Tinted Spectacle Lenses: Part 2

This article follows on from Part 1 in which we considered the main methods of tinting spectacle lenses. Now we will look in more detail at specialist and more modern tinting methods & lens finishes. Photochromic (Adaptive) lenses have been around for some time – since the early 1960’s in mineral (glass) material & became hugely popular in the 1970’s bearing the trademark Reactolite® & later Reactolite Rapide®. The term Photochromic comes from two Greek words – Photos which means light & Chroma meaning colour. At its most basic a photochromic lens is one which changes colour because of light. Early lenses darkened quickly on exposure to light but took a long time to return to their clear unreacted state. This ‘vintage’ advertising poster says the lenses ‘darken in 30 seconds’ but clear ‘fast’ on return indoors – they do not quantify ‘fast’!  Photo: The Nostalgia Shop