Importance

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Abstract

A fast, relatively inexpensive and simple method for producing a finished plastic aspheric 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 includes providing a mold; providing an optical photoactivated resin composition; providing a preformed plastic lens; contacting the preformed lens with 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 upon application of heat and ultraviolet radiation. The cavity formed by the preformed lens and the mold is shaped to correspond to the desired change in curvature of the mold surface. 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. This allows casting of lenses without employing either expensive conventional optical gaskets or back molds. The methods also allow for simpler relocation of the optical center to the proper position with respect to the multifocal or progressive prescription, without using conventional optical gaskets.

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First Claim