sunglasses

Sunglasses, More than an Accessory
Carol Beard, RN, BS.N., Ann C. SLocum, Ph.D., Joanne Schultink, M.S.
Human Environment and Design Department, Michigan State University

Sunglasses are often worn for fashion, or to improve vision by reducing glare, but they may also be a means of protection. There is significant danger to the eyes as a result of ultraviolet (UV) radiation exposure (Stephens and Davis, 1993). Damage to the eye can be caused by short daily exposures to high levels of UV radiation. Over long periods of time, with unprotected exposure, one might see melanomas of the eye lids, degenerative changes of the conjunctiva, acute ocular pain, cataracts, as well as macular degenerative changes (Stephens and Davis, 1993). "Studies have shown that people whose eyes are exposed to the sun for hours every day are three times as likely to develop cataracts as those who protect their eyes with approved sunglasses or brimmed hats" (Perry, 1996). For those who have had cataract surgery or who have macular degeneration, wraparound glasses are recommended (Brink, 1996). Sunglasses with UV protection can decrease these risks and this is particularly important for people who spend a lot of time outdoors.

Sunglasses vary in the amount of UV protection they provide. The only materials that will provide complete UV protection are polycarbonate and plastic with a dye that absorbs UV radiation. "Standard prescription sunglass lenses, whether . . . glass or . . . plastic, absorb all UVB radiation and approximately 85% of UVA radiation, whereas polycarbonate plastic will absorb all radiation" at lower wavelengths (Stephens and Davis, 1993).

"It is more difficult to make general statements about the UV protection provided by nonprescription sunglasses because the lens materials are obtained from a large number of sources, both domestic and foreign. Inexpensive sunglasses may provide just as much protection as more costly ones. Any polycarbonate nonprescription sunglass lens will provide complete UV protection, with the added advantage of extreme impact resistance" (Stephens and Davis, 1993). There are no current governmental (FDA) requirements for sunglass labeling or for verification of labeling claims. There is, however, a voluntary standard (ANSI Z80.3) that expresses the effectiveness of lenses, and many manufacturers now label their lenses in conformance to it. According to the standard, ". . .darkened fashion lenses, labeled cosmetic lenses must block out up to 70% of UVB and at least 20 percent of UVA light. To be labeled general purpose, lenses must block out 95% of UVB and 60% of UVA. Special purpose lenses block out 97% of UVB and at least 60% of UVA light" (Watkins, 1995). In addition, some sunglass manufacturers and importers will supply information about transmittance upon request (Stephens and Davis, 1993).

"Even with lenses that absorb 100% of UV radiation, radiation can reach the eyes from the sides and top of sunglasses. Large lenses worn close to the face provide more protection, and the use of side-shields or a deeply wrapped frame will further protect the eyes. . . . "People who spend large amounts of time outdoors should have UV protection in both their clear lenses and their sunglasses" (Stephens and Davis, 1993). "Sunglasses for eyes are like sunscreen for the skin--they protect you from burns," says John Williams, Marshfield Clinic ophthalmologist, Marshfield, Wisconsin. "Just as you wear sunscreen when you're out in the sun, you should wear sunglasses" (Tevis, 1996).

Return to SunWise Menu
Go to other detailed information

introduction	protective clothing	sunscreen, sunblock
tanning beds	references

Disclaimer, Indicia , & Project Credits