The SAA recommends against wearing sunglasses during night driving. So-called night driving glasses are generally amber tinted eyewear meant to reduce the glare of oncoming headlights. While they may make the driver feel more comfortable, they also reduce the wearers visibility of the darker portions of the roadway. There are many lens treatments, lens performance types and lens materials, many of which are combined in concert to make the lens options available today. Sunglass lens treatments are many and varied.
Tints vary from light to medium to dark and very dark.
Gradient tinted lenses are darker at the top and lighter at the bottom to cut overhead glare and provide clearer vision straight ahead and when looking down. Double gradient lenses are darker at the top and bottom and lighter in the center to cut overhead and reflected glare from the ground and provides clearer vision and straight ahead. Photochromic lenses appear lighter indoors since they darken in sunlight and fade indoors to provide comfort according to the brightness of the environment. Polarizing lenses selectively absorb horizontally reflected glare from surfaces such as water or roadways to improve visibility. Contrast Enhancing lenses are designed to provide better visibility through contrast enhancement under certain conditions.