Basecurve mold designs to maintain hema ring/basecurve adhesion

摘要

Designs for basecurves are disclosed which are designed to promote adhesion of an excess polymer HEMA ring to the basecurve during a demolding operation such that the excess polymer HEMA ring is removed along with the basecurve during the demolding operation. The basecurve mold designs promote and maintain adhesion of an excess polymer HEMA ring to the basecurve in a process for molding cast contact lenses in mold assemblies, each comprising a frontcurve and a spaced basecurve, and wherein a molded lens is formed therebetween. In one embodiment an annular area of the basecurve mold adjacent to the excess polymer HEMA ring is formed with laser machining marks therein, formed by laser machining a corresponding annular area in a master mold used to cast the basecurve molds. In a second embodiment the annular area of the basecurve mold is formed with electric discharge machine marks therein, formed by electric discharge machining a corresponding annular area in a master mold used to cast the basecurve molds. In further embodiments, the annular area of the basecurve mold can be formed with projecting teeth which project into the excess polymer HEMA ring, or with an annular step which contacts the excess polymer HEMA ring. Moreover, the annular step can include a plurality of projecting teeth therearound, or can define a spoked design or an edgecut design.