Plastic lenses - Part 1: Single vision lenses

摘要

Organic lens materials have come a long way since their first use in ophthalmic lens production over 50 years ago. Then there was only one material, Perspex (methyl methacrylate), but now there are six main types, giving ample scope for lens designers and dispensers for supplying the 'best fit' lens for almost all patients and prescriptions. Perspex, originally introduced to the market by COIL (Combined Optical Industries - now part of the Carclo Group), and sold under the trade name of Igard, was a great step forward, as it allowed wearers to have a lens that was far safer than the only other material then on the market - glass. Lenses produced from it were also much lighter in weight than those made from glass. It did, however, suffer from one serious drawback; it is a very soft material and therefore scratched very easily.