Abstract:
A flexible accommodating intraocular lens having anteriorly and posteriorly movable extended portions, such as T-shaped haptics, extending from a central solid biconvex optic to be implanted within a natural capsular bag of a human eye with the extended portions positioned between an anterior capsular rim and a posterior capsule of the bag, whereby during a post-operative healing period, fibrosis occurs about the extended portions to fixate the lens in the bag in a manner such that subsequent natural contraction and relaxation of the ciliary muscle moves the optic to provide vision accommodation. A surface of the optic is a toric surface.

Description:
[0001]    This application is a continuation of application Ser. No. 10/454,280, filed Jun. 3, 2003, which is a continuation of Ser. No. 10/057,691, filed on Jan. 24, 2002, which is a division of application Ser. No. 08/858,978, filed on May 20, 1997, now U.S. Pat. No. 6,387,126, which is a continuation-in-part of application Ser. No. 08/388,735, filed on Feb. 5, 1995, now abandoned, the disclosures of which are incorporated by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates generally to intraocular lenses to be implanted within a natural capsular bag in the human eye formed by evacuation of the crystalline matrix from the natural lens of the eye through an anterior capsulotomy in the lens. The invention relates more particularly to novel accommodating intraocular lenses of this kind having improved features including an optic with a toric posterior surface.  
           [0003]    The human eye has an anterior chamber between the cornea and iris, a posterior chamber behind the iris containing a crystalline lens, a vitreous chamber behind the lens containing vitreous humor, and a retina at the rear of the vitreous chamber. The crystalline lens of a normal human eye has a lens capsule attached about its periphery to the ciliary muscle of the eye by zonules and containing a crystalline lens matrix. This lens capsule has elastic optically clear anterior and posterior membrane-like walls commonly referred to by ophthalmologists as anterior and posterior capsules, respectively. Between the iris and the ciliary muscle is an annular crevice-like space called the ciliary sulcus.  
           [0004]    The human eye in patients under the age of 45 years possesses natural accommodation capability. Natural accommodation capability involves relaxation and contraction of the ciliary muscle of the eye by the brain to provide the eye with near and distant vision. This ciliary muscle action is automatic and shapes the natural crystalline lens to the appropriate optical configuration for focusing on-the retina the light rays entering the eye from the scene being viewed.  
           [0005]    The human eye is subject to a variety of disorders which degrade or totally destroy the ability of the eye to function properly. One of the more common of these disorders involves progressive clouding of the natural crystalline lens matrix resulting in the formation of what is referred to as a cataract. It is now common practice to cure a cataract by surgically removing the cataractous human crystalline lens and implanting an artificial intraocular lens in the eye to replace the natural lens. The prior art is replete with a vast assortment of intraocular lenses for this purpose.  
           [0006]    Intraocular lenses differ widely in their physical appearance and arrangement. This invention is concerned with intraocular lenses of the kind having a central optical region or optic and portions which extend outward from the optic and engage the interior of the eye in such a way as to support the optic on the axis of the eye.  
           [0007]    Intraocular lenses also differ with respect to their accommodation capability and their placement in the eye. Accommodation is the ability of an intraocular lens to accommodate, that is, to focus the eye for near and distant vision. Certain patents describe alleged accommodating intraocular lenses. Other patents describe non-accommodating intraocular lenses. Most non-accommodating lenses have immobile single focus optics which focus the eye at a certain fixed distance only and require the wearing of eye glasses to change the focus. Other non-accommodating lenses have bifocal optics which simultaneously image both near and distant objects on the retina of the eye. The brain selects the appropriate image and suppresses the other image, so that a bifocal intraocular lens provides both near vision and distant vision sight without eyeglasses. Bifocal intraocular lenses, however, suffer from the disadvantage that each bifocal image represents only about 40% of the available light, and a remaining 20% of the light is lost in scatter.  
           [0008]    There are four possible placements of an intraocular lens within the eye. These are (a) in the anterior chamber, (b) in the posterior chamber, (c) in the capsular bag, and (d) in the vitreous chamber. The intraocular lens disclosed herein is for placement in the capsular bag.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention relates to accommodating intraocular lenses having a central optic and haptics, and wherein a surface, preferably the posterior or back surface, of the optic is a toric surface.  
