Photochromic Sunglasses - Polarized Chameleon Glasses for DrivingAn important note about photochromic lenses: Because they react to UV light and not to visible light, there are circumstances under which the darkening will not occur. Frist example, is in your car. Because the windshield blocks out most UV light, photochromic lenses will not darken. Second,is indoors test with ordinary lighting(Because the lighting used in daily lighting does not contain ultraviolet light),photochromic lenses will not darken. So the