To be effective, sunglasses must block out 99 percent to 100 percent of both UV-A and UV-B radiation, says the American Optometric Association, and should screen out 75 percent to 90 percent of visible light. The association says lenses must be perfectly matched in color and free of distortion and imperfection. Neutral gray lenses are best for maintaining color perception.
Here ares some other tips to help you choose a pair of sunglasses:
Photochromatic vs. polarized lenses
- Photochromatic lenses simply change their tint. In sunlight, they darken; on a gloomy day or indoors, they lighten up. Generally, these lenses are found on more expensive sunglasses.