Progressive addition and variable focus lenses: a review.

Abstract

This paper reviews recent developments in the field of progressive addition spectacle lenses and variable focus lens systems design. The study is a sequel to the previous analytical work of von Rohr (1916), Graham (1942), and Bennett (1970). A brief history of the work documented by the aforementioned authors is presented. Comparative assessment is undertaken of the most recent patents of progressive addition and variable focus spectacle lenses. A largely verbal description is employed because patent literature is often devoid of mathematical models.