           [0010]    This invention provides an improved accommodating intraocular lens to be implanted within a capsular bag of a human eye which remains intact within the eye after removal of the crystalline lens matrix from the natural lens of the eye through an anterior capsule opening in the natural lens. An improved accommodating intraocular lens according to the invention includes a central optic having normally anterior and posterior sides and extended portions spaced circumferentially about and extending generally radially out from the edge of the optic. Importantly, the posterior or back surface of the optic is a toric surface. These extended portions have inner ends joined to the optic and opposite outer ends movable anteriorly and posteriorly relative to the optic. To this end, the extended portions may be either pivotally or flexibly hinged at their inner ends to the optic or are resiliently bendable throughout their length or may be relatively rigid. The terms “flex”, “flexing”, “flexible”, and the like are used in a broad sense to cover both flexibly hinged and resiliently bendable extended portions. The terms “hinge”, “hinged”, “hinging”, and the like are used in a broad sense to cover both pivotally and flexibly hinged extended portions.  
           [0011]    The lens is surgically implanted within the evacuated capsular bag of a patient&#39;s eye through the anterior capsule opening in the bag and in a position wherein the lens optic is aligned with the opening, and the outer ends of the lens extended portions are situated within the outer perimeter or cul-de-sac of the bag. The lens has a radial dimension from the outer end of each extended portion to the axis of the lens optic such that when the lens is implanted within the capsular bag, the outer ends of the extended portions engage the inner perimetrical wall of the bag without unnecessarily stretching the bag.  
           [0012]    As is known, after surgical implantation of the accommodating intraocular lens in the capsular bag of the eye, active endodermal cells on the posterior side of the anterior capsule rim of the bag cause fibrosis with shrinkage of the bag and fusion of the rim to the elastic posterior capsule of the bag. This fibrosis occurs about the lens extended portions in such a way that these extended portions and the lens are effectively “shrink-wrapped” by the fibrous tissue in such a way as to form radial pockets in the fibrous tissue which contain the extended portions with their outer ends positioned within the outer cul-de-sac of the capsular bag. The lens is thereby fixated within the capsular bag with the lens optic aligned with the anterior capsule opening in the bag. The anterior capsule rim shrinks during fibrosis, and this shrinkage combined with shrink-wrapping of the extended portions causes some radial compression of the lens in a manner which tends to move the lens optic relative to the outer ends of the extended portions posteriorly along the axis of the eye. The fibrosed, leather-like anterior capsule rim prevents anterior movement of the optic and urges the optic rearwardly during fibrosis. Accordingly, fibrosis induced movement of the optic occurs posteriorly to a distant vision position in which either or both the optic and the inner ends of the extended portions press rearwardly against the elastic posterior capsule of the capsular bag and stretch this posterior capsule rearwardly.  
           [0013]    During surgery, the ciliary muscle of the eye is paralyzed with a ciliary muscle relaxant, i.e. a cycloplegic, to place the muscle in its relaxed state. Following surgery, a ciliary muscle relaxant, a cycloplegic, is introduced into the eye to paralyze the ciliary muscle throughout the post-operative fibrosis and healing period (from two to three weeks) to maintain the ciliary muscle in its relaxed state until fibrosis is complete. This drug-induced relaxation of the ciliary muscle prevents contraction of the ciliary muscle and immobilizes the capsular bag during fibrosis. By this means, the lens optic is fixed during fibrosis in its distant vision position within the eye relative to the retina wherein the lens presses rearwardly against and thereby posteriorly stretches the elastic posterior capsule of the capsular bag. If the ciliary muscle was not thus maintained in its relaxed state until the completion of fibrosis, the ciliary muscle would undergo essentially normal brain-induced vision accommodation contraction and relaxation during fibrosis. This ciliary muscle action during fibrosis would result in improper formation of the pockets in the fibrosis tissue which contain the extended portions of the lens. Moreover, ciliary muscle contraction during fibrosis would compress the capsular bag and thereby the lens radially in such a way as to very likely dislocate or decenter the lens from its proper position in the bag or fix the optic in the near vision position.  
