For best block from rays, make sure sunglasses label is specific


September 15, 1992|By Dr. Simeon Margolis | Dr. Simeon Margolis,Contributing Writer

Q: My doctor has told me to wear sunglasses to protect my eyes from exposure to ultraviolet light. What sunglasses should I buy?

A: Ultraviolet-B (UV-B) light is potentially harmful to the eyes. The American National Standards Institute has established the following three types of labels for sunglasses based on their ability to block UV-B light: special purpose, general purpose and cosmetic. The American Academy of Ophthalmology recommends you purchase general-purpose sunglasses, which are made for daily wear and may be labeled "Blocks All UV-B" or "Blocks 95 percent UV-B," unless you plan to engage in high-exposure activities such as skiing. In that case you should buy special purpose sunglasses which block at least 99 percent of UV-B light.

Cosmetic sunglasses block only 70 percent of UV-B light. Sunglasses that do not indicate the degree of absorption of UV-B light, for example labeled merely "Blocks UV," may provide inadequate protection.

There is no relationship between the color or darkness of the lens or the price of the sunglasses and their ability to filter UV light.

Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine and associate dean for faculty affairs at the school.

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