Inventors:
Alan D. Maki - Chaska MN
Jeffrey L. VerMurlen - Brooklyn Park MN
David C. Olund - Stanchield MN
Assignee:
Vision-Ease Lens, Inc. - Ramsey MN
International Classification:
G02C 702
US Classification:
351159, 351168, 351161, 351177, 264 25
Abstract:
Multifocal ophthalmic lenses may be manufactured by either injection molding and casting methodologies. The use of two opposed tools (mold faces) with relatively centered faces, but with significantly differing diameters can be used to provide multifocal ophthalmic lenses. The process is surprisingly capable of providing multifocal lenses with good control of the thickness of the lenses, with relatively thin center thicknesses (e. g. , less than 4. 7 mm, or less than 3. 5 mm) and relatively thin edge thicknesses (e. g. , 0. 5 to 2. 5 or to 2. 0 mm). The tool faces (the molds for the front and rear surfaces) may be readily replaced within the mold to enable manufacture of a wide range of lens prescriptions with minimum down time.