated by increasing the effective working distance of the ciliary muscle. This is accomplished by increasing the distance between the ciliary muscle and the lens equator by increasing the diameter of the sclera in the region of the ciliary body.  
     [0046] According to the invention the effective working distance of the ciliary muscle is increased by implanting in pockets surgically formed in the sclera of the eye a plurality of prostheses designed to place an outward traction on the sclera in the region of the ciliary body. The relevant anatomy of the eye for locating the scleral pockets may be seen by reference to FIGS.  1 - 4 . The outermost layer of the eye  100  comprises the white, tough sclera  102  which encompasses most of the globe and the transparent cornea  104 , which constitutes the anterior segment of the outer coat. The circular junction of the cornea and sclera is the limbus  106 . Within the globe of the eye, as illustrated in the cross-section of FIG. 4, the crystalline lens  108  is enclosed in a thin membranous capsule and is located immediately posterior to the iris  112 , suspended centrally posterior to the pupil  114  on the optical axis of the eye. The lens  108  is suspended by zonules  115  extending between the lens capsule at the equator  110  of the lens  108  and the ciliary body  116 . The ciliary body  116  lies just under the sclera  102  (i.e., just inwardly of the sclera  102 ) and is attached to the inner surface of the sclera  102 . As may be seen in FIG. 4, the ciliary body  116  lies generally in a plane  130  defined by the equator  110  of the lens  108 . The plane  130  can also be extended to intersect the sclera  102  whereby it forms a generally circular intersection located about 2 millimeters posterior to the limbus  106 . The external muscles  118  of the eyeball control the movement of the eye.  
     [0047] According to the invention a generally outwardly directed traction is exerted on the sclera in the region of the ciliary body to expand the sclera  102  in that region. This expansion of the sclera  102  produces a corresponding expansion of the attached ciliary body  116  and moves-the ciliary body  116  outwardly away from the equator of the lens  108 , generally in the plane  130  of the equator  110  of the lens  108 . The sclera  102  is preferably expanded approximately in the plane of the equator of the lens  108 . However, any expansion of the sclera  102  in the region of the ciliary body  116 , i.e., in the region of the sclera somewhat anterior or posterior to the plane of the equator  110  of the lens  108  is within the scope of the invention, provided that such expansion of the sclera  102  moves the ciliary body  116  away from the equator  110  of the lens  108 . Typically, the expansion of the sclera will be accomplished in the region from about 1.5 millimeters anterior to the plane  130  of the equator of the lens  108  to about 2.5 millimeters posterior to that plane, i.e., from about 0.5 millimeters to about 4.5 millimeters posterior to the limbus  106 . Accordingly, the anterior margin  122  of a scleral pocket  120  will be located in that region of the sclera.  
     [0048] The prosthesis of the invention is designed to apply an outwardly directed traction to the sclera at the general position of the anterior margin  122  of a scleral pocket  120 . Accordingly, the prosthesis of the invention has a base adapted to be placed against the outer wall of the pocket surgically formed in the sclera. The base has an elongated planform and is oriented generally circumferentially with respect to the circle defined on the sclera by the intersection therewith of the plane  130  of the equator  110  of the lens  108 .  
     [0049] The position of the prosthesis within a scleral pocket and its operation to expand the sclera are illustrated in FIGS. 4 and 5, showing a prosthesis of the type illustrated in FIGS.  6 - 8 .  
     [0050] The base member  202  of the prosthesis  200  has a smooth exterior face  212  adapted to be placed in contact with the internal surface of the outer wall  128  of the scleral pocket  120 . The opposite, or interior, face  214  of the prosthesis  200  is provided with a ridge  210  extending along a substantial portion of the length of the base  202 . This ridge bears against the inner wall  126  of the scleral pocket  120 . Accordingly, the sclera  102  at the anterior margin  122  of the scleral pocket  120  is elevated above its original level. The attached ciliary body  116  is thereby also expanded away from the equator  110  of the lens  108 , and the working distance of the ciliary muscle is increased.  
     [0051] A first embodiment of the prosthesis of the invention is illustrated in FIGS.  6 - 8 . FIG. 6 shows a plan view of the inner face of the prosthesis  200  having a base  202  with an anterior edge  204 , a posterior edge  206 , and lateral ends  208  and  210 . The inner face  212  is provided with a ridge  214  extending along the length of the major dimension of the elongated base  202 . FIG. 7 shows a front elevational view of the prosthesis of FIG. 6 showing the flat, smooth outer surface  216  of the prosthesis. FIG. 8 shows a side view of the prosthesis showing the outer surface  216 , the ridge  214  and a notch  218  on the inner surface  212  of the prosthesis.  
