Incidence of cataract extraction in Pima Indians. Diabetes as a risk factor.

The incidence of visually disabling cataract was estimated by the rate of first cataract extraction in a population of Pima Indians in Arizona. The annual age-specific rates of cataract surgery (first and second eyes) were 3.7 to 5.9 times as high as the estimated US rates. Diabetes was a strong risk factor for first cataract surgery in all age and sex groups except in men aged 75 to 84 years. Overall, with age and sex controlled, the rate of first cataract surgery was 2.2 times as high (95% confidence interval, 1.3 to 3.9) in diabetic as in nondiabetic subjects. Cataract surgery was related to the duration and type of treatment of diabetes. Insulin-treated diabetics had about five times the rate of those with normal glucose tolerance. The rate of cataract surgery was lowest in subjects with normal glucose tolerance, somewhat higher in those with impaired glucose tolerance, and even higher with increasing duration of diabetes.