Importance

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Abstract

A fast, relatively inexpensive and simple method is disclosed for producing a finished plastic multifocal or progressive lens from a preformed lens which has a predetermined lens correction (i.e., curvature or prescription) at its optical center. The method comprises providing a mold; providing an optical quality resin composition; providing a preformed plastic lens contacting the mold such that the surfaces of the preformed lens and the mold form a cavity enclosing the resin composition; and curing the resin composition. The cavity formed by the preformed lens and the mold is shaped, among other purposes, (1) to correspond to the desired change in curvature, and (2) to ensure that the lens correction at the optical center of the resulting lens is substantially the same (preferably the same) as the predetermined lens correction at the optical center of the preformed lens. The preformed lens may also be cast with a thin non-prescription layer which acts as a carrier for the multifocal or progressive region of the finished lens. The methods disclosed allow casting of lenses without employing expensive conventional optical gaskets. The methods also allow for simpler relocation of the optical center to the proper position with respect to the multifocal or progressive prescription, preferably without using conventional optical gaskets or optical center movers.

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First Claim