Patent Publication Number: US-RE34424-E

Title: Intraocular lens

Description:
The present invention relates to intraocular lenses and, more particularly, to lenses having stable fixation members providing superior flexibility to minimize irritation of tissues and reduce postoperative complications. 
     The visual rehabilitation of a patient afflicted with cataract has been a controversial topic within the cognoscente for decades. To understand the concept of intraocular lens implants, one must first have an intimate knowledge of the anatomy of the eye and the characteristics of a cataract. Referring to a cross-sectional diagram of an eye, light enters through the cornea. The cornea is a clear transparent tissue that serves as a window which allows entry of light and provides some amount of focusing capability. The light transverses the anterior chamber and penetrates the crystaline lens. The lens acts as a major focusing element for the light. The light, after being focused by the lens, continues on its path through the vitreous and impinges upon the retina. The impinging light is transformed into electrical impulses by the reaction of layers of complex specialized retinal nerves. The nerves transmit the electrical impulses to the brain which translates them into visual sensations. 
     The word &#34;cataract&#34; refers to a clouding of the normally clear lens. The causes of cataract need not be reviewed except to say that senile cataract is an extremely common afflication of patients over the age of sixty and leads to varying amounts of significant visual disability. When a cataract is present, the light normally penetrating the crystaline lens for focusing is impaired by the clouded areas. When the cataract becomes severe enough, the only treatment available is surgical removal of the cataract which is equivalent to surgical removal of the crystaline lens. At the present time, there are no medicinal cures for most patients afflicted with cataract. 
     Innumerable techniques for cataract removal have been described and are currently in practice. The techniques for cataract removal fall into one of two broad categories: (1) intracapsular cataract surgery involves removal of the entire cataract or crystaline lens together with its supporting capsular tissue. Removal is usually accomplished surgically with the aid of cryosurgery and the resulting eye is left with the vitreous cavity in intimate contact with the posterior surface of the iris. (2) extracapsular cataract surgery involves the removal of the cataract or crystaline lens interior while leaving the capsular tissue either partially or entirely intact within the eye. The important distinction between these two categories is that in extracapsular surgery the capsular tissue or outer envelope of the lens is left in place to separate part or all of the vitreous from the more anterior structures of the eye. 
     With the surgical removal of the crystaline lens, the resulting eye is deficient in focusing power. In the early years of cataract surgery, this deficiency of focusing power was corrected by using a thick lens held in front of the eye by a spectacle frame. This thick lens did correct the focusing power in the central parts of a patient&#39;s field of view but was very poor in focusing upon objects that were offcenter and toward the periphery. As a result, the patients wearing these thick lenses had a type of tunnel vision; any objects that were not in the center vision were very much distorted or completely absent from view. Because the lenses were very thick, the spectacles were very difficult to fit properly, were constantly in need of adjustment and the cosmetic effect of the lens were very poor. 
     Improvements in visual rehabilitation came with the availability of contact lenses. A contact lens is located on the surface of the cornea and compensates for the deficiency in focusing power. With the contact lens in place, the patient does not have the difficulties of tunnel vision, the peripheral vision is very much improved and the distortion attendant the thick lens is absent. The difficulties and detriments attendant contact lenses are well known. In example, many people cannot tolerate the feel or sensation of a contact lens on their eye; lens hygiene is a constant problem and the patient must be meticulous about constant cleaning; contact lenses are easily lost. The most significant drawback of contact lenses is the fact that a patient with a cataract is very often a patient in advanced years who does not have the manual dexterity for proper handling of the contact lens. 
     A third alternative of visual rehabilitation is the use of an intraocular lens implant (IOL). An IOL is a small piece of manufactured plastic that is inserted into the eye at surgery. The difficulties enumerated above attendant thick lenses and contact lenses are completely eliminated. Moreover, the patient has no sensation of the presence of the IOL and if the implant is successful, the IOL is in the eye permanently to replace the lost focusing power of the removed crystaline lens. 