           [0014]    When the cycloplegic effect of the ciliary muscle relaxant wears off after the completion of fibrosis, the ciliary muscle again becomes free to undergo normal brain-induced contraction and relaxation. Normal brain-induced contraction of the muscle then compresses the lens radially, relaxes the zonules and anterior capsule rim, and increases vitreous pressure in the vitreous cavity of the eye. This normal contraction of the ciliary muscle effects anterior accommodation movement of the lens optic for near vision by the combined action of the increased vitreous pressure, anterior capsule rim relaxation, and the anterior bias of the stretched posterior capsule. Similarly, brain-induced relaxation of the ciliary muscle reduces vitreous pressure, relieves radial compression of the lens, and stretches the anterior capsule rim to effect posterior movement of the lens optic for distant vision.  
           [0015]    Normal brain-induced contraction and relaxation of the ciliary muscle after the completion of fibrosis thus causes anterior and posterior accommodation movement of the lens optic between near and distant vision positions relative to the retina. During this accommodation movement of the optic, the lens extended portions may undergo endwise movement within their pockets in the fibrous tissue.  
           [0016]    The described lens embodiments of the invention conform to one of the following basic lens configurations:  
           [0017]    A. A flexible lens body configuration wherein the extending portions and optic are all flexible and the extending portions and optic are in the same plane. This lens after implantation in the eye and after paralyzing the ciliary muscle for two to three weeks, undergoes natural posterior location in the capsular bag space due to end-wise compression and shrink-wrapping of the lens by fibrosis of the anterior capsule.  
           [0018]    B. A lens configuration such that the lens body is flexible throughout the extending portions and optic such that the lens optic before implantation is located behind the outer ends of the extending portions such that the optic can move backwards and forwards along the axis of the eye relative to the outer ends of the haptics. This movement can be such that the optic never moves anteriorly to the outer ends of the extending portions, that it moves from a posterior position to a position which makes it uniplanar to the outer ends of the extending portions, or such that it moves from a posterior position to a position anterior to the outer ends of the extending portions.  
           [0019]    C. An accommodating flexible intraocular lens whereby the extended portions and optic are flexible, wherein the optic is located anteriorly to the outer ends of the extended portions prior to implantation within the eye. The lens is configured such that, with constriction of the ciliary muscle, the optic will move anteriorly relative to the outer ends of the extended portions and posteriorly upon relaxation of the ciliary muscle relative to the outer end of the extended portions. The optic may or may not move to the same plane as or behind the outer ends of the extended portions. The three embodiments described above may have a reduced thickness portion of the extended portion adjacent to the optic comprising a thinned portion or a groove, or the extended portions adjacent to the optic may be resiliently flexible without having a hinged or thin portion. Should the material from which the lens is made be relatively rigid, then the whole lens itself may move backwards and forwards without there being any flexion at the optic flexible portion junction. The movement of the lens alone or the lens optic relative to the outer ends of the extended portions may be caused by one or a combination of the following: constriction and relaxation of the ciliary muscle, increase and decrease of vitreous cavity pressure, the resilience of the posterior capsule, and end-wise compression and relaxation of the lens by the ciliary muscle through the capsular bag wall.  
           [0020]    The extended portions of a presently preferred lens embodiment are generally T-shaped haptics each including a haptic plate and a pair of relatively slender resiliently flexible fixation fingers at the outer end of the haptic plate. In their normal unstressed state, the two fixation fingers at the outer end of each haptic plate extend laterally outward from opposite edges of the respective haptic plate in the plane of the plate and substantially flush with the radially outer end edge of the plate to form the horizontal “crossbar” of the haptic T-shape. The radially outer end edges of the haptic plates are circularly curved about the central axis of the lens optic to substantially equal radii closely approximating the radius of the interior perimeter of the capsular bag when the ciliary muscle of the eye is relaxed. During implantation of the lens in the bag, the inner perimetrical wall of the bag deflects the haptic fingers generally radially inward from their normal unstressed positions to arcuate bent configurations in which the radially outer edges of the fingers and the curved outer end edges of the respective haptic plates conform approximately to a common circular curvature closely approximating the curvature of the inner perimetrical wall of the bag. The outer T-ends of the haptics then press lightly against the perimetrical bag wall and are fixated within the bag perimeter during fibrosis with approximation of the anterior capsule to the posterior capsule to accurately center the implanted lens in the bag with the lens optic aligned with the anterior capsule opening in the bag.  
