Photochromic lenses contain UV-sensitive substances that change their chemical structure according to the intensity of the light. The lens has a light base color that becomes darker when sunlight is more intense, to quickly return to the initial color when the light decreases. This technology allows you to always wear glasses moving from shadow areas to particularly bright areas and vice versa. The colors available are CRX bronze and smoke (category change from 1 to 3) available on models 019 005; bronze (change of category from 2 to 4) on models 59G-008 007 and transparent (change of category from 0 to 2) on model 838.