     An intraocular lens falls into one of three broad categories depending upon its position within the eye. An anterior chamber untraocular lens is placed within the anterior chamber in front of the iris. Its fixation is dependent on various styles of loops that are supported in the angles of the anterior chamber, whereby the iris tissue is allowed to move freely. From a technical standpoint, the anterior chamber IOL&#39;s are the easiest to implant. The difficulties with prior art anterior chamber IOL&#39;s include: (1) deficient manufacturing methods which leave rough edges of the implant and result in chronic irritation (iritis), elevated intraocular pressure (glaucoma) and bleeding within the anterior chamber (hyphema); (2) the lens support structure is of solid plastic construction, rather than flexible loop construction, which can lead to blockage of the normal aqueous flow within the eye (pupillary block glaucoma); (3) the lack of sufficient flexibility of the support structure leads to difficulties with tenderness on touching of the eye and normal movements during one&#39;s daily activities can lead to chronic irritation whithin the eye; (4) the prior art anterior chamber IOL&#39;s have to be matched in size to the patient&#39;s eye which increases IOL inventory problems. More importantly, without accurate measurements of the patient&#39;s eyes, an inflexible or insufficiently flexible IOL that is too small results in increased movement of the implant that can lead to chronic irritation while an implant that is too large tends to distort the eye, cause discomfort and lead to chronic irritation. The major advantage of an anterior chamber IOL is that it may be used after either intracapsular or extracapsular surgery. 
     An iris supported IOL is an implant that depends on iris tissue or a combination of iris tissue and capsular tissue for its support. It has significant disadvantages because of its lack of uniplanar design, and its constant iris contact. As the present invention is not an iris supported IOL, further discussion of the prior art pertinent to iris supported IOL&#39;s need not be undertaken. 
     A posterior chamber IOL is inserted behind the iris to position the lens in the exact anatomical position of the previously removed cataract or crystaline lens. The major disadvantage of prior art posterior chamber IOL&#39;s is that the cataract must be removed by extracapsular techniques. The advantages attendant posterior chamber IOL&#39;s in general include: (1) fixation at the posterior capsule provides good stability to the eye; (2) as no iris fixation is present, the pupil behaves normally; (3) the implant is uniplanar and therefore is generally easy to insert without damaging other structures; (4) dislocation is rare but if it should occur, the implant does not dislocate anteriorly to damage the cornea; and (5) the patient is visually rehabilitated as nearly as is physiologically possible since the implant is in the exact location as the previously removed crystaline lens. 
     Historically, the earliest posterior chamber IOL implants were performed by Harold Ridley in the late 1940&#39;s. The Ridley biconvex lens was about the same shape as, but had approximately 1 mm smaller diameter than, the normal human lens. Its weight in air was 112 mg, an extremely heavy weight for an object to be implanted in the eye. The weight and relatively large diameter caused the Ridley lens to exert undue pressure on the ciliary body, the annular structure on the inner surface of the eye surrounding the lens and including the ciliary muscle and the ciliary process to which the zonules are connected. Other adverse side effects occurred: glaucoma was noted; in some instances, the lens became loose and fell into the back of the eye; and, many cases of downward decentration were noted, wherein the lens shifted downwardly so that its axis was no longer centered with respect to the pupil. For all of these reasons, the Ridley IOL soon was abandoned. 
     A related IOL designed by Stampelli for use in the anterior chamber was tried in the early 1950&#39;s. This IOL seated in the angle of the eye, where the cornea and iris are joined. Because of poor peripheral design, the use of such IOL&#39;s often caused destruction of the endothelium, a very thin layer of live cells on the interior of the cornea. This is very serious complication, and use of this form of anglefixated anterior chamber IOL soon was stopped. 
     Other attempts have been made to accomplish the objective of fixation without suturing. The Choyce Mark VIII anterior chamber IOL is a thin, generally flat unitary structure having the appearance, when viewed frontally, of an elongated rectangle with rounded corners and notched ends. The rounded corners seat in the angle and center the planoconvex or biconvex optical portion in front of the pupil. The IOL is easy to implant and thus as gained acceptance by many surgeons However, cases of CME have been noted with these IOL&#39;s. Also, because of inflexibility tension is placed on the angle, resulting in tenderness and irritability to the eye, particularly when rubbed. 
     Another form of self-centering IOL was developed by Barraquer, initially for anterior chamber use and later adapted for placement in the posterior chamber. This IOL includes a pair of hook-shaped flexible loops extending from opposite sides of the optical portion. Since one end of each loop is free, the loops would flex sufficiently to snap in place. When installed in the anterior chamber, the hooks seated in the angle. 
