Patent Publication Number: US-2011060409-A1

Title: Optics and IOLs for Inhibiting cell migration and reduce optic edge dysphotopsia

Description:
The present application claimed priority from U.S. Provisional Patent Application Ser. No. 61/239,928. This application is incorporated herein in its entirety by this specific reference thereto. 
    
    
     This invention relates to intraocular lenses (IOLs) and, more particularly, to IOL which inhibits cell migration from the eye onto an optical zone of the IOL and reduce optic edge dysphotopsia in the eye. 
     An intraocular lens is commonly used to replace the natural lens of a human eye for aphakia treatment. It is common practice to implant an IOL in a region of the eye known as the capsular bag. There are two problems with many IOLs following implantation in the capsular bag:
         (1) Reduction of image contrast caused by the cells migration to the optical zone of the IOL   (2) dysphotopsia caused by light reflecting off the peripheral edge of the IOL optic,       

     A common treatment for this condition is to use a laser to destroy the cells and a central region of the posterior capsular bag. Although this treatment is effective and is usually done when the vision diminishes to unacceptable level. There is also cost associated with the laser treatment. In addition, it also may result in the IOL positional shift in the capsular bag thus affecting IOL optical performance. 
     So-called “square-edged IOL” design with sharp transitions between the IOL edge and the surfaces seems to help in delaying the cell migration. Another benefit observed was a tight capsule shrink-wrap effect with the square-edged IOLs with the fibrotic ring, allowing minimal IOL shift. The round-edged IOLs on the other hand, tends to decenter and rotate more. This consideration is particularly important for tonic IOLs where the lens meridional orientation inside the eye is the critical factor to providing acceptable performance for cylinder correction. It is also important consideration for Accommodating IOLs which rely on the lens positional stability. 
     Thus, while square-edged IOLs are more helpful in preventing the cell migration they manifest the issue of light reflection off the optic edge surface resulting in the reports of dysphotopsia by some patients. The dysphotopsia can be an annoyance up to the point of requesting the IOL removal and replacement for other type of IOL. The round-edged IOLs on the other hand, are known to minimize edge dysphotopsia as compared with square-edged IOLs. This is due diversion of the light reflected from the rounded optic edge over the wider area of the retina thus reducing the light intensity. 
     U.S. Pat. No. 6,162,249 describes the IOLs with optic peripheral edge having a substantially continuous curved configuration relative to the central optical axis in order to maintain square-edge IOL feature to have a sharp edge at the junction between peripheral edge surface and optical surface of the IOL and, as a result, to inhibit cell migration together with the reduction of edge glare or dysphotopsia. 
     The issue with the proposed IOLs in the U.S. Pat. No. 6,162,249 is difficulty of manufacturing such an peripheral edge shape thus limiting the edge shape to certain configurations which might not be optimal for reduction in edge dysphotopsia. The common process to produce optic peripheral edge of the optic is to use milling where the endmill cuts out the lens shape from the button or cut the corresponding shape in the mold for the optic molding. To produce the optic peripheral edge shape that is not parallel to the optical axis would require a specially shaped endmill and its precise location along the vertical axis parallel to the optical axis or additional fabrication process to polish out the optic periphery edge to a desirable configuration. 
     Thus, it would be advantageous to introduce IOLs which inhibit growth of cells at the IOL placed in the capsular bag and further optimize the optic peripheral edge shape for dysphotopsia reduction and also to allow using conventional manufacturing processes. 
     SUMMARY OF THE INVENTION 
     New IOLs have been discovered that combine ease of manufacturing with an unlimited configurations of the optic peripheral edge to diverge the reflected light over the wide area of the retina. Such IOLs are effective to inhibit cell migration due to the presence of sharp discontinuity between the optical peripheral edge surface and lens anterior or posterior surface. The optic peripheral edge surface can maintain flat shape parallel to the optical axis of the optic and as such, easy to manufacture with a commonly available endmill and utilizing conventional manufacturing processes. 
     The IOLs in accordance with the present invention includes an optic having a central optical axis, an optic anterior surface, an opposing optic posterior surface and an optic peripheral edge between the optic surfaces. The optic of the IOL is adapted for placement in the capsular bag of the eye and for focusing light toward the eye&#39;s retina. The IOLs in accordance with the present invention further include at least one fixation member commonly called a haptic, and preferably two fixation members, connected to the optic for fixation the IOL in the eye. In general, the IOL may include a plate shape haptc or include the optic consisting of several lenses. 
     The optic peripheral edge of the present IOLs include an undulated or periodic segment of a substantially continuous configuration in the direction around the central optical axis of the optic, meaning in the plane perpendicular to the optical axis of the optic. A preferable embodiment includes the entire optic peripheral edge having a substantially continuous curved configuration of variable curvature i.e., undulated or periodic in the plane perpendicular to the optical axis thus maintaining the cylinder shape of the optic peripheral edge substantially around the optic. 
     The variable curvature of substantially continuous curved configuration includes radii with their optical centers either within the optic and outside the optic and also being substantially smaller the radius of the optic of equivalent dimension but circular shape of substantially constant radius. The presence of the regions of smaller radii results in broad divergence of the reflected from the optic peripheral edge light over much larger retinal area than in the circular shape optic with substantially constant radius of the flat peripheral edge. Therefore, the present IOLs lead to reduced edge dysphotopsia in the eye relative to the dysphotopsia gained with a substantially identical IOL with optic shape of substantially constant radius and peripheral edge surface of flat peripheral edge. 
