Abstract:
A compound micro lens having a multiplicity of micro-lenses on a common substrate, with the micro-lenses having a multiplicity of focal lengths. Having a multiplicity of focal lengths allows the compound micro lens to be used in cataract surgery to replace human eye lens and still allow the patient to focus at different depths without the need for multiple pairs of glasses or other aids.

Description:
CROSS REFERENCE TO APPLICATIONS 
       [0001]    This application is related to, and claims priority from, U.S. Provisional Patent application No. 61/026,293 filed on Feb. 5, 2008, by R. Battis et al. titled “Compound Micro Lens Implant”, the contents of which are hereby incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to ophthalmic lenses, and more particularly, to multi-focal, compound micro-lens for replacement of human eye lenses and cornea. 
       BACKGROUND ART 
       [0003]    According to the World Health Organization, age-related cataracts are responsible for 48% of world blindness, which represents about 18 million people world wide. Cataracts cause the lens of the eye to become opaque. 
         [0004]      FIG. 1  is a schematic representation of a human eye  10 . The a human eye  10  has a lens  12 , a cornea  14 , an iris  16 , and a retina  22 . When functioning normally, light is focused by the cornea  14  and the lens  12  onto the retina  22  at the back of the eye. The information is then transmitted to the brain via the optic nerve  26 . Although the cornea  14  supplies about two-thirds of the focal power of the a human eye  10 , it has a fixed focus. The lens  12  is flexible and its shape can be changed by muscles  18  to provide variable focus for the eye. 
         [0005]    The conventional surgery for cataract is to replace the lens  12  with a fixed gain synthetic lens. Although this restores the patients sight, it limits their ability to focus at different depths without the aid of glasses or contact lenses. 
         [0006]    A synthetic lens that could be used to replace lenses made inoperable by cataracts and would allow the patient to focus at different distances is, therefore, a highly desirable device. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is a compound micro lens that has a multiplicity of focal lengths and may therefore be used in cataract surgery to replace human eye lens and still allow the patient to focus at different depths without the need for multiple pairs of glasses. 
         [0008]    Technical Problem 
         [0009]    The technical problem addressed by the present invention includes the problem of how to provide a multiplicity of focal lengths with a solid lens. 
         [0010]    Solution to Problem 
         [0011]    The present invention solves the problem by providing a multiplicity of micro-lenses on a common substrate, with the micro-lenses having a multiplicity of focal lengths. 
       ADVANTAGEOUS EFFECTS OF INVENTION 
       [0012]    Advantages of the invention include, but are not limited to, the ability to use a single, solid lens to provide a multiplicity of focal lengths. 
         [0013]    These and other features of the invention will be more fully understood by references to the following drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]      FIG. 1  shows a schematic representation of a human eye. 
           [0015]      FIG. 2A  shows a plan view of a compound micro lens of the present invention. 
           [0016]      FIG. 2B  shows a sectional view of a compound micro lens of the present invention. 
           [0017]      FIG. 3  shows a schematic view of the functioning of a three focal length compound micro lens of the present invention. 
           [0018]      FIG. 4  that shows a compound micro lens have hexagonally shaped micro lenses. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0019]    Embodiments of the present invention will now be described in detail by reference to the accompanying drawings in which, as far as possible, like elements are designated by like numbers. 
         [0020]    Although every reasonable attempt is made in the accompanying drawings to represent the various elements of the embodiments in relative scale, it is not always possible to do so with the limitations of two-dimensional paper. Accordingly, in order to properly represent the relationships of various features among each other in the depicted embodiments and to properly demonstrate the invention in a reasonably simplified fashion, it is necessary at times to deviate from absolute scale in the attached drawings. However, one of ordinary skill in the art would fully appreciate and acknowledge any such scale deviations as not limiting the enablement of the disclosed embodiments. 
         [0021]      FIG. 2A  shows a plan view of a compound micro lens  30  of the present invention. The compound micro lens  30  may have a substrate  32  on which there are a large number of micro lenses. The micro lenses may have a variety of focal lengths including, but not limited to, a short focal length micro lens  34 , a medium focal length micro lens  36  and a long focal length micro lens  38 . The various focal length lenses may for instance, but are not limited to, be arranged randomly, in grid patterns, or in circular patterns as shown in  FIG. 2A . The compound micro lens  30  may also have side fixture elements  40  to hold them in place. 
         [0022]      FIG. 2B  show as sectional view of a compound micro lens of the present invention. The micro lens surface  42  may be covered by a cover material  44 . The cover material  44  may have a cover material surface  46  that may match the micro lens surface  42  or may differ from the micro lens surface  42  in order to provide additional focal power. The cover material  44  may have a refractive index that matches the refractive index of the substrate  32  and micro lenses, or it may have a different refractive index to provide additional focal power. 
         [0023]      FIG. 3  shows a schematic view of the functioning of a three focal length compound micro lens  30  of the present invention. The short focal length micro lenses  34  all focus a near by object  41  onto the retina  22 . The medium focal length micro lenses  36  all focus medium distance objects  42  onto the retina  22 . The long focal length micro lenses  38  all focus distant objects  44  on to the retina  22 . In  FIG. 2 , the short focal length micro lens  34  and medium focal length micro lens  36  are shown to focus to a point centered on the optic axis  46  of the eye, while the long focal length micro lens  38  focuses to an off axis point  48 . One of ordinary skill in the optical arts will realize that all lenses could focus to the point centered on the optic axis  46 , or all could focus to the off axis point  48 , or some combination thereof. 
         [0024]    For instance the short focal length micro lens  34  may be selected to enable a patent to read, while said long focal length micro lens  38  may be selected to enable a patent to drive a car. 
       EXAMPLES  
     Example 1 
       [0025]    Example 1 is illustrated in, for instance,  FIG. 4  that shows a compound micro lens have hexagonally shaped micro lenses. The individual micro lenses may, for instance, have a range of different shapes, including, but not limited to, circles, hexagons, polygons, partial circles, ellipses or other geometric shapes. The layout pattern, or centroids of the mico lenses may include, but are not limited to, nested rings, grid patterns, diamond patterns, random patterns or some combination thereof. The number of micro lenses in one compound lens may be as few as twenty-five or as many as several hundred, depending on the size of the micro lenses that may vary from a micron in diameter to several hundred microns in diameter. 
         [0026]    The micro lens elements may be designed as negative lenses, positive lenses or some combination thereof. 
         [0027]    Although the invention has been described in language specific to structural features and/or methodological acts, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the claimed invention. Modifications may readily be devised by those ordinarily skilled in the art without departing from the spirit or scope of the present invention. 
       INDUSTRIAL APPLICABILITY 
       [0028]    In the field of ophthalmology there is significant interest in multi focal solid lens such as the compound micro lens of the present invention, particularly for lens replacement in cataract surgery. Such lenses would be of considerable utility for cornea replacement and in the field of contact lenses.