     Shearing adapted the Barraquer design for use in the posterior chamber. With extracapsular extraction, the hooks may be implaced within the cleft of the capsule. However, during implantation the hooks are held under tension, and when released may fly up behind the iris and seat directly against the ciliary body. Alternatively, with extracapsular extraction, the hooks may intentionally be installed against the ciliary body. A disadvantage of such an implant is that the hooks continuously exert tension on the ciliary body. An increase in the occurrence of retinal detachments has been noted amongst patients having such Shearing or Barraquer posterior chamber IOL&#39;s. It is likely that the retinal detachments are associated with the tension exerted on the side of the eye in the vicinity of the ciliary sulcus. Furthermore, tenderness also is noted with such an IOL when the eye is rubbed. 
     A further form of posterior chamber of IOL was developed by Pearce. This IOL generally resembles a three-bladed airplane propeller, the blades of which are inserted into the fornix of the capsule after extracapsular extraction. The disadvantage of the IOL is that it is of fixed size and therefore the surgeon must take several different sizes into the operating room; if the first does not fit, he must remove it from the eye and insert another of smaller or larger size. It is also recommended to be sutured for centration. The surgical procedure itself is made unnecessarily complex. 
     Still another form of prior art IOL that is advantageously used with extracapsular surgery is the Binkhorst iridocapsular lens. This is a variant of Binkhorst&#39;s iris clip lens, but it does not have anterior loops. The optical portion itself is centered in the pupil with the rim of the lens lightly touching the front of the iris. The single pair of loops, bent slightly rearward, lie behind the lens and are buried in the iridocapsular cleft. After the surgery, the capsule fibroses or develops iridocapsular adhesions which embed part of the posterior loops, thereby giving extra stability to the implanted lens. 
     Various United States patents directed to various types of IOL&#39;s include the following. U.S. Pat. Nos. 3,906,551 and 3,971,073 illustrate examples of iris supported lenses. U.S. Pat. No. 4,079,470 describes an iris supported IOL and is particularly directed to the material of lenses and coatings therefor. U.S. Pat. No. 4,077,071 is directed to increasing the bouyancy of an IOL implant. U.S. Pat. No. 4,170,043 is also primarily directed to coatings for IOL implants. U.S. Pat. No. 4,168,547 is related primarily to materials for IOL implants. U.S. Pat. No. 4,110,848 is directed to an only slightly flexible posterior chamber IOL implant which must be used in an extracapsular eye. U.S. Pat. No. 4,244,060 describes a posterior chamber IOL implant which employs numerous filaments for supporting the implant. U.S. Pat. No. 4,092,743 is directed to a posterior chamber IOL implant of solid loop material which has no flexibility and the implant can only be used in an extracapsular eye. A variant of the invention, an anterior chamber IOL implant is depicted in FIG. 7 and illustrates an implant presently in production and in use. Either of the types of implants described depend upon three point fixation which method of fixation has been severely critized in the scientific literature because of an often resulting tilting of the lens. Moreover, with three point fixation, one of the ends of the implant can work its way through a peripheral iridectomy and lead to a very unstable lens having only a two point fixation. Little flexibility is available from the implants described and the problems resulting therefrom and enumerated above occur. U.S. Pat. No. 4,174,543 describes an anterior chamber IOL implant, which implant is intended to have flexible support members. However, the configuration and orientation of the support members either preclude flexibility in response to forces exerted radially inwardly within certain angular orientations or within certain relatively significant arcs, depending upon the configuration under examination. The limitations of flexibility of the support members and the resulting lack of compressibility of the proximal segments is a severe limitation on the size of the eye in which any given IOL may be implanted. 
     The intraocular lens implants embodied by the present invention, whether for implantation in the anterior or posterior chamber, incorporate supporting legs or loops of one or more segments At least a segment of each loop is curved and none of the segments of any loop is coincident with a radial of the lens. Thereby, any compressive force exerted radially by the eye upon a point along opposed supporting loops will be accommodated by a bending of one or more segments of each supporting loop. The anterior chamber intraocular lenses may be used after either intracapsular or extra-capsular surgery and the points of fixation of the supporting loops are supported in the angle of the anterior chamber. The posterior chamber intraocular lenses are inserted posterior to the iris in the exact anatomical position of the previously removed cataract, which cataract may be removed by either intracapsular or extracapsular surgery. The points of fixation of the supporting loops are entirely posterior to the iris and anterior to the remaining lens capsule in an extracapsular eye. In an intracapsular eye, at least one of the supporting loops is maneuvered from the posterior chamber to the anterior chamber through a peripheral opening of the iris and fixated in the peripheral portion of the anterior chamber. Manipulation holes or grooves are provided in the proximal segment of the supporting loops an in the lens portion to provide grip for pronged tip forceps prior to and during fixation. The configuration of the supporting loops permit a single size of anterior chamber intraocular lens or posterior chamber intraocular lens to fit any eye size. 
