Method for blocking a contact lens button

Abstract

A contact lens button and a block are integrally formed together when the contact lens button is cast in a cup having an aperture formed in the center of the bottom wall of the cup. The block has a first elongated end forming a spindle and a second end which is of circular, generally planar configuration. The spindle end is inserted through the aperture in the bottom wall of the cup providing an interference fit with the circular end portion located inside the cup spaced parallel to and slightly upwardly from the bottom wall, and the first spindle end extends exteriorly of the cup. A quantity of liquid lens material is dispensed into the cup, completely surrounding the circular end portion of the block. The material cures around the block second end, with the formed button and block removable from the cup as a single unit. The block first end is secured to a lathe chuck for rotating the button to cut the concave base surface of the lens. A front curve block is then removably secured to the base curve surface and inserted into a lathe chuck for cutting the convex power curve into the button while previously or simultaneously cutting away the block. The block sets the turning axis of the button and assists in transferring the turning axis over to the front curve block.