Colored contact lenses and method of making same

Details Colored contact lenses and method of making same Colored contact lenses and method of making same

2000-09-08

2002-01-08

Vargot, Mathieu D. (Department: 1732)

Plastic and nonmetallic article shaping or treating: processes

Optical article shaping or treating

Composite or multiple layer

C264S002600

Reexamination Certificate

active

06337040

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to contact lenses having a color pattern simulating the natural color structure of the human iris. The invention also relates to methods of producing such lenses.
BACKGROUND AND PRIOR ART
It is often desired that contact lenses be colored or tinted for various purposes. The tinting may be useful for identification purposes and also to protect the user from bright light. Lenses may also be tinted for cosmetic purposes, not only to enhance the natural coloring of the eyes, but sometimes to conceal disfigurements.
The coloring of materials of this nature has been a demanding assignment. The colorants must be incorporated without interfering with the optical properties of the final product. They must resist leaching out on storage and autoclaving, and must not undergo decomposition in the presence of reagents used in daily cleaning and sterilization of the lens material. They must not fade upon prolonged exposure to light, and they must be non-toxic and physiologically inert, as well as mechanically non-irritating. From a commercial standpoint, it is necessary that the colorants be applied in a process which is not so complex or time consuming or labor intensive as to be impractical.
A special problem arises from the fact that the natural appearance of the human iris is not a simple solid color, but consists of a patterned structure involving many shapes and colors. Therefore, colored lenses having merely a solid color in the iris area have the disadvantage of producing an unnatural appearance when fitted in the eye.
U.S. Pat. No. 4,640,805 discloses a method in which color is applied to the lens during the manufacturing process, and spin casting techniques are used for accurately limiting the application of colorant to the iris area. However, the coloring material is dissolved into the monomer material as a solid color, without any attempt to match the natural color pattern of the human iris. U.S. Pat. No. 4,252,431 discloses a method of ensuring color only in the iris area and not in the white periphery, by separately preparing and assembling a tinted central core and a clear outer lens element. However, here again, the tinted central core is provided with a solid color, without the simulation of the natural iris pattern.
In U.S. Pat. Nos. 4,582,402 and 4,704,017, water-insoluble opaque pigment particles are deposited on the lens surface in the iris area, in a pattern designed to simulate the natural structure of the iris, using offset pad printing techniques. However, in the process disclosed in these patents, the lens must first by produced, and then, in an added manufacturing segment, the pigment pattern is prepared and transferred to the surface of the previously prepared lens. Following this, the lens is subjected to further treatment to fix the pigment to the surface of the lens and render it resistant to leaching, abrasion, fading, and the like. U.S. Pat. No. 4,668,240 also discloses a process in which a coloring substance and a binding agent are printed in an iris pattern on the surface of a contact lens. Here again, however, the lens must be first produced, and the printing is accomplished in a series of additional steps in a later manufacturing segment.
It is an object of the present invention to provide a process in which a single-or multi-colored pattern is printed and fixed in the lens during the actual manufacture of the lens itself, thus enabling significant reductions in manufacturing time as well as costs of labor and materials.
It is another object of the invention to provide an optical lens in which the printed pattern becomes a part of, and is protected by the lens matrix, adjacent the surface of the lens.
It is a further object of the invention to provide an optical lens in which the printed pattern exhibits superior resistance to ocular fluids, bleaches, hydrogen peroxide, boiling water and other chemicals, such as alcohol, acetone and freon, which come in contact with the lens during manufacturing finishing steps or daily maintenance of the lens.
A still further object of the invention is to provide a optical lens in which an active material other than a coloring material (e.g., a therapeutic agent) is fixed in the lens during the actual manufacture of the lens itself, using the special procedures disclosed hereinafter.
Other objects and advantages will be apparent from the following description and examples.
SUMMARY OF THE INVENTION
This invention is based on the surprising discovery that a highly effective colored printed pattern, such as an iris pattern, can be applied to an optical lens in the course of producing the lens itself. It has been found that, by using a specially prepared color dispersion to imprint a pattern on one or both surfaces of the lens casting mold and then proceeding with the usual steps of filling the mold with monomer, polymerizing, and finishing, it is possible to produce a optical lens having a high quality pattern embedded in the lens matrix adjacent its surface. Applying the pattern in this manner not only improves the preciseness and reproductibility of the manufacturing process but also enhances the quality of the end product. Further, applying the printed pattern to the casting mold permits the coloring step to be incorporated as an integral part of the manufacturing process, rather than reserving it as a separate, subsequent manufacturing operation. The discovery therefore significantly reduces repetitive handling of the plastic lens materials and enables efficient automation of the complete operation. The coloring agents which have been found useful in the foregoing are insoluble pigments or dyes which are dispersed in a resin system.
The invention therefore may be described in general terms as a method of producing a colored contact lens comprising the steps of selecting a coloring material which is insoluble in the monomer material to be used in the lens, dispersing the coloring material in a resin system which is compatible with the monomer material, using the resulting dispersion to imprint a pattern on one or more surfaces of a casting mold in contact with the imprinted surface or surfaces, and polymerizing the liquid to produce a lens blank having a colored pattern impregnated in said blank, adjacent one or both optical surfaces thereof.
A preferred embodiment of the invention is a method of producing a colored soft contact lens comprising the steps of providing a resin system by dissolving from about 10 to 30% by weight of a thermoplastic resin, such as polyvinyl alcohol, in about 90 to 70% by weight of a solvent, such as butanol; dispersing in the resulting solution from about 1 to 80% by weight of insoluble pigments, such as phthalocyanine blue, phthalocyanine green, titanium dioxide, iron oxides, or mixtures thereof; using the resulting dispersion to imprint an iris pattern on one or both surfaces of a casting mold; introducing a hydrogel-producing monomer, such as hydroxy ethyl methacrylate monomer, in the mold in contact with the imprinted mold surface or surfaces; and polymerizing the monomer to produce a lens blank having a colored iris pattern impregnated in the blank, adjacent one or both optical surfaces thereof.
Another embodiment of the invention comprises marking both sides of a lens blank with matching white and colored dots or rings, such that the white dot with the white sclera on the outer convex side of the lens, while the colored dot or indicia shows on the inner or concave side of the lens, to assist the wearer in determining whether the flexible lens has turned inside out (i.e., whether the lens has the proper vertiness).
The invention also comprises a new product-namely, an optical lens having an active material encapsulated in resin capsules impregnated in the lens, adjacent one or both optical surfaces thereof. For the purposes of this specification, the term “active material” includes (1) insoluble materials that provide color in the lens or a means of controlling radiation, such as UV radiation or (2) soluble therapeutic agents.
DETAILED DESC

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