Verbesserungen in/oder bezüglich der Herstellung von ophtalmischen Linsen

摘要

A button for forming a segment of a multifocal lens, the button comprising a first portion (11) composed of a lead oxide-containing glass, a second portion (12) composed of a glass which contains substantially no lead oxide, the first and second portions being adjacent and forming a face of a button for machining to a desired shape, and a third portion (82) composed of a glass which contains substantially no lead oxide, the first and second glass portions being fused to the third glass portion on a side of the first and second portions remote from the said face of the button. The invention also provides a method of making a multifocal lens by (a) providing a button in accordance with the invention; (b) machining the said face of the button to the desired shape to match a recess in a lens blank; (c) disposing the button in the recess with the machined face adjacent to the face of the recess; (d) fusing the button in the recess; and (e) removing by grinding the third portion, and unwanted regions of the first and second portions so as to form a desired lens surface.