     [0052] FIGS.  9 - 10  illustrate a prosthesis of the invention having a curved planform adapted to be implanted in a scleral pocket that is curved to match the curvature of the eyeball. The prosthesis  300  of FIGS.  9 - 10  has a generally planar base  302 , curved in the plane of the base  302 , having an anterior edge  304 , a posterior edge  306 , and lateral ends  308  and  310 . The inner face  312  is provided with a ridge  314  extending along the length of the major dimension of the elongated curved base  302 . FIG. 11 shows an end view of the prosthesis of FIG. 9 showing the outer face  316 , the ridge  314  and a notch  318  on the inner face  312  of the prosthesis. The curvature of the base is chosen to provide at least an approximate match for the curvature of the adjacent structures on the surface of the sclera, e.g., the limbus  106 , adjusted for the distance of the scleral pocket  120  and prosthesis  300  from the limbus  106 . FIG. 3 shows a front elevational view of an eye provide with curved scleral pockets  120  to accommodate a curved prosthesis  300  of the type illustrated in FIGS. 9 and 10.  
     [0053] FIGS.  11 - 13  show an embodiment of the invention wherein the anterior portion is tapered from the ridge to the anterior edge. FIG. 11 shows a plan view of the prosthesis  400  having a base  402  with an anterior edge  404 , a posterior edge  406 , and lateral ends  408  and  410 . The outer face  416  is smooth and adapted to be placed against the inner surface of the outer wall  128  of a scleral pocket  120 . The inner face  412  is provided with a ridge  414  extending along the length of the major dimension of the elongated base  402 . FIG. 12 shows a front elevational view of the prosthesis of FIG. 11 showing the flat, smooth outer face  412  of the prosthesis. FIG. 13 shows an end view of the prosthesis of FIG. 11 showing the outer face  412  and the ridge  410  on the inner face  414  of the prosthesis  400 . In this embodiment the ridge  410  tapers toward the anterior edge  404  of the prosthesis.  
     [0054] FIGS.  14 - 16  show a preferred embodiment of the prosthesis in which the ridge member includes extensions beyond the ends of the base member which lie on the surface of the sclera adjacent to the scleral pocket and help to stabilize the prosthesis. FIG. 14 shows a plan view of this embodiment  500  having a base  502  with an anterior edge  504 , a posterior edge  506 , and lateral ends  508  and  510 . The inner face  512  is provided with a ridge  514 . The ends  508  and  510  of the base  502  extend slightly beyond the ends of the ridge  514 . Accordingly, the ends.  508  and  510  of the base  502  will extend beyond the ends of the pocket  120  and lie on the surface of the sclera  102 . FIG. 15 shows a front elevational view of the prosthesis of FIG. 14 showing the flat, smooth outer face  516  of the prosthesis and the ends  508  and  510  of the base  502  extending beyond the ends of the ridge  514 . FIG. 16 a  shows an end view of the prosthesis of FIG. 14 showing the smooth outer face  512  and the ridge  510  on the inner face  514  of the base  502 , as well as a notch  518 . FIG. 16 b  shows and end view of an alternate embodiment of the prosthesis  500  wherein the base  502  does not taper all the way to the posterior edge  506 . Evidently, the thickness of the posterior edge  506  may vary from a relatively sharp posterior edge as shown in FIG. 16 a  to a relatively thick posterior edge as shown in FIG. 16 b , or even thicker if it is advantageous.  
     [0055] FIGS.  17 - 20  illustrate an embodiment of the prosthesis that is hollow and made from a plastic or elastomeric material and filled with a liquid. FIG. 17 shows a plan view of this embodiment  600  having a base  602  with an anterior edge  604 , a posterior edge  606 , and lateral ends  608  and  610 . The inner face  612  is smoothly rounded and rises to a crest  614  that serves to support the prosthesis on the inner wall  126  of the scleral pocket  120  in the same way as the ridge member of other embodiments of the invention. FIG. 18 shows a front elevational view of the prosthesis of FIG. 17 showing the flat, smooth outer face  614  of the prosthesis. FIG. 19 shows a cross section of the prosthesis of FIG. 17 taken along the line  19 - 19 . The cross-section shows the flexible wall  612  of the prosthesis as well as the flat outer face  616 , and the crest  614 . The cross section also shows the filling liquid  620 . FIG. 20 shows an end view of the prosthesis of FIG. 17 showing the outer face  616  and the crest or ridge  614  on the inner face  612  of the prosthesis  600 . The hollow prosthesis is filled with liquid, typically by injecting the liquid through an end  608  or  610 . The prosthesis may be filled with more or less liquid in order to adjust the thickness between the outer face  616  and the crest or ridge  614  to provide more or less traction on the sclera at the anterior margin  122  of the scleral pocket or belt loop  120 .  
