Novartis AG
Method for manufacturing toric contact lenses

Abstract:

A method of manufacturing of an astigmatic contact lens having a toric portion and a ballast portion such that said ballast portion causes the toric portion of the contact lens to properly orient in the eye of the wearer. The toric lenses are manufactured by an effective process control method for cylinder axis angle in toric lens production by modifying the target cylinder angle for mold rotation by eliminating the accumulative cylinder axis error from all previous steps including tool making, tool assembly, and molding. The amount modifying the target angle is determined by accurately determine the true cylinder axis on the corresponding mold by using a high-resolution interferometer, such as FISBA FS10M or equivalent models from Trioptics .mu.Shape.RTM. vertical series.