Your eyes (like your skin) need protection from ultra violet light. Over exposure to ultra violet (UV) light can cause cataracts, degeneration of the retina, and even sunburn. The eye area skin is exceptionally delicate and can also suffer burn and irritation, so if possible, your sunglasses should wrap around the eye area and hug the face, preventing UV light from entering the eye area from above, beside, and below.
According to the American Optometry Association, sunglasses should:
1. Block out 99-100 percent of UVA/UVB radiation
2. Screen out 75-90 percent of visible light
3. Be perfectly matched in color and free of distortion and imperfection
4. Have lenses that are gray, green, or brown (preferably gray)