Photochromic Lenses
Photochromic lenses have a special chemical coating that makes them change to a dark tint in the sunlight and turn clear indoors. Photochromic lenses are great for people who do not wish to carry a separate pair of prescription sunglasses. It is important to recognize that these lenses do not darken as well while driving a car. The windshield prevents most of the UV light from reaching the lens.
Sensity - Light Reactive Lenses from Hoya Vision US on Vimeo.