Abstract: A polymeric bifocal lens production process including the steps of selecting a single vision lens or lens blank with a convex surface, and a bifocal mould with a smaller radius of curvature; toughening the convex surface of the lens or lens blank; assembling the mould and lens or lens blank with catalysed monomer between the mould and the lens or lens blank; holding the lens or lens blank and the mould in position relative to one another so that the lens or lens blank contacts the mould; curing the monomer; removing the mould and post-curing to relieve stress in the bifocal lens and to allow the cured monomer to shrink in a controlled manner thereby causing a power decrease in the bifocal segment, whereby the cured monomer cast on to the lens or lens blank is of higher refractive index than the lens or lens blank.

Abstract: A gasket assembly for casting optical lenses includes a first gasket member having a cylindrical opening therethrough and an annular flange extending radially inwardly in the cylindrical opening. One surface of the flange is adapted to receive a casting lens die, and may be disposed in a plane not perpendicular to the axis of the cylindrical opening. A second gasket member is adapted to be received in the first gasket member, and includes an inwardly extending annular flange having one surface adapted to mate with the flange of the first gasket member. The other side of the annular flange of the second gasket member includes a shaped surface adapted to receive a lens casting die having the capability of conferring on the cast lens any combination of power and cylinder characteristics, the shaped surface being configured to mate and seal with the peripheral area of the compound surface of the die.