| abstract |
An improved method is disclosed of imparting a tint or color to a soft, hydrogel contact lens by uniformly dispersing a dye throughout the lens. The dye is composed of a water-soluble compound essentially free of ethylenic unsaturation. A homogeneous solution of the dye in a hydrophilic monomer is prepared, the solution is subjected to polymerization conditions to yield a hydrophilic polymer from which the lens is formed, and the dye dispersed within the polymer is bonded to the polymer by contact with aqueous base prior to final hydration. The finished lens does not require soaking in an aqueous solution of the dye to impart the desired tint or color to the lens. Additionally, the dye uniformly dispersed throughout the lens according to the improved method does not leach out of the lens or migrate within the lens. |