Sunglasses are popular for comfort and fashion, but now there is medical evidence supporting the use of sunglasses to protect the long-term health of the eyes by limiting their exposure to ultraviolet (UV) light.

More than a dozen studies have shown that spending hours in the sun without proper eye protection can increase the chances of developing age-related eye diseases like cataracts and macular degeneration. Ophthalmologists (Eye M.D.s) now recommend wearing UV-absorbent sunglasses and wide-brimmed hats when in the sun long enough to get a suntan or sunburn.

People mistakenly confuse the ability of sunglasses to block UV light with the color and darkness of the lenses. In truth, UV protection comes from a chemical coating applied to the surface of the lens. Shop for sunglasses that absorb 99% to 100% of all UV light. Some lens manufacturers’ labels say "UV absorption up to 400 nm." This is the same thing as 100% UV absorption.

In addition to UV light, sunlight also has low levels of infrared light rays. Infrared wavelengths are invisible and produce heat. The eye seems to tolerate infrared well. Research has not shown a connection between eye disease and infrared light ray exposure.

Polarized lenses cut reflected glare, such as sunlight bouncing off water, pavement, or snow. Sunglasses with polarized lenses are popular and useful for fishing, driving, and skiing. Polarization has nothing to do with UV light absorption, but many polarized lenses are now made with a UV-blocking substance.

Wraparound sunglasses are shaped to keep light from shining around the frames and into the eyes. Studies have shown that enough UV rays enter around ordinary frames to reduce the benefits of protective lenses. Large-framed, close-fitting wraparound sunglasses protect the eyes from all angles. Wraparound sunglasses should be considered by commercial fishermen, mountain climbers, skiers, or anyone who spends time at high altitudes or on the water.

(c) 2007 The American Academy of Ophthalmology