Abstract:
Apparatus and methods are described, including a corrective optical film for converting a corrective single-focal lens to a multi-focal lens and/or a progressive lens. A thickness and/or a curvature of the corrective optical film is different in different regions of the corrective optical film, such that the corrective optical film is configured, upon being adhered to the single-focal lens, to change a focal length of the single-focal lens differently in different regions of the single-focal lens. Other applications are also described.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to multifocal ophthalmic lenses, progressive lenses, lens designs, eyeglasses. More specifically, the present invention relates to converting single vision lenses to multifocal or progressive lenses. 
         [0002]    Background Art 
         [0003]    Presbyopia, is usually treated with multifocal eyeglasses, progressive eyeglasses or contact lenses. Many method for creating and manufacturing of progressive lenses are known in the art, such as polishing a semi-finished lens or molding. LASIK and other types of surgery cannot prevent or remedy this natural occurrence, which gradually affects nearly everyone over age 40. The visual effects caused by Presbyopia may slowly worsen for several years, requiring new changes in lens prescription, but will stabilize by age 65 or 70. 
         [0004]    Corrective lenses are used in eyeglasses to correct Presbyopia and other disorders of accommodation. A basic solution for Presbyopia is the use of multifocal spectacle lenses. Multifocal spectacle lenses contain two or more lens powers to help you see objects at all distances. Bifocals contain two lens powers; trifocals contain three. 
         [0005]    Progressive spectacle lenses are characterized by a gradient of increasing lens power, added to the wearer&#39;s correction for the other refractive errors. The gradient starts at the wearer&#39;s distance prescription, at the top of the lens and reaches a maximum addition power, or the full reading addition, at the bottom of the lens. The addition in middle of the lens usually enables reading text on a computer screen. The length of the progressive power gradient on the lens surface depends on the design of the lens, with a final addition power between 0.75 and 3.50 diopters. The addition value prescribed depends on the level of presbyopia of the patient. 
         [0006]    The main disadvantages of multifocal eyeglasses and progressive lenses are their high cost and their need for professional adaptation. 
         [0007]    There is thus required a method and system that provides a reasonable solution for the Presbyopia problem, while keeping a very low price that enables use of progressive lenses by everyone who needs it. Such a solution usually will not require a professional adaptation. 
         [0008]    Description of the Prior Art 
         [0009]    There are many means of converting conventional eyeglasses. 
         [0010]    U.S. Pat. No. 2,511,329 describes a cover for a spectacle lens including, a thin flat sheet of tinted transparent material substantially the size and shape of a lens, and an adhesive on one side of the sheet, the sheet being weakened along a line establishing an area that can be removed at will. 
         [0011]    U.S. Pat. No. 2,759,394 describes a glare shield for a concave-convex lens, said shield comprising a thin, pre-formed, substantially non-stretchable self-supporting sheet of tinted transparent material having uniform thickness and of no greater overall plan dimensions than said lens, said sheet comprising a narrow peripheral border portion pre-formed into a predetermined concave shape to conform to the convex surface of said lens, the remaining central major portion of said sheet within the inner periphery of said border portion being curvably pre-formed to a concave curvature greater than the convex curvature of said convex lens surface, whereby said central major portion is out of contact with said convex lens surface when said border portion is in conforming contact with said convex lens surface within the periphery of said lens surface, a layer of pressure-sensitive adhesive on only the lens-engaging face of said border portion to removably adhere said sheet to said lens, and an upset portion of said border portion restricted in extent to lie within the peripheral boundaries of said sheet and pre-formed to stand upwardly out of the curved path established by the border portion sufficiently to accept a fingernail thereunder between said upset portion and said lens surface for the purpose of removing said sheet from lens, said upset portion providing by expansion latitude the exact curvature of said border portion to fit lenses of slightly differing convex outer surface curvatures. 
         [0012]    U.S. Pat. No. 3,628,854 describes a thin, fully conformable, plastic membrane which can be applied, and made to adhere with finger pressure, to spectacle lenses for quickly and impermanent changing one or more optical characteristics of the spectacle lenses. The membrane may be embossed on one of its surfaces to form a Fresnel-type lens or prism structure to introduce a deviation of the light ray, may be partially or entirely tinted to pass only certain wavelengths of light, may be diffused, or blurred uniformly or differentially, may have selective opaqued or transmitting areas or a combination thereof. 
         [0013]    U.S. Pat. No. 5,764,333 describes a method and kit for making sunshields for eyeglasses. 
