Large sunglasses are better than small ones because they protect against light coming in from the sides, top, and bottom of the frames. Glasses that slip even a quarter inch from the forehead allow about 20 percent more UV rays into the eyes. Be sure to test sunglasses for distortion. Hold them at arm's length and look at a straight line in the distance. If the line sways or bends when the glasses are slowly moved, the lenses are of poor quality.
Polarized lenses are good for cutting reflected glare.
Mirrored lenses reflect light and are good for water and snow sports. Photochromic lenses respond to the intensity of UV light by lightening or darkening according to brightness. Gradient lenses are darker at the top than at the bottom. Each of these lenses must be specially treated to guard against UV rays and blue light. All Rights Reserved.