Exposure to ultraviolet (UV) light rays, the same rays that cause sunburn, can also cause cataracts, snow blindness, and damage the cornea and retina. It is possible for damage to occur in an afternoon outing or to build slowly over a period of years. Everyone should wear UV-absorbing sunglasses year round when in the sun.

Good sunglasses provide safe and comfortable vision. Protect the long-term health of your eyes by choosing sunglasses that offer maximum protection from the sun.

Labels rate glasses with an SPF (sun protection factor) rating. Buy the appropriate glasses for the sport or activity for which you require them:

Good sunglass lenses block 75 to 90 percent of visible light. This is sometimes called the "transmission factor" on labels. Take caution to protect against blue light exposure. Lenses tinted yellow, brown, or amber absorb blue light.

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. Photo chromic 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.

Article #4518

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