Abstract:
An accommodating intraocular lens comprising a flexible body, a flexible optic which is moveable anteriorly and posteriorly relative to the lens body, and hinged portions longitudinally connecting the optic to the body. The body may have extending centration and fixation loops on its distal ends.

Description:
This application is a continuation-in-part of application Ser. No. 11/620,488 filed Jan. 5, 2007, which is a continuation-in-part of Ser. No. 11/459,862 filed on Jul. 25, 2006 now abandoned, both of which are fully incorporated herein by reference. 
    
    
     BACKGROUND 
     Intraocular lenses have for many years had a design of a single optic with loops attached to the optic to center the lens and fixate it in the empty capsular bag of the human eye. In the mid &#39;80s plate lenses were introduced, which comprised a silicone lens, 10.5 mm in length, with a 6 mm optic. These lenses could be folded but did not fixate well in the capsular bag, but resided in pockets between the anterior and posterior capsules. The first foldable lenses were all made of silicone. In the mid 1990s an acrylic material was introduced as the optic of lenses. The acrylic lens comprised a biconvex optic with a straight edge into which were inserted loops to center the lens in the eye and fixate it within the capsular bag. 
     Recently accommodating intraocular lenses have been introduced to the market, which generally are modified plate haptic lenses. A plate haptic lens may be defined as an intraocular lens having two or more plate haptics where combined junctions with the optic represent one quarter or more of the circumference of the optic. 
     Flexible acrylic material has gained significant popularity among ophthalmic surgeons. In 2003 for example more than 50% of the intraocular lenses implanted had acrylic optics. Hydrogel lenses have also been introduced. The acrylic materials are incapable of multiple flexions without fracturing. 
     The advent of an accommodating lens which functions by moving the optic along the axis of the eye by repeated flexions somewhat limited the materials from which the lens could be made. Silicone is the ideal material, since it is flexible and can be bent probably several million times without showing any damage. Additionally one or more grooves or hinges can be placed across the plate adjacent to the optic as part of the lens design to facilitate movement of the optic relative to the outer ends of the haptics. An example accommodating lens of this nature is disclosed in U.S. Pat. No. 6,387,126 in the name of J. Stuart Cumming. 
     SUMMARY OF THE INVENTION 
     According to the present invention a new form of accommodating intraocular lens having a lens body and optic is provided with plural straps, preferably two, between the optic and lens body to allow the optic to move anteriorly and posteriorly in response to the pressure gradient created with accommodation. The lens body preferably has a central hinge. The structure is such that it particularly benefits from changes in vitreous pressure with accommodation. 
     The lens body is shaped such that it is wider centrally than it is on its peripheral end. The end of the lens body, after implantation into the eye, is held in position by a pocket formed by fusion of the anterior and posterior bag walls. Upon ciliary muscle constriction the zonules attaching the capsular bag to the ciliary muscle relax and the vitreous pressure increases. The hinged lens body surrounding the optic cannot move peripherally into the smaller pocket. The fibrosed capsular bag thus exerts end to end pressure on the ends of the posteriorly vaulted lens, pushing the posteriorly vaulted two lens body parts back into the vitreous further increasing the vitreous cavity pressure. This increase in pressure plus the increase caused by cilary muscle contraction with redistribution of its mass, urges the optic forward. The thin straps and thus hinges, especially the base of the hinges, stretch like a rubber band further facilitating anterior movement of the lens (See.  FIG. 9 ). 
     Thus, it is a feature of the present invention to provide a new form of accommodating lens. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1   a  is a prospective view of the front or anterior side of the lens according to the present invention. 
         FIG. 1   b  is a prospective view of an alternative embodiment. 
         FIG. 2  is a plan view of the anterior side. 
         FIG. 3  is a plan view of the back or posterior side of the lens. 
         FIG. 4  is a side view. 
         FIG. 5  is an end view. 
         FIG. 6  is a cross-sectional view along lines  6 - 6  of  FIG. 2 . 
         FIG. 7  is a perspective view of the back or posterior side of the lens. 
         FIG. 8  is a side view during distance vision. 
         FIG. 9  is a side view during near vision. 
         FIGS. 10-12  illustrate a “W” concept with  FIG. 10  showing a conventional lens, and  FIGS. 11-12  generally illustrating the present lens with a wide hinge base and additional hinges to allow the lens to move to a “W” shape. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     Turning now to the drawings,  FIG. 1   a  is a perspective view of the present lens  10  including a lens body or plate  12  and optic  14 . The body  12  includes haptics  15  which are wider centrally thus preventing them from moving peripherally into a smaller bag pocket upon ciliary muscle contraction. The body  12  and optic  14  are formed of silicone or other suitable flexible material. Straps  16  are provided between the body  12  and the periphery or outer diameter of the optic  14 . Each strap preferably includes one or two hinges  17  on the anterior side of the lens, or no hinges. The straps may be 0.5 mm long in the radial direction and 0.25 mm thick to support the optic  14  by the straps  16 . The optic  14  typically can have a diameter of 4.5-5.0 mm, a typical width of the overall lens  10  on the short side is 6.1 mm and the typical length from end to end (not including fixation fingers) on the long side is 10.5-11.5 mm. A typical optic thickness is 0.4-1.3 mm. 
     The body  12  and optic  14 , as well as outer thickened footplate ends  20 , are formed of silicone or other suitable flexible material. The lens  10  also preferably includes fixation loops  24  of polymide or similar material. A typical outer loop-to-loop length is 11.0-12.5 mm. The thickened ends  20  fully engulf the fixation loops  24  in the silicon thus to provide a strong matrix to hold the loops  24 . There is an additional function of these thickened areas of the plate. They also serve to elevate the anterior capsule of the human lens away from the optic and from the posterior capsule after the cataract has been removed and the lens implanted. This may serve to reduce capsular opacification and contraction. The haptics  15  can be any typical shape, such as in the present Figures, rectangular, triangular, or the like. 
     The straps  16  and hinges  17  function by allowing the optic to move anteriorly and posteriorly. The approximately 1.0-2.0 mm wide straps are a point of relative weakness in the plane of the lens body  12  encircling the optic  14 , thereby allowing the entire optic  14  to herniate forward (anteriorly) from its far posterior position in a translational forward movement. This feature is enhanced by keeping the mass of the optic  14  to a minimum as described below. This new mechanism may boost the effect of the other features of the lens. Rather than a fluid-filled sac pushing through an aperture as in some prior lenses, the present lens involves a deformable solid optic moving anteriorly and posteriorly through a hinged area  16  in the plate or body  12 . Central hinges  18  on the anterior side of the body  12  hinging the haptics  15  further facilitate movement of the optic with ciliary muscle contraction.  FIG. 1   b  shows an alternative embodiment with a pair of hinges  51  as shown in alignment with the edges of the optic rather than the hinges  18 . 
     Of significance is the manner in which the optic  14  and haptic plates  15  move in accommodating from distance to near vision and this is particularly illustrated in  FIGS. 8 and 9  with respect to anterior A and posterior B reference lines in these Figs. As is usual, the ends of the haptics  15  or the loops  24  as the case may be are implanted in the capsular bag such that the optic  14  is vaulted posteriorly for distance vision as seen in  FIG. 8 . The optic  14  moves anteriorly for near vision as shown in  FIG. 9  upon ciliar muscle contraction. In particular, the whole lens moves forward a little as seen in  FIG. 9  and the haptic plates  15  move centrally and backward slightly in the direction of arrows  44  which results in a pressure caused by ciliary muscle contraction to further increase pressure on the optic  14  that pushes the optic further forward because the hinge or hinges  17  are thin and stretch a little and the optic deforms somewhat. This provides an increase in anterior optic movement with optic deformation. Also, the ends of the haptics  15  push backward against the posterior capsule as indicated by arrows  46  in  FIG. 9  with increases of vitreous pressure. 
     The width of the hinges is 1.0-3.0 mm and the thickness of 0.1-0.3 mm. 
     Another feature allowing the present lens to accommodate is that the optic  14  can be deformable and may be constructed with a lower durometer than previously built into any lens. The surrounding plate  12  preferably is made of a higher, standard durometer material, similar to the eyeonics Inc. AT45 lens (which is durometer 48). The optic  14  itself is not required to contribute to the structural stability of the lens and, therefore, the optic  14  can be extremely soft. In addition to forward axial translation, the bending or deformation of the optic  14  with accommodation will induce power change. This may result in the bending of the optic to be accentuated. This feature is further enhanced by maintaining the optic very thin since a thinner optic will bend more than a thick optic for any given level of force applied. An example range of optic  14  center thicknesses is about 0.4 mm to 1.3 mm for a diopter range of 10 to 33. A typical common diopter of the optic of the present lens is 22 diopters and which has a thickness of 0.73 mm. As a comparison, the AT 45 noted earlier in a 22 diopter has a thickness of 0.88 mm, and a newer AT-45SE is 0.98 mm. 
     A 4.5 mm diameter optic  14  and with a reduced edge thickness of 0.1 to 0.2 mm for example can be provided. The index of refraction can be increased and this will accentuate this feature even further. 
     The present lens can be easily foldable with forceps or an injector. A pre-loaded system is preferable. 
     An additional feature is the incorporation of a ridge or ridges  40  on the back surface (posterior side) of the plate  12  and/or haptic arm as the case may be as seen in  FIGS. 3 and 7 . These ridges traverse the plate and completely encircle the optic around the perimeter of the lens body. There is an additional ridge central to the first ridge traversing the plate adjacent to the optic straps. The purpose of these ridges is to prevent proliferation of lens epithelial cells into the area behind the plate or optic. For plate lenses this can dramatically reduce the incidence of capsular contraction. Epithelial cells will be prevented from migrating under the plate and undergoing a fibrotic contraction. Furthermore, the square edge of the loops, plate haptics and the square edge of the optic further protect against cells migrating in from the sides of the plate. 
     While an embodiment of the present invention as 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.