     [0056] FIGS.  21 - 23  illustrate an embodiment of the invention generally similar to that shown in FIGS.  6 - 8 , having, however, a base in which the inner face of the prosthesis is curved to provide an approximate match to the curvature of the globe. FIG. 21 shows a plan view of the inner face of the prosthesis  700  having a base  702  with an anterior edge  704 , a posterior edge  706 , and lateral ends  708  and  710 . The inner face  712  is provided with a ridge  714  extending along the length of the major dimension of the elongated base  202 . FIG. 22 shows a front elevational view of the prosthesis of FIG. 21 showing the curved, smooth outer surface  716  of the prosthesis. FIG. 23 shows an end view of the prosthesis showing the outer surface  716 , the ridge  714  and a notch  718  on the curved inner surface  712  of the prosthesis.  
     [0057] A preferred embodiment of the scleral prosthesis is that shown in FIGS. 9 and 10, wherein the anterior rim  304  and the posterior rim  306  are both generally circular arcs. The taper in the diameter of the segment is preferably selected in an individual case to fit the globe in the region of the ciliary body. Accordingly, different sizes of segments will be provided wherein the radius of curvature of the anterior rim ranges from about 7.0 to about 10 millimeters in 0.50 millimeter increments. Accordingly, a preferred segment has a typical internal circular radius of curvature at its anterior portion of about 7.76 millimeters, at the position of the ridge of about 8.21 millimeters, and at the posterior rim of about 8.91 millimeters. The preferred segment has outer radius of curvature at its anterior portion of 8.02 millimeters, at its mid portion 8.47 millimeters, and at its base 8.94 millimeters. These measurements will vary depending on the size of the eye, the amount of rigidity required, and the strength of the material from which the segment is made. The preferred anterior chord length of the segment is 5 millimeters. The axial width of the segment will typically be about 2 millimeters.  
     [0058] The scleral prosthesis of the invention is made of a material that is sufficiently rigid to exert a force on the sclera sufficient to produce the radial expansion required by the method of the invention and that is physiologically acceptable for long-term implantation or contact with the ocular tissues. Such materials are well-known in the surgical art and include suitable metals, ceramics, and synthetic resins. Suitable metals include titanium, gold, platinum, stainless steel, tantalum and various surgically acceptable alloys, and the like. Suitable ceramics may include crystalline and vitreous materials such as porcelain, alumina, silica, silicon carbide, high-strength glasses and the like. Suitable synthetic materials include physiologically inert materials such as poly(methyl methacrylate), polyethylene, polypropylene, poly(tetrafluoroethylene), polycarbonate, silicone resins and the like. The prosthesis may also be made of composite materials incorporating a synthetic resin or other matrix reinforced with fibers of high strength material such as glass fibers, boron fibers or the like. Thus, the segment may be made of glass-fiber-reinforced epoxy resin, carbon fiber-reinforced epoxy resin, carbon fiber-reinforced carbon (carbon-carbon), or the like. The segment may be made of a semi-rigid exterior and a liquid or gel filled interior so that the internal and external dimensions can be altered by injecting various amounts of liquid: water, saline, or silicone oil; or various amounts of a gel: silicone, collagen, or gelatin. The semi-rigid exterior may be made of any of the already listed materials. A preferred material for the entire segment is surgical grade poly(methyl methacrylate).  
     [0059] The scleral prosthesis of the invention may be manufactured by any conventional technique appropriate to the material used, such as machining, injection molding, heat molding, compression molding and the like.  
     [0060] The scleral prosthesis may be foldable to facilitate insertion into a scleral belt loop or made in a plurality of parts so that it can be assembled prior to use or may be installed separately to form a complete prosthesis.  
     [0061] In practicing the method of the invention, the surgeon locates the proper region of the sclera to be expanded by measuring a distance of preferably 2.0 millimeters posterior of the limbus. At 2.5 millimeters clockwise and counterclockwise from each of the 45° meridians of the eye, and 2 millimeters posterior to the limbus, partial scleral thickness radial incisions, i.e., antero-posterior incisions, are made which are 2 millimeters long and 350 microns deep. Using a lamella blade the sclera is dissected until the partial thickness incisions are connected so that four scleral pockets or belt loops are made which have an anterior length of 5 millimeters, and a length extending generally axially of the eye of 2 millimeters. Thus, each pocket or belt loop is preferably centered over the 45° meridian of the eye. A prosthesis is then inserted in each of the four scleral belt loops. This produces symmetrical scleral expansion which will produce the desired result of increasing the effective working distance of the ciliary muscle.  
