Colored soft contact lens and method and apparatus for forming

Abstract From the Canadian patent

A method for forming a colored image in a limited area of a vision-corrective soft contact lens. In one method the lens is soaked in a diazonium salt and then exposed to actinic light through a mask which transmits light only to the non-image area of the lens. Then the unexposed, image area is developed by contact with an azo coupler. In a second method, the diazonium salt is soaked in a gel relief of the desired image configuration and contacted with the lens. The image is developed by soaking in the azo coupler. In a third method, the diazonium salt azo coupler, and a coupling inhibitor (a pH reducing agent) are premixed and applied by the gel relief. The image is then developed by …