           [0021]    The haptic plates of certain described lens embodiments are narrower in width than the optic diameter and are tapered so as to narrow in width toward their outer ends. These relatively narrow plates of the haptics flex or pivot relatively easily to aid the accommodating action of the lens and form haptic pockets of maximum length in the fibrous tissue between the haptic fingers and the optic which maximize the accommodation movement of the lens optic. The tapered haptics, being wider adjacent to the optic, can slide radially in the capsular bag pockets during contraction of the ciliary muscle to enable forward movement of the optic for vision accommodation.  
           [0022]    In a lens embodiment of the invention, the lens optic and extended portions, which may be plates, are molded or otherwise fabricated preferably as an integral one piece lens structure in which the inner ends of the extended portions are integrally joined to the optic, and the extended portions have flexible hinges at their inner ends adjacent the optic at which the extended portions are hingable anteriorly and posteriorly relative to the optic. The extended portions are T-shaped haptics formed by embedding flexible haptic fingers on loops with the haptic plates proper. In particular, the optic has a toric posterior surface.  
           [0023]    Accordingly, it is a principal object of the present invention to provide an improved toric accommodating lens. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    [0024]FIG. 1 is a plan view of the lens according to the present invention,  
         [0025]    [0025]FIG. 2 is a side view thereof, and  
         [0026]    [0026]FIG. 3 is a view showing the lens as implanted.  
         [0027]    [0027]FIG. 4 is a view showing a plate embodiment of the toric lens.  
         [0028]    [0028]FIG. 5 is a view of a lens with multi extended portions.  
         [0029]    [0029]FIG. 6 is an alternative embodiment. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0030]    Turning now to the drawings and first to FIG. 3, the capsular bag (not shown) includes an annular anterior capsular remnant or rim  22 . The capsular rim  22  is the remnant of the anterior capsule of the natural lens which remains after capsulorhexis has been performed on the natural lens. This rim circumferentially surrounds a central, general round anterior opening  26  (capsulotomy) in the capsular bag through which the natural lens matrix was previously removed from the natural lens. The capsular bag is secured about its perimeter to the ciliary muscle via the zonules which are not shown.  
         [0031]    Implanted within the capsular bag of the eye is an accommodating intraocular lens  32  according to this invention which replaces and performs the accommodation function of the removed human crystalline lens. The accommodating intraocular lens may be utilized to replace either a natural lens which is virtually totally defective, such as a cataractous natural lens, or a natural lens that provides satisfactory vision at one distance without the wearing of glasses but provides satisfactory vision at another distance only when glasses are worn. For example, the accommodating intraocular lens of the invention can be utilized to correct refractive errors and restore accommodation for persons in their mid-40s or older who require reading glasses or bifocals for near vision.  
         [0032]    Intraocular lens  32  comprises a flexible unitary lens body, including a flexible biconvex solid optic  34 , which may be formed of relatively hard material, relatively soft flexible semi-rigid material, or a combination of both hard and soft materials. Examples of relatively hard materials which are suitable for the lens body are methyl methacrylate, polysulfones, and other relatively hard biologically inert optical materials. Examples of suitable relatively soft materials for the lens body are silicone, hydrogels, thermolabile materials, and other flexible semi-rigid biologically inert optical materials.  
         [0033]    The lens  32  includes the central optic  34  and T-shaped extended portions or plate haptics  36  extending from diametrically opposite edges of the optic. Importantly, the posterior surface  34   b  (FIG. 2), is a toric surface and the anterior surface  34   a  may have any suitable curvature such as spherical. The toric surface  34   b  may be on either the posterior or anterior surface and allows for correction of astigmatism. Since the toric surface is irregular as contrasted to a spherical surface, the lens can include some indicia to facilitate proper insertion and orientation in the eye. The fingers  36   b  preferably have enlarged ends  36   c  as seen in FIG. 1.  