     It is therefore a primary object of the present invention to provide supporting loops for both anterior and posterior chamber intraocular lenses which are sufficiently flexible to accommodate normal imposed compressive forces without any discomfort. 
     Another object of the present invention is to provide a single sized anterior or posterior chamber intraocular lens which may be used in any sized eye within a large range of eye sizes. 
     Still another object of the present invention is to provide an anterior and posterior chamber intraocular lens implant which has a maximum width of six millimeters, the diameter of the lens itself. 
     Yet another object of the present invention is to provide an anterior or posterior intraocular lens implant which has a maximum dimension of 131/2 millimeters and which is compressible to a dimension of 11.5 millimeters with no lens bowing anteriorly or posteriorly. 
     Yet another object of the present invention is to provide anterior and posterior chamber intraocular lens implants which are physically free of the iris and permit normal pupillary movement. 
     A further object of the present invention is to provide a true posterior chamber intraocular lens with no dependence on the pupillary sphincter and useable after either intracapsular or extracapsular cataract removal. 
     A still further object of the present invention is to provide a posterior chamber intraocular lens which may be fixated within the anterior chamber peripherally. 
     A yet further object of the present invention is to provide a posterior chamber intraocular lens which is fixated entirely posterior to the iris and anterior to the remaining lens capsule in an extracapsular eye. 
     A yet further object of the present invention is to provide a posterior chamber intraocular lens implant which is useable in any sized intracapsular to extracapsular eye. 
     These and other object of the present invention will become apparent to those skilled in the art as the description thereof proceeds. 
    
    
     The present invention may be described with greater specificity and clarity with respect to the following drawings, in which: 
     FIG. 1 is a cross-sectional view of a normal eye; 
     FIGS. 2 to 7 illustrate variously configured anterior chamber intraocular lens implants embodying the principles of the present invention; 
     FIG. 8 illustrates a cross-sectional view and implant position of an anterior chamber intraocular lens; 
     FIG. 9 is a plan view of a posterior chamber intraocular lens implant; 
     FIG. 10 illustrates a cross-sectional view of a posterior chamber intraocular lens; 
     FIG. 11 illustrates the implant position of a posterior chamber intraocular lens in an extracapsular eye; and 
     FIG. 12 illustrates the implant position of a posterior chamber intraocular lens in an intracapsular eye. 
    
    
     Referring to FIG. 1, a normal eye will be briefly described. Cornea 12 is a clear transparent tissue which acts as a transmissive element for light. It also has some capability for focusing the transmitted light upon the retina (not shown). The light transmitted through the cornea passes through anterior chamber 14 and the fluid disposed therein and impinges upon a crystaline lens 16. The lens acts as a major focusing element for the light penetrating therethrough upon the retina. A fluid known as vitreous humor is a light transmitting medium intermediate the lens and the retina. Lens 16 is encased within a capsule 18. Iris 20 is disposed anterior of lens 16 and serves in the nature of a diaphragm to regulate the amount of light impinging upon the lens. 
     When cataract occurs, clouded areas form within the lens. These clouded areas affect the transmissivity of light therethrough and impair sight. When the cloud becomes sufficiently severe, the only treatment available is surgical removal of the lens itself. Such removal is referred to as extracapsular cataract surgery (extracapsular eye) when capsule 18 remains either partially or entirely intact within the eye. Removal of the lens together with the supporting capsular tissue or capsule 18 is referred to as intracapsular cataract surgery (intracapsular eye). 
     FIGS. 2 through 7 illustrate various anterior chamber intraocular lens implants and FIGS. 9 and 10 illustrate a posterior chamber intraocular lens implant, any of which may be used to replace a lens 16 removed by either intracapsular or extracapsular cataract surgery. Each of these implants includes an optical portion having a plano-convex surface with the convex surface facing anteriorly. Nominally, the optical portion is 6 millimeters in diameter. Supporting loops having a nominal width of 0.25 millimeters extend in generally diametrically opposed directions from the optical portion. These supporting loops and the optical portion may be of one piece construction of separate pieces with the supporting loop firmly inserted into the optical portion at a predetermined angle and orientation. The major dimension across the implant diameter is nominally 13.5 millimeters and the width is no more than that of the lens, 6 millimeters. The material of the implants may be of polymethylmethacrylate or other nonabsorbable nontoxic sterile material. 
