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2019 | Tehama County Medical Guide | 5 e effects of UV rays on the eyes The sun can be both friend and foe. A warm, sunny day can improve mood and increase levels of vitamin D in the body. Exposure to sunlight during the day also can help regulate the body's natural sleep-wake cycle, known as the circadian rhythm. However, over- exposure to the sun can be dangerous as well. Many people recognize that exposure to the sun can lead to sunburn and long-standing skin damage, but they may not realize that the eyes also are susceptible to damage caused by the sun. The eye health resource All About Vision warns that extended exposure to the sun's UV rays has been linked to significant eye problems, includ- ing cataracts, macular degeneration, pinguecula, pterygia, and photokerati- tis. UV rays come in three types: A, B and C. The atmosphere's ozone layer blocks virtually all UVC rays, which are the most potent, but UVA and UVB can be dangerous when exposure to the sun is significant. Exposure to excessive amounts of UV radiation over a short period of time can cause photokeratitis, which is es- sentially a sunburn of the eye that can cause pain and redness. Prolonged exposure to UV rays without adequate protection may cause lasting damage, says the American Optometric Associ- ation. UV rays come from both the sun itself and tanning beds. Here's a look at some of the common UV-induced eye conditions. • Cataracts: A clouding of the eye's natural lens, or the part of the eye that focuses the light a person sees. • Macular degeneration: UV rays may lead to macular degeneration, which is a leading cause of vision loss for older people. The macula is the center portion of the retina, essential for vision. • Pterygium: This is a growth that be- gins on the white of the eye and may involve the cornea. The growth can eventually impede vision, says the or- ganization Prevent Blindness America. Sunglasses and other protective lenses are essential to keeping the eyes healthy. AOA says that for sun- glasses to be effective, they should: • block out 99 to 100 percent of both UV-A and UV-B radiation; • screen out 75 to 90 percent of visible light; • have lenses that are perfectly matched in color and free of distortion and imperfection; and • have lenses that are gray for proper color recognition. In addition, people can wear wide- brimmed hats to protect their eyes from the sun and harmful UV rays. This will shield the eyes and the deli- cate skin of the face. Learn more about protecting the eyes at www.allaboutvision.com, www.aoa. org, or www.preventblindnessamerica. org.

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