     Thus, optic peripheral edge of the disclosed IOL maintains discontinues sharp corner (corner edge) between the optic peripheral edge surface and optical surface, so called square-edged shape as the prior art square-edged IOL with the optic of a substantially constant radius. In general, the flat peripheral edge between anterior and posterior surfaces of the invented IOL may be tilted from preferable parallel to central optical axis configuration to up about 45 degrees to the central optical axis. The preferable embodiment maintains discontinuous sharp corners between the optical peripheral edge and both anterior and posterior optical surfaces. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a partial cross-sectional view of an optic of a prior art IOL. 
         FIG. 2  is a partial cross-sectional view of another optic of a prior art IOL. 
         FIG. 3  is a plane view of one embodiment of IOL in accordance with the present invention superimposed over the equivalent IOL shape but with circular optic of substantially constant radius. 
         FIG. 4  is a cross-sectional view taken generally along line  4 - 4  of  FIG. 3 . 
         FIG. 5  is a plane of a segment taken from the IOL of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a partial cross-sectional view of an optic  10  of a prior art IOL which has curved optic peripheral edge  30  along the central optical axis  50  as compared with a flat optic peripheral edge  40  (dashed line) that is parallel to the optical axis  50 . The optic peripheral edge maintains sharp corner edge  35  with anterior or posterior surface  20  similar to the flat optic peripheral edge  40  to provide inhibition of cell growth. Curved optic peripheral edge  30  provides a reduction in dysphotopsia as compared with flat circular peripheral edge  40  of the optic with substantially constant radius. 
       FIG. 2  illustrates a partial cross-sectional view of an optic  100  of another prior art IOL which has more complex curved optic peripheral edge  130  along the central optical axis  150  as compared with the flat optic peripheral edge  140  that is parallel to the optical axis  150 . The optic peripheral edge also maintains sharp corner edge  135  with anterior or posterior surface  110  similar to the flat optic peripheral edge  140  to provide inhibition of cell growth. Curved optic peripheral edge  130  also provides a reduction in dysphotopsia as compared with flat circular peripheral edge  140  of the optic with substantially constant radius. 
       FIG. 3  illustrates a plane view of an embodiment of IOL  200  in accordance with the present invention. In this embodiment, the optic  205  incorporates an undulated or periodic peripheral edge  210  around the optic except at the location of the fixation members  230  and  240 . The optic  205  of optic diameter “d” is superimposed over the optic of constant radius that is half of “d” and with circular peripheral edge  220 . The optic  205  has central optical axis  260  which is also the optical axis of the optic with circular peripheral edge  220 . The optic may have an oval shape and the corresponding diameter is the average diameter of smallest and largest optic diameters. 
     In this embodiment, the optic  205  is circular shape in plan, with an undulated or periodic peripheral edge  210  and bi-convex shape with the optical axis  260 . However, this configuration is clearly illustrative as other configurations and shapes may be employed. 
     The optic  205  may be constructed of any of the commonly utilized IOL materials used for rigid optics, such as polymethylmethacrylate (PMMA), or commonly employed materials used for deformable optics, such as silicone polymeric materials, acrylic polymeric materials, hydrogel-forming polymeric materials and the like. 
     Two fixation members  230  and  240  in this embodiment are generally C or J-shaped and are connected to the optic  205 . However, this is purely illustrative of the fixation members  230  and  240  as the fixation members may be of other configurations and numbers. 
     The segment  250  of the optic  205  that includes variable radii of the peripheral edge  210  and the central optical axis  260  is referenced to in order to explain the invented IOL in more details in the following figure. 
       FIG. 4  illustrates a cross-sectional view taken generally along line  4 - 4  of  FIG. 3 . The preferred embodiment of peripheral edge  210  of the optic  205  is shown as flat and parallel to the optical axis  260  and include discontinuous sharp edges  215  and  225  between the peripheral edge surface and anterior and posterior surfaces  270  and  275 . The peripheral edge  220  of the optic of substantially constant radius of half diameter “d” shown on  FIG. 3  is also included for the reference. 
     In general, the inhibition of the cell and reduction of the edge glare per the invented IOL can be achieved with the peripheral edge being substantially flat with discontinuous sharp corner edge forming between the peripheral edge surface and only one of the anterior and posterior surfaces. The substantially flat peripheral edge surface can be tilted to the optical axis by up to about 45 degrees. 
       FIG. 5  explains the invented IOL in more details on the example of the segment  250  of  FIG. 3 . The peripheral edge  210  within the segment  250  of the optic  205  includes the regions “A” and “B” of substantially continuous curvatures which include radii “R I ” and “R O ” somewhere within the corresponding regions “A” and “B” correspondently. The central optical axis  260  and the peripheral edge  220  of substantially constant radius with the same optical axis  260  are shown on the figure. The radius “R I ” has the center of radius  280  within the optic  205  and is substantially smaller the distance between peripheral edge  220  and optical axis  260 . The radius “R O ” has the center of radius  290  outside the optic  205  and is also substantially smaller the distance between peripheral edge  220  and optical axis  260 . 
     The segment  250  of the preferred embodiment includes the regions “A” and “B” that are connected and repeated substantially over the whole peripheral edge  210  of the optic  205  in  FIG. 3 . In general, the regions can be located at substantially different parts of the optic peripheral edge and without a repetition.