Essilor hosts a free CET article open to all UK registered Optometrists and Dispensing Opticians.
This article is written by Professor Mo Jalie SMSA, FBDO (Hons), Hon FCGI, Hon FCOptom, MIMgt. Professor Jalie is visiting Professor in Optometry at the University of Ulster, Coleraine. He taught ophthalmic lenses and dispensing in the Department of Applied Optics, City & East London College for thirty years and was Head of Department from 1985 to 1995.
This article takes a detailed look at the impact of moving the progressive surface from the front to the rear of a lens. The article covers an overview of the Minkwitz theorem, which highlights the affect of progression length on unwanted astigmatism. Professor Jalie given a detailed explanation along with field of view calculations through a progressive lens with the progression on both the rear and front lens surfaces. An overview of the latest �free-form� surfacing generators is also given.
Learning Objectives:
Following this article delegates will have a much greater understanding of,
- How the length of the progression affects the amount of unwanted surface astigmatis
- How the field of view is specified for a spectacle lens
- How the position of a progressive surface affects field of view, and
- How the latest surfacing technology allows for the location of the progressive surface to be placed on the rear or front surface of the lens