         [0034]    The haptics include haptic members or plates  36   a  having inner ends joined to the optic and opposite outer free ends and lateral fixation fingers or loops  36   b  at their outer ends. The loops  36   b  are attached at  36   d  (like arrow heads) to the outer ends of the plates  36   a . The loops  36   b  may be of a different but flexible material.  
         [0035]    The haptic plates  36   a  preferably are longitudinally tapered so as to narrow in width toward their outer ends and may have a width throughout their length less than the diameter of the optic  34 , and may be resiliently flexible for major portions of their lengths. The haptics  36  are movable anteriorly and posteriorly relative to the optic  34 , that is to say the outer ends of the haptics are movable anteriorly and posteriorly relative to the optic. The preferred lens embodiment illustrated is constructed of a resilient semi-rigid material and has flexible hinges  38  which join the inner ends of the haptic plates  36   a  to the optic. The haptics are relatively rigid and are flexible about the hinges anteriorly and posteriorly relative to the optic as shown in FIGS. 1 and 2. These hinges are formed by grooves  40  which can be either on the anterior, posterior, or both sides and extend across the inner ends of the haptic plates  36   a . In the present preferred embodiment the grooves  40  are in the anterior side as seen in FIG. 2. The haptics  36  are flexible about the hinges  38  in the anterior and posterior directions of the optic. The lens has a relatively flat unstressed configuration, illustrated in FIG. 2 wherein the haptics  36  and their hinges  38  are disposed in a common plane transverse to the optic axis of the optic  34 . Deformation of the lens from this normal unstressed configuration by anterior or posterior deflection of the haptics about their hinges creates in the hinges elastic strain energy forces which urge the lens to its normal unstressed configuration. The outer end edges  41  of the haptic plates  36   a  are preferably slightly curved about the optic axis of the optic  34 , as shown in FIG. 1. In their normal unstressed state shown in solid lines in FIG. 1, the fixation loops  36   b  of each plate haptic  36  extend laterally out from opposite longitudinal edges of the respective haptic plate  36   a  in the plane of the plate and substantially flush with the outer end edge  41  of the plate. When unstressed, the loops  36   b  are preferably straight or slightly bowed with a slight radially inward curvature, as shown in solid lines in FIG. 1. As shown in broken lines in FIG. 3, the loops  36   b  are laterally resiliently flexible radially of the haptic plates  36   a  to their broken line positions of FIG. 3 in which the radially outer edges of the fingers and the end edges  41  of the haptic plates  36   a  conform substantially to a common circle centered on the axis of the optic  34 .  
         [0036]    An accommodating toric intraocular lens  52  according to FIG. 4 which comprises a biconvex solid optic  54  with plate extending portions  56 , having raised shoulders  58  on one or both sides at the distal ends of the extended portions. The extending portions  54  may have a groove or hinge  55  across their surfaces adjacent to the optic or may be resiliently flexible at the juncture of the optic and extended portions.  
         [0037]    [0037]FIG. 5 illustrates an accommodating toric intraocular lens  62  which has an optic  64  and four extending portions  66 , which in this instance comprise plates with fixation centration devices  69  at their distal ends. These fixation devices may comprise raised shoulders  68  on one or both sides of the extended portions  66 . The junction of the extended portions, which may be plates, has a thinned area or a groove  65  adjacent to the optic  64  or may just be resiliently flexible at the junction of the plate extended portion to the optic.  
         [0038]    [0038]FIG. 6 illustrates an alternative embodiment of a lens  70  wherein the extending portions or haptics are in the form of thin members  72  extending from the optic  74 . Centration/fixation loops  80  can be added to both outer ends or not added as desired, and likewise hinges  75  as shown can be provided on both sets of haptics or omitted from both as desired. Furthermore, knobs  78  can be provided at the ends of loops  80  or omitted. While embodiments of the present invention have been shown and described, various modifications may be made without departing from the scope of the present invention, and all such modifications and equivalents are intended to be covered.