Abstract

Progressive addition spectacle lenses (PALs) are now an integral part of spectacle lens dispensing. The first design is attributed Aves (1907), and used two aspheric surfaces of revolution. This design was characteristic of a number which appeared later, such as the Omnifocal (Volk and Weinberg, 1962), in that the power progressed continuously down the whole aperture of the lens. The main problem with this is at distance, where the lack of a large stabilised reading zone could be a considerable visual handicap to the wearer. A further problem with the Aves type of design is that using two aspheric surfaces would make the incorporation of prescription cylinders extremely difficult.

© 1992 Optical Society of America