Effect of Ultraviolet Radiation on Cataract Formation

To investigate the relation of ultraviolet radiation and cataract formation, we undertook an epidemiologc survey of 838 watermen (mean age, 53 years) who worked on Chesapeake Bay. The annual ocular exposure was calculated from the age of 16 for each waterman by combining a detailed occupational history with laboratory and field measurements of sun exposure. Cataracts were graded by ophthalmologic examination for both type and severity. Some degree of cortical cataract was found in 111 of the watermen (13 percent), and some degree of nuclear cataract in 229 (27 percent). Logistic regression analysis showed that high cumulative levels of ultraviolet B exposure significantly increased the risk of cortical cataract (regression coefficient, 0.70; P = 0.04). A doubling of cumulative exposure increased the risk of cortical cataract by a factor of 1.60 (95 percent confidence interval, 1.01 to 2.64). Those whose annual average exposure was in the upper quartile had a risk increased by 3.30 (confidence interval, 0.90 to 9.97) as compared with those in the lowest quartile. Analysis using a serially additive expected-dose model showed that watermen with cortical lens opacities had a 21 percent higher average annual exposure to ultraviolet B (t-test, 2.23; P = 0.03). No association was found between nuclear cataracts and ultraviolet B exposure or between cataracts and ultraviolet A exposure. We conclude that there is an association between exposure to ultraviolet B radiation and cataract formation, which supports the need for ocular protection from ultraviolet B. (N Engl J Med 1988; 319:1429–33.) THERE are photobiologic, biochemical, and experimental reasons to suppose that exposure to sunlight, specifically ultraviolet radiation, may be a cause of senile cataracts, 1 2 3 4 5 although firm epidemiologic evidence has been lacking. Cataracts occur more commonly in tropical or sunny areas than in more temperate regions. 6 7 8 9 Studies in Australian aborigines have shown a dose–response relation between the prevalence of cataracts and levels of ultraviolet B radiation. 10 , 11 In the United States, data from the National Health and Nutrition Examination Survey have suggested that people with higher exposures to sunlight or ultraviolet-radiation levels have an increased risk of cataract, specifically cortical cataract. 8 , 12 , 13 However, these . . .