Methods of tinting Soflens contact lenses

Different dyes were used to tint Soflens contact lenses. The light transmission of each lens was measured before and after tinting and after asepticizing it in fresh saline from 1 to 15 times. Crystal violet was found to be the dye most stably retained within the lens after saline asepticizing. By asepticizing hydrophilic lenses in solutions of food coloring, we found that the amount of dye retained by a lens was not cumulative and the transmittance was maintained at approximately the original value. Tests of these tinted lenses for toxicity to animals or human subjects were not performed, nor did we ascertain whether these dyes affect the durability or hydrophilic and wetting properties of these lenses.