In addition to visible light, the sun gives off ultraviolet radiation. This radiation is divided into three types: UV-A, UV-B, and UV-C. The earth's ozone layer absorbs UV-C radiation, leaving sunglasses to protect against UV-A and UV-B rays.
Studies indicate that long-term exposure to UV-A and UV-B can contribute to the development of cataracts; retinal problems; benign growths on the eye's surface; cancer of the eyelids and skin around the eyes; and photokeratitis, a temporary but painful sunburn of the eye's surface.
"The sun's brightness creates a disabling glare that interferes with comfortable vision and the ability to see clearly," adds Dr. Freeman. It causes eyes to squint and to water. This glare occurs on cloudy as well as sunny days. When near water such as lakes and swimming pools reflected light makes the glare worse. Polarized sunglasses give added protection in those situations.
The best protection against the sun's damaging rays is consistent use of sunglasses. Use the following tips when selecting your next pair of sunglasses. For optimum sun protection, the sunglasses should: