Future of Optics: The shape of lenses to come

Perhaps the most important development in the ophthalmic lens field during the first two decades of the 21st century has been the rapid rise in the use of CNC (computer numerical control) machining techniques in the ophthalmic prescription industry. Popularly known as freeform, this method of working enables almost any form of surface to be produced, provided that the laboratory has access to the software necessary to describe and produce the surface during the generation procedure. Indeed, the key to freeform production is the software that calculates the curves for the individual designs and drives the machinery to manufacture the lenses. The optimal curves are calculated for every possible prescribed power at thousands of points on the lens surface resulting in a ‘point file’ that describes, in mathematical terms, the surface of the lens. This file is ultimately used to drive the production generator and polisher used to manufacture the lens.