Ultraviolet radiation and the eye.

Moderate exposure to ultraviolet radiation (UVR) from the sun is a necessary part of maintaining normal health. Ultraviolet radiation is critical for formation of VitaminD and the normal healthy growth of bones and teeth. However, excessive exposure to UVR has no health benefits and can lead to adverse consequences for the skin and eye. When the body receives excessive UVR exposure on a chronic or acute basis, the potential for cellular and tissue damage exists. Ultraviolet B radiation (UVB) is implicated in the development of periocular skin changes, such as sunburn and eyelid malignancies, and diseases of the conjunctiva, cornea, and lens. Significant advances have beenmade toward understanding the effects of UVR on the eye on a biochemical, environmental, and epidemiologic level. Each individual is exposed to a variable amount of harmful UVB, which is dependent on environmental factors such as cloud cover, lower atmospheric pollution, and the thickness of the ozone layer, geographical considerations such as latitude and altitude, temporal factors such as time of day and season, and personal behaviors such as the use of protective clothing, lotions, and eyewear. To limit exposure to UVB, the most modifiable of these factors is the use of brimmed hats and sunglasses, as personal protection measures can effectuate up to an 18-fold difference in ocular UVB exposure. Human exposure to UVR is increasing as ozone depletion and global climate changes influence surface radiation levels, life expectancy increases, and lifestyle changes lead to increased leisure activities in UV intense environments. Increased exposure to UVR has broad public health implications for ophthalmologists as an increased burden of UVrelated ocular disease is to be expected.