     [0062] The location of the prostheses of the invention when implanted in the eye is illustrated in FIGS.  1 - 4 . FIG. 1 is an isometric view of an eye  100  having a globe  102  with the relevant exterior anatomical parts indicated as discussed above.  
     [0063]FIGS. 2 and 3 show front elevational views of an eye  100  showing the scleral pockets  120  formed at approximately the 45° meridians of the eye, i.e., approximately halfway between the vertical and horizontal meridians of the globe. This location is preferred because it avoids interference with structures of the eye that are located generally on the vertical and horizontal meridians. FIG. 2 shows the use of curved scleral pockets  120  to permit the use of curved prostheses of the type illustrated in FIGS. 9 and 10. FIG. 3 shows the use of straight scleral pockets  120 . Such straight pockets are somewhat simpler to prepare surgically. For many patients the use of straight prostheses can provide adequate treatment of their presbyopia.  
     [0064]FIG. 4 shows a cross-section of the eye, taken along the line  4 - 4  in FIG. 3, showing the placement of the prosthesis of the invention relative to the significant anatomical structures of the eye. This figure shows the general configuration of the scleral pockets  120  and the prostheses  200  of the type illustrated in FIGS.  6 - 8  in a preferred embodiment. The anterior margins  122  of the scleral pockets or belt loops  120  are located approximately in the plane  130  of the equator  110  of the lens  108 . The ridge  210  of the prosthesis causes the anterior portion of the pocket to be expanded somewhat more than the posterior portion. This places the sclera at the anterior margin of the pocket under a radial tension and causes it to expand somewhat from its normal diameter at that position. This scleral expansion draws with it the underlying ciliary body  116  and causes the ciliary body to be drawn away from the equator  110  of the lens  108 . Accordingly, the expansion of the ciliary body  116  operates to increase the working distance of the ciliary muscle and restore, at least in part, the ability of the eye to accommodate for clear focusing on objects at different distances. FIG. 5 shows an enlarged portion of one of the scleral pockets  120  with adjacent anatomical structures. It shows the relation of the scleral pocket  120  to the underlying structures and its location just posterior to the equator of the lens  108  and overlying the ciliary body  116 .  
     [0065] The method of the invention which increases the amplitude of accommodation may also be of benefit in treatment of hyperopia in certain patients. Some youthful hyperopes can achieve relatively normal vision by compensating for their hyperopia through the natural accommodative ability of the eye. However, as this ability declines with age, they find that it becomes more difficult to attain normal vision by this process, and they begin to experience headaches and other symptoms, even at an age somewhat less than usual for the onset of presbyopia. Evidently, increasing the amplitude of accommodation by the method of this invention would be useful in restoring the ability of these patients to compensate for their hyperopia.  
     [0066] The method of this invention also has utility in the treatment of primary open-angle glaucoma, which shows a correlation with age in certain individuals. It has been found that, in general, intraocular pressure (IOP) exhibits a linear increase with increasing age. (Armaly, M. F., On the distribution of applanation pressure I. Statistical features and the effect of age, sex, and family history of glaucoma, Archives of Ophthalmology, Vol. 73, pp. 11-18 (1965)). Among the general population is found a group of individuals who develop abnormally high intraocular pressures as a result of primary open angle glaucoma, a disease which is one of the most prevalent causes of blindness in the world. According to the theory of this invention, the linear increase in IOP with age is a direct result of the decrease in distance between the lens equator and the ciliary muscle and the resulting linear decrease in the effective pull of the ciliary muscle. Since the ciliary muscle inserts into the trabecular meshwork, the decrease in pull will decrease the size of the trabeculum and/or the drainage pores and result in a linear increase of intraocular pressure with age. In this view, the patients who develop primary open angle glaucoma may have a congenital predilection to narrower pores, protein deposition in the pores, and/or a smaller trabecular meshwork, so that when the ability of the ciliary muscle to exert force declines, after the age of 40 or thereabouts, they tend to develop excessively elevated IOP.  
     [0067] The method of the invention which increases the effective working distance of the ciliary muscle, and thereby increases the force that it can exert when it contracts, restores the level of force which the ciliary muscle exerts on the trabecular meshwork to a value characteristic of a more youthful eye. In this way it is expected that the tendency of an eye that is disposed to develop primary open angle glaucoma as it ages would be overcome and the onset of this disease would be prevented or at least postponed.  
     [0068] The invention having now been fully described, it should be understood that it may be embodied in other specific forms or variations without departing from its spirit or essential characteristics. Accordingly, the embodiments described above are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.