Patent Publication Number: US-2003223035-A1

Title: Colored contact lens and method for manufacturing the same

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to the field of a contact lens and, more particularly, to a colored contact lens having iris-colored part onto the lens core, and a method for manufacturing thereof.  
       [0003] 2. Description of the Relevant Art  
       [0004] Generally, many people desire to have beautiful eyes and more recently people desire more beautiful and natural eye colors. Every race has its peculiar iris color, which makes each face look different. Some people want to possess a unique eye color which is different from their natural eye color. However, cosmetics or other accessories are not satisfactory to them.  
       [0005] To satisfy this desire, there is provided a colored contact lens, which is made by coloring the portion of a contact lens which covers the iris. This colored contact lens may serve two purposes; improving eyesight and enhancing appearance at the same time.  
       [0006] Until now, many kinds of colored contact lenses have been developed and used by many manufacturers all over the world.  
       [0007] At first, as shown in FIG. 1, an opaque colored soft contact lens is developed from Titomus Eurocon Co. in Germany. To make this lens, the technique provides a lower lens  3  by polymerizing HEMA (2-Hydroxyethylmethacrylate) and then forms an iris-colored part  5  by individually and manually painting a desired iris color with an opaque dye or pigment on the lower lens  3 .  
       [0008] Then, a transparent upper contact lens  7  made of HEMA is bonded to the lower lens  3  having the iris-colored part  5  to make the colored contact lens  1 .  
       [0009] However, since the iris-colored part  5  is painted on the lower lens  3  by hand, a pair of lenses may have different colors due to a lack of reproduction. Additionally, since two lenses are put together, they are thicker, and thus uncomfortable to wear.  
       [0010] There is also proposed a coloring technique for an opaque colored soft contact lens from Wesley Jackson Co. in U.S. As shown in FIG. 2, this technique suggests a method of polymerizing HEMA to form a lens  13  and then forming a iris-colored part by drawing lines with innumerable dots on the lens  13 , thus making a colored contact lens  11 .  
       [0011] In this technique, the iris-colored part  15  is directly formed on a surface of the lens  13 . Though attractive, such a configuration may cause friction between the inner side of an eyelid and the iris-colored part of the contact lens. Thus, this kind of conventional lens cannot be used for a long period of time because of the possibility of conjunctivitis or absorption of waste matter, such as proteins or lipids, around the iris-colored part.  
       [0012] There is also developed a colored soft lens technique by Sereko Co. in England as shown in FIG. 3. This technique first provides a mold, and then forms a lens  23  onto the mold, in which HEMA monomer is polymerized and forms a lens having an iris-colored part  25  where opaque dyes mixed with HEMA monomer are printed, and then cut the lens  23  to make a colored soft lens  21 .  
       [0013] Although this method makes mass production possible since the mold is used to make the lens  23 , this technique has a problem in that it causes discomfort to the wearer of the contact lens and even causes keratitis as the iris-colored part on the lower side of the lens rubs a cornea when blinking.  
       SUMMARY OF THE INVENTION  
       [0014] The present invention is designed to overcome the above-mentioned problems of the colored contact lens, and an object of the present invention is to provide a colored contact lens which is comfortable and looks natural when wearing. Another object of the present invention is to provide a colored contact lens and a method for manufacturing thereof, which enables mass production with a lower cost.  
       [0015] In order to accomplish the above object, the present invention provides a colored contact lens comprising: a lens body having a cut portion and an optical portion, the cut portion formed by cutting off an upper surface of the lens body and the optical portion being upwardly protruded; an iris-colored part formed on the cut portion; and a lens cover formed by supplying a monomer and polymerizing on the upper surface of the lens body, whereby the iris-colored part is positioned on a lens core.  
       [0016] In another aspect of the present invention, there is provided a method for manufacturing a colored contact lens, the method comprising the steps of: providing a lens body by supplying the first lens material onto a lower mold and molding the first lens material with an upper mold; forming an optical portion and a cut portion by cutting off an upper surface of the lens body, the optical portion being upwardly protruded; forming an iris-colored part having an iris shape with a color on the cut portion; and forming a lens cover by supplying the second lens material onto the lens body and polymerizing the second lens material with a surface of the lens body.  
       [0017] The method may further comprise the step of cutting off an upper surface of the lens cover after forming the lens cover.  
       [0018] Preferably, the lower and upper molds are made of a material selected from the group consisting of polycarbonate, polybutyleneterephthalate and a mixture thereof.  
       [0019] The method may also further comprise the step of printing a transparent color on a surface of the optical portion.  
       [0020] Preferably, the iris-colored part is formed by multiple printing in dot pattern.  
       [0021] In addition, the first and second lens materials are preferably selected from the group consisting of HEMA(2-Hydroxyethylmethacrylate), HEMA+NVP (N-Vinyl-2-Pyrrolidone) and a mixture thereof.  
       [0022] Furthermore, the iris-colored part is preferably formed by a mixture of colorant, TiO 2 , and at least one of HEMA and HEMA+NVP.  
       [0023] In still another aspect of the present invention, there is also provided a method of manufacturing a colored contact lens, the method comprising the steps of: providing a lens body by supplying a lens material onto a lower mold and molding the lens material with an upper mold; forming a cut portion by cutting off an upper surface of the lens body; forming an iris-colored part having an iris shape with a color on the cut portion; and supplying the lens material onto a surface of the lens body and polymerizing the lens material with the surface of the lens body.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0024] These and other features, aspects, and advantages of preferred embodiments of the present invention will be more fully described in the following detailed description, taken with the accompanying drawings. In the drawings:  
     [0025]FIG. 1 is a sectional view showing an example of a colored contact lens according to the prior art;  
     [0026]FIG. 2 is a sectional view showing another example of a colored contact lens according to the prior art;  
     [0027]FIG. 3 is a sectional view showing still another example of a colored contact lens according to the prior art;  
     [0028]FIGS. 4 a  to  4   g  subsequently show a method of manufacturing a colored contact lens according to a first embodiment of the present invention;  
     [0029]FIG. 5 shows the colored contact lens manufactured by the first embodiment of the present invention; and  
     [0030]FIGS. 6 a  to  6   f  subsequently show a method of manufacturing a colored contact lens according to a second embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0031] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.  
     [0032] Firstly, a colored contact lens according to the first embodiment includes a lens body  60  and a lens cover  80 , wherebetween an iris-colored part  66  is formed at a position corresponding to the iris.  
     [0033] The lens body is formed by injecting and polymerizing monomer. The iris-colored part  66  can be printed with a predetermined color on the lens body  60 . The lens cover  80  is formed on the lens body having the iris-colored part  66  by injection and polymerizing monomer which is identical to or different from that of the lens body  60 .  
     [0034] The colored contact lens also includes a cut portion  62  and a optical portion (a), the cut portion  62  formed by cutting off an upper surface of the lens body  60  and the optical portion (a), where light enters, having a protrusion  64  upwardly protruded from the cut portion  62 . The iris-colored part  66  is printed on the cut portion  62  except the optical portion.  
     [0035] According to the present invention, the lens cover  80  is polymerized on the lens body  60  after the iris-colored part  66  is printed on the cut portion  62 , whereby the iris-colored part  66  is positioned not on a lens surface but on a lens core.  
     [0036] To make the colored contact lens according to the first embodiment, as shown in FIGS. 4 a  and  4   b,  a first lens material  50  is injected onto a lower mold  30  to shape a contact lens. The first lens material  50  is then pressed with a pressing surface  42  of an upper mold  40  to form the lens body  60 .  
     [0037] The upper and lower molds  30 ,  40  can be made of polycarbonate or polybutyleneterephthalate.  
     [0038] As shown in FIG. 4 c,  there is provided a protrusion  64  by forming the cut portion  62 , which is made by cutting off the upper surface of the lens body except for the optical portion (a) on the lens body  60  so that the optical portion (a) is protruded to a certain height.  
     [0039] The optical portion (a) refers to the circular area corresponding to the pupil in the center of an iris. A transparent color can be printed upon the optical portion (a) of the protrusion  64 .  
     [0040] Then, as shown in FIG. 4 d,  an iris-colored part  66 , having an iris shape, is formed on the cut portion  62  with a predetermined color.  
     [0041] At this time, several colors may be printed multiple times in an iris shape on the iris-colored part  66  so that the contact lens may have diverse, precise and clear colors.  
     [0042] In addition, the iris-colored part  66  may represent a line by connecting innumerable dots in a dot pattern.  
     [0043] The predetermined color for the iris-colored part  66  is preferably made of a mixture of colorant, TiO 2 , and HEMA or HEMA+NVP.  
     [0044] Such an opaque pattern of the iris-colored part  66  may be changed as desired, and may have mono-color or multiple opaque colors. The colorant should preferably be one officially adopted by the FDA in America. The following colorants are available.  
                       TABLE 1                       Colorant   C.I No   Cas No                  D&amp;C Green No. 6: 21CFR 74.3206   61565   128-80-3       D&amp;C Yellow No .10: 21CFR 74.37190   47005   8004-92-0       [Phthalocyaninato(2-)]copper: 21CFR 74.3045   74160   147-14-8       Carbazole violet: 21CFR 73.3107   51319   6358-30-1       Sudan III: 21CFR 74.3230   26100   85-86-9                                          
 
