fabrication of contact lenses whereby the yield of lenses removed from plastic casting molds is significantly increased . in fabricating contact lenses where a lens is initially formed in a plastic casting mold , the mold is compressed to a degree sufficient to initiate permanent deformation of the mold material , in progressive steps , incrementally decreasing in diameter from a starting diameter substantially larger than the diameter of the molded lens , until the lens self - detaches from the mold .