lenses from the polymer forming composition employing the spin casting technique in accordance with this technique the dye containing polymer forming composition is introduced into a mold having a cylindrical wall and an exposed concave bottom surface and the mold is caused to rotate about its vertical axis at a rotational speed and under polymerization conditions sufficient to create a centrifugal force which causes a radially outward displacement of the contents of the mold by maintaining the rotating mold under predetermined conditions the outwardly displaced polymerizable material is caused to polymerize to a solid polymeric contact lens the resulting lens is characterized by a convex optical surface which corresponds to the concave surface of the mold and a concave optical surface whose geometric configuration has been precisely defined to a significant degree by the centrifugal force s employed during the polymerization cycle in one type of spin casting procedure a plurality of individual molds each containing a precisely measured quantity of dye containing polymer forming composition including a photoinitiator such as any of those previously mentioned is arranged in a vertically disposed rotatable polymerization tube adapted to receive the molds at its upper end as the molds which are seated one on top of the other move downwardly through the tube due to their own weight they pass while spinning through a zone of irradiation e g ultraviolet light and emerge from the bottom of the tube with the lens in each mold fully formed following irradiation the lenses within their molds can be heated if necessary or desired to complete the polymerization suitable apparatus and techniques for practicing this type of spin casting operation.