         [0014]    The sunshields are flexible, transparent sheets of smooth plastic film that are retained on lenses of eyeglasses by electrostatic attraction. The sunshields are made of smooth plastic film having opposed parallel surfaces that are flat and planar except as the film may be curved to match surfaces of the lenses, and absorb some incident electro-magnetic radiation. The method includes the steps of laying eyeglasses on a sheet of writing material and tracing an outline of lenses of the eyeglasses on the sheet with a writing implement, cutting along the outlines on the sheet to obtain silhouettes of the lenses, comparing the silhouettes to the lenses in the eyeglasses to see if they match, and laying the silhouettes on a sheet of the smooth plastic film, and cutting the plastic film along the edges of the silhouettes. Also included in the invention is a carrying case for the sunshields, having a material on its interior surface which can impart an electrostatic charge to the sunshields. 
         [0015]    In U.S. Pat. No. 6,290,354, non-corrective eyewear such as sunglasses, skiing goggles and diving masks can be easily and economically made to correct eyesight with a corrective eyewear attachment that is aesthetically pleasing. The attachment may include a corrective nose piece connector and/or a rotatable lens. The rotatable lens makes it more economical to have prefabricated corrective lenses that requires a particular lens orientation such as when the corrective lens corrects for an astigmatism. 
         [0016]    In U.S. Pat. No. 7,036,929 B, an apparatus and method for applying and removing a disposable optical film to and from an eyeglass lens is described. The disposable optical film of the invention has an adhesive element on one side for the removable attachment to an eyeglass lens. The adhesive element is protected by a peel and stick backing that has indicia defining the parameters of the corrective film, thus allowing the user to trim the corrective film to the appropriate size and shape of a multiplicity of eyeglass styles without compromising the integrity of the corrective film. 
         [0017]    None of the abovementioned provides a reasonable low cost solution for the Presbyopia problem. 
       SUMMARY OF INVENTION 
       [0018]    It is therefore an object of the present invention to provide a method and system that provides a reasonable low cost solution for vision problems by applying an optical corrector sticker to a regular low cost lens. 
         [0019]    According to one embodiment of the present invention a progressive lens, made of a clear elastic material and implemented as a sticker is applied on regular single-vision spectacles. Applying the sticker may be done either during lens production process, by a sales representative or by the customer itself. 
         [0020]    According to another embodiment of the present invention an optical corrector, made of a clear elastic material and implemented as a sticker is applied on regular single-vision spectacles to correct optical vision impairments such as Astigmatism. 
     
    
     
         [0021]    In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawing, in which: 
           [0022]    [ FIG. 1 ] illustrates a regular single-vision lens to which a corrective optical film is to be applied to convert it to a progressive or a multifocal lens. 
           [0023]    [ FIG. 2 a   ] illustrates a typical cross section of one embodiment of a corrective optical film according to the present invention. 
           [0024]    [ FIG. 2 b   ] illustrates a typical cross section of another embodiment of a corrective optical film according to the present invention. 
           [0025]    [ FIG. 3 ] illustrates a corrective optical film of the present invention including a transparent adhesive backing. 
           [0026]    [ FIG. 4 a   ] illustrates a corrective optical film being protected with two films, one on each side. 
           [0027]    [ FIG. 4 b   ] illustrates simple alignment mark on one of the protection films. 
           [0028]    [ FIG. 5 a   ] illustrates a cross section of the corrective optical film attached to the outer surface of a regular single-vision lens. 
           [0029]    [ FIG. 5 b   ] illustrates a cross section of the corrective optical film attached to the inner surface of a regular single-vision lens. 
           [0030]    [ FIG. 6 a   ] illustrates measuring of the largest distance to a target where the vision is still clear without blurring. 
           [0031]    [ FIG. 6 b   ] illustrates measuring of the shortest distance to a target where the vision is still clear without blurring. 
           [0032]    [ FIG. 7 ] illustrates marking points where the pupils of each eye are located. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0033]    The following discussion describes in detail embodiments of the present invention. This should not be construed, however, as limiting the invention to those particular embodiments since practitioners skilled in the art will recognize numerous other embodiments as well. 
         [0034]      FIG. 1  shows a regular single-vision lens  100  to which a corrective optical film  120  is to be applied to convert the regular single-vision lens to a progressive or a multifocal lens. The corrective film  120  made of a clear elastic material and implemented as a sticker, is applied by using transparent adhesive material on said regular single-vision lens  100 . The corrective optical film  120  may be attached to the front surface or the rear surface of the regular single-vision lens  100 . Two or more different corrective optical films may also be attached to the front surface and the rear surface of the regular single-vision lens  100 . The single-vision lens  100  may be implemented as a transparent material without any optical corrective value. 
