This book describes in simple terms the theory, manufacturing process and prescription of spectacle lenses and frame materials. It serves as an introduction to ophthalmic prescription work for those newly joining the industry, either in a production laboratory or a small workshop. New for the third completely updated and revised, this book still retains the uniquely understandable approach of the original editions by Arthur Bennett; much new material has been added in light of recent developments; there are many new illustrations and existing ones have been updated; and the format has been completely redesigned allowing easier access to the information. This classic text will continue to be an invaluable introduction for everyone entering the field of retail and manufacturing optics including dispensing opticians, optical assistants, technicians and receptionists.