     Referring to FIG. 2, there is shown a lens portion 30 retained in place by supporting loops 32 and 34. The supporting loops are mirror images of one another in both configuration and size. Each segment 36 is curved and extends from a point essentially tangential to optical portion 30. Segment 38 is curved interiorly toward the optical portion from between fixation points 40 and 42, the latter also being the junction with segment 36. Both fixation points are smoothly rounded to preclude abrading and irritating the point of contact with the eye. By inspection, it will become apparent that any compressive force imposed upon any two points of fixation will result in bending of any intermediate segments and compliance with any such imposed compressive force does not depend upon compression or elongation of a segment along its longitudinal axis. 
     FIG. 3 illustrates a lens portion 44 having supporting loops 46, 48 extending tangentially from diametrically opposed locations on the lens portion. Since the supporting loops are identical but reversely oriented, a description of one will apply to the other. Segment 50 of supporting loop 46 extends tangentially from the edge of lens portion 44 and thereafter curves somewhat concentrically with the lens portion through a substantial arc whereafter it extends exteriorly in general parallel laterally offset relationship with a radial of the lens portion bisecting the curved part of the segment. Segment 52 extends perpendicularly from the extremity of segment 50 for a distance approximately equal with the diameter of the lens portion. The junction between the two segments and the extremity of segment 52 are curved smooth surfaced and define fixation points 54, 56. 
     By inspection, it will become apparent that any compressive force imposed intermediate the fixation points of supporting loop 46 and 48 will result in bending of two or more of the segments. Moreover, compliance with such compressive force is not dependent upon compression or elongation of any segment along its longitudinal axis. It may be noted that upon application of a compressive force intermediate fixation points of supporting loops 46 and 48, some counter-clockwise rotation of lens 44 may occur. Such rotation has no effect upon the optics of the lens portion and the patient will be unaware of it. 
     FIG. 4 illustrates a lens portion 58 having diametrically opposed supporting loops, 60, 62. Each supporting loop includes a pair of exteriorly oppositely curved segments 64, 66. The segments are terminated by bulbous ends which serve as fixation points 68, 70, respectively. The configuration of the segments of supporting loops 60 and 62 provide compliance with any compressive force exerted intermediate any two fixation points by bending of the intermediate segments. The overall flexibility of this implant may be somewhat less than that of the implants described above because of the diametrically opposed junctions in combination with the radially centered disengaging orientation of each pair of segments. 
     The implant illustrated in FIG. 5 is a direct variant of that shown in FIG. 4. Herein, lens portion 72 includes a pair of diametrically opposed supporting loops 74, 76. Each loop includes segments 78, 80 diverging from a junction. Each segment includes a curved section and a straight section extending from the extremity of the curved section and along a ling parallel to and offset of a radial of the lens portion passing through the junction of the relevant supporting loop. The bulbous end of each straight section of segments 78, 80 serves as a fixation point 82, 84. 
     FIG. 6 illustrates an anterior chamber intraocular lens implant which includes a lens portion 82 retained in place by a supporting loop 32 in the type described with respect to FIG. 2. A second supporting loop, located in diametrically opposed relationship thereto may be of the configuration of supporting loop 60 shown in FIG. 4 or supporting loop 74 shown in FIG. 5. 
     FIG. 7 illustrates an anterior chamber intraocular lens having a lens portion 84 supported by a supporting loop 46 of the type described with respect to FIG. 3. The diametrically oriented opposed supporting loop may be either supporting loop 60 shown in FIG. 4 or supporting loop 74 shown in FIG. 5. 
     Referring to FIG. 8, there is shown an anterior chamber intraocular lens implant 90 located within eye 10. The selection of implant 90 may be any one of the type illustrated in FIG. 2 through 7, the selection of which is dependent upon various criteria not presently germain. To insure a noncontacting relationship between the implant and iris 20, a vault of approximately 0.5 millimeters is formed between the planoposterior surface 94 of lens portion 92 and posterior surfaces 96, 98 attendant the extremities of supporting loops 100, 102. As illustrated, implant 90 is supported by the fixation points 104, 106 in angles 108, 109 within the anterior chamber. It may be noted that eye 10 is illustrated as having undergone intracapsular cataract surgery although it is to be understood implantation could as easily have been accomplished had the eye undergone extracapsular cataract surgery. 