         [0035]      FIG. 2 a    and  FIG. 2 b    show a typical cross section of the corrective optical film  120  according to two embodiments of the present invention. The optical film  120  may have different optical powers in different regions to correct the focal length of a regular single-vision lenses differently. In one embodiment ( FIG. 2 a   ) the film  120  may have a free form. In another embodiment ( FIG. 2 b   ) the film  120  may have discrete regions  121 ,  122  and  123  of different thicknesses and different curvatures in different places. Alternatively or in addition, the film may have a graded index profile which means different refractive indices in different regions with a uniform or non-uniforms thicknesses and curvature in order to have different optical powers to change the focal lengths of the said regular single-vision lenses differently in different regions. The graded index profile may be produced according to any known method known in the industry, such as Partial polymerization by UV light, Neutron irradiation or Chemical vapor deposition. The corrective optical film  120  may be disposable or have a life time-limit, and may include other elements such as anti-glare and/or anti-scratch coating, and/or UV protective materials, and/or other additional optical functionalities as currently known in the art. 
         [0036]      FIG. 3  shows the corrective optical film  120  of the present invention including a transparent adhesive backing  130  to adhere the film to the lens to be converted to a progressive or multifocal lens. The adhesive backing may be a permanent or a peel-off adhesive backing, a self-sticking backing with a spray-on mist or any other suitable backing with a spray-on mist or any other suitable means to effectively adhere the film to the said lens. Furthermore, in order that the adhesive side doesn&#39;t prematurely stick on the sunglasses, a spray of water can be applied in order to position the film before it is in place. 
         [0037]      FIG. 4 a    and  FIG. 4 b    describe the corrective optical film  120  of the present invention when being protected with two films  200  and  210 , one on each side. Protection film  200  protects the adhesive substance  130  and is removed just before applying the corrective optical film  120  to the said single-vision lens. Protection film  210  protects the outer side of the corrective optical film  120  and is usually removed after applying the corrective optical film  120  to the said single-vision lens in a similar process which is commonly used to apply anti-scratch screen protector for a cellular phone. On the protection film  210  there may be alignment mark  220  that its purpose is to accommodate the corrective optical film  120  to the right location on the lens to be corrected. Other marks may indicate areas which should not be cut, to prevent damage to the optical areas of the corrective optical film  120 . In case protective film is not used, such erasable marks will appear directly on the corrective optical film  120  itself and will be erased after applying the corrective optical film  120  to the eyeglasses lens  100 . 
         [0038]      FIG. 5 a    and  FIG. 5 b    show a cross section of the corrective optical film  120  attached to the regular single-vision lens  100  to be converted to a progressive or a multifocal lens. In one embodiment according to the present invention ( FIG. 5 a   ) the corrective optical film  120  is attached to the outer side of the regular single-vision lens  100  (far from the patient&#39;s eye). In another embodiment according to the present invention ( FIG. 5 b   ) the corrective optical film  120  is attached to the inner side of the regular single-vision lens  100  (between the patient&#39;s eye and the lens). The single-vision lens  100  must be at a minimal size to enable different optical regions in a multifocal lens, and the film  120  will usually be larger than the single-vision lens  100 . In such case, the film  120  is cut to accommodate the size and shape of the lens on which it is to be installed. The film  120  may be cut before or after applying it to the lens. In another embodiments of the present invention, the film  120  may come in pre-defines sizes adapted for specific common models and styles of eyeglasses, and therefore the need to cut it will be eliminated. 
         [0039]      FIGS. 6 a  and 6 b    show a method for accommodating the proper corrective optical films to two single-vision lenses  300  and  320  of eyeglasses  350  in order to convert said two single-vision lenses to progressive or multifocal lenses. The customer  250  who wears said eyeglasses  350  with single-vision lenses has to do two examinations. One examination is to measure the largest distance  410  to the target  400  that he still has clear vision without blurring ( FIG. 6 a   ). The second examination is to measure the smallest distance  420  to the target  400  that he still has clear vision without blurring ( FIG. 6 b   ). These two examinations have to be done for each eye while wearing the eyeglasses. From these two sets of distances  410  and  420  the proper corrective optical films for each eye are chosen. 
         [0040]      FIG. 7  shows a method for matching the corrective optical films to the proper location on each of the single-vision lenses to be converted to progressive or multifocal lenses. The customer  250  who wears said eyeglasses  350  with said single-vision lenses to be converted, has to look with both eyes to a single point target  400  located at known distance. The customer itself or a sales representative should mark with an erasable marker on each lens of the eyeglasses a point  450  and  460  where each pupil of each eye is located. When the corrective film is applied to each lens to be converted, this mark is matched to the alignment mark  220  on the protection film  210  ( FIG. 4 a    and  FIG. 4 b   ). When the corrective film is applied to the rear surface of the lens the point  450  is marked on the front surface of the lens and vice versa. After completing the alignment, all marks required for the alignment may be erased. When using protective film  210  on the outer side of the corrective optical film, the removal of this protective film will also remove the alignment marks and leave the corrective film clear of any marks.