Photochromic lenses incorporate technology of reversible change of color upon sunlight exposure and UV light: they get darker under bright lighten and lighten up under dim light. When Photochromic lenses are exposed to ultraviolet (UV) rays as in direct sunlight, a chemical process of organic photochromic molecules intervene and cause shape changing and absorbing a significant percentage of visible light and the effect is the lenses darken. On the opposite, as soon as the Photochromic lens is removed from direct and strong source of UV rays, the photochromic compounds return to their transparent state.

Thermal process is the reason photochromic compounds fade back to their clear state, the higher the temperature, the less dark photochromic lenses will be; this thermal effect prevents Photochromic lenses become very dark in very hot weather and conversely, in cold weather conditions they will get very dark. Consequently, as soon as the lenses are not anymore in the triggering UV light, the photochromic lenses exposed to cold weather take longer to regain their transparency in comparison with the ones submitted to warm temperature.

Producing normal prescription in Photochromic lenses, it offers 100% UV protection of the eyes indoors and out all the times and it eliminates the need for a separate pair of prescription sunglasses.