     [0045] As is shown in FIGS. 4 e  and  4   f,  a second lens material  70  is supplied on the lens body  60 , on which the iris-colored part  66  is formed. Pressing the second lens material  70  is then performed with the upper mold to form the lens cover  80 .  
     [0046] The first and second lens materials  50 ,  70  are selected respectively from the group consisting of HEMA (2-Hydroxyethylmethacrylate), HEMA+NVP (N-Vinyl-2-Pyrrolidone) or their mixture.  
     [0047] As shown in FIG. 4 g,  an upper surface of the lens cover  80  can then be cut to produce a smooth surface. As it is retrieved from the lower mold  30 , the colored contact lens (A) of the present invention is completed.  
     [0048] Referring to FIG. 5 showing the surface of the lens cover  80 , it clearly shows the iris-colored part  66 .  
     [0049] A method for manufacturing a colored contact lens according to the second embodiment of the present invention is described.  
     [0050] Referring to FIGS. 6 a  and  6   b,  a lens material  150  is injected onto a lower mold  130 . The lens material  150  is then pressed with a pressing surface  142  of an upper mold  140  to form the lens body  160 .  
     [0051] As shown in FIG. 6 c,  a cut portion  162  is formed by cutting off the upper surface of the lens body  160 .  
     [0052] As shown in FIG. 6 d,  an iris-colored part  166  of an iris shape with a predetermined color is formed on the cut portion  162 .  
     [0053] As shown in FIG. 6 e,  the lens material  150  is then supplied onto the lens body  160  on which the iris-colored part  166  is formed. The lens material  150  is polymerized on the surface of the lens body  160 .  
     [0054] At this time, the lens material  150  and the predetermined color for the iris-colored part are made of substantially identical to those of the first embodiment.  
     [0055] The present invention has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.