Dear Dr. SerVaas: I have read that UV protection in glasses is not directly related to the lens tint. If this is the case, can indoor reading glasses be treated for UV protection and used in the sun?Also, I have a collection of sunglasses bought through the years. How can I find out which of these provide adequate UV protection? Can this be checked? Is there a difference in the amount of UV protection in glasses that are sold as having UV protection? Who determines what the proper amount of protection is? Dear Reader: Your tinted lenses that look like sunglasses may not provide adequate filtration of solar radiation. Ultraviolet A and B are the wavelengths of concern, according to Dr. Fred Hasselbrinck (O.D.), who responds to your questions: "UVB, the classic sunburn rays, can cause eye discomfort, as in 'welder's flash' and 'snow blindness.' UVA rays pass through the front layers of the eye and can advance the formation of cataracts. While a dark lens tint reduces glare and affords comfortable viewing, UV-protective coatings can be practically colorless. "The majority of corrective lenses are cut from plastic. Those considered 'high index' have very good UV absorption. Other means of UV protection may be added during the manufacture or cutting of a lens. These additives may be used with other tints to provide glare reduction or fashion coloring. "Indoor reading glasses with plastic lenses can be treated to block UV radiation. Most opticians, however, recommend a lens treated during its manufacture. "Spectacle lenses can be checked for UV absorption using a device that is called a photometer, or UV meter. Most eye care providers have this equipment. The American National Standards Institute (ANSI) sets guidelines for ultraviolet protection. An absorption rate of 99.8 percent of UV-B rays and 70 percent of UV-A rays is required to be designated 'UV absorbing.'" An optometrist or doctor of optometry (O.D.) is clinically trained and state licensed to examine the eye and vision system, diagnose vision problems and eye diseases, prescribe glasses or contact lenses, and provide referrals.
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