     Referring jointly to FIGS. 9 and 10, there is shown a posterior chamber intraocular lens implant 110. The structure of this implant permits implantation within the posterior chamber of any sized eye and irrespective of whether the cataract has been removed by extracapsular or intracapsular surgery. A pair of supporting loops 112, 114, extend tangentially in opposed directions from the perimeter of lens portion 116. In the embodiment illustrated, the supporting loops are mirror images of one another and only one of them will be described in detail. Supporting loop 112 includes a segment 118 which is curved interiorly toward lens portion 116. A further segment 120 extends from the extremity of segment 118 and is folded back upon it; this segment is also curved interiorly toward lens portion 116 and may be concentric therewith. It may be curved as shown to provide an infinite number of fixation points. As particularly illustrated in FIG. 10, supporting loops 112 and 114 may lie in the same plane as the plane of the planoconvex lens portion 116. Alternatively, the supporting loops may be set at an angle of approximately 10° with respect to the posterior plane of the lens portion, as illustrated in FIG. 12. 
     The fixation of implant 110 in an extracapsular eye is particularly illustrated in FIG. 11. Herein, there is depicted an eye 122 upon which extracapsular surgery has been performed leaving posterior capsule 126. Supporting loops 112, 114, extending from lens 116 of implant 110 are fixated anterior to capsule 126 within a sulcus or groove 130 posterior of iris 20 and at the pupillary periphery; it does not affect pupillary movement. 
     FIG. 12 illustrates a posterior chamber intraocular lens implant 140 having supporting loops 142, 144 extending in diametrically opposed directions from lens 146. The loops extend forwardly, that is toward the convex surface of the lens, at an angle of approximately 10° with respect to the plane defined by the planar surface of the lens. Implant 140 is shown fixated within an eye 148 which has undergone intracapsular surgery. The segments are either fixated posteriorly with the aid of a non-absorbable fixation suture through iris tissue in the periphery or the segments are manipulated from the posterior chamber to the anterior chamber through a peripheral iridotomy for fixation in the anterior chamber. Segments 120 (see FIG. 9) of supporting loops 142, 144 have been maneuvered from the posterior chamber to the anterior chamber through a peripheral opening of the iris (iridotomy or iridectomy) and fixated in the peripheral portion of the anterior chamber. In either case, the optical portion of the implant remains in the posterior chamber and the points of fixation are at or in proximity to the pupillary periphery to avoid affecting the pupillary movement. It is to be understood that the description above is also applicable to posterior chamber intraocular lens implants in which the supporting loop are not angulated. 
     As particularly noted in FIG. 9, apertures 150 are disposed in segments 118 of the supporting loops; alternatively, the apertures may be replaced by a radially inwardly oriented depression or groove 152, as shown on segment 118a. These apertures or grooves, in combination with apertures 154 in the lens, are engageable with pronged tips of forceps to permit compressing of the supporting loops to ease manipulation of the implant into the posterior chamber. 
     While the posterior chamber intraocular lens implant is illustrated in FIGS. 11 and 12 as being generally vertically oriented (note FIG. 9), horizontal orientation is possible Moreover, horizontal orientation for intracapsular eyes positions segments 120 such that penetration through the iris occurs at the ten and two o&#39;clock positions of the eye. 
     Upon fixation of the posterior chamber intraocular lens implant, essentially all of segments 120 are disposed in the anterior chamber while essentially all of segments 118 are disposed posterior of iris 20 such that the junction between the segments is coincident with the respective peripheral openings in the iris. 
     A primary advantage of the posterior chamber intraocular lens implant described with particular reference to FIGS. 9 through 12 is that it provides a single sized uniplanar implant that can be used in any sized eye. Furthermore, it retains all of the advantages of a posterior chamber intraocular lens implant and is also suitable for use in an eye which has undergone either extracapsular surgery or intracapsular surgery. Moreover, the disadvantages inherently attendant either anterior chamber intraocular lens implants or iris supported lenses are avoided. 
     While the principles of the invention have now been made clear in an illustrative embodiment, there will be immediately obvious to those skilled in the art many modifications of structure, arrangement, proportions, elements, materials, and components, used in the practice of the invention which are particularly adapted for specific environments and operating requirements without departing from those principles: