Visual acuity in a diabetic population.

In a population study of all insulin-treated diabetics and a random sample of those treated with oral antihyperglycaemic agents (OHA) in Gotland, Sweden, the visual acuity (VA) was determined. The prevalence rates of visual impairment (VA 0.1-0.2) and blindness (VA less than 0.1) in the insulin-treated group were 4.9 and 4.4%, respectively, and in OHA-treated diabetics 7.2 and 1.4%. The impairment and blindness were due to diabetic retinopathy (Rp) in 72% of the insulin-treated group, but only in 14% of the OHA-treated diabetics in whom cataract and age-related maculopathy were the predominant causes. Blindness was four times more frequent among insulin-treated females than males. On simple logistic regression test VA correlated with Rp, age at examination, age at onset of diabetes, duration of diabetes and sex. However, on multiple logistic regression analysis the only significant relationships with VA were in the insulin-treated group, a correlation with Rp and age; and in the OHA-treated group, a correlation with age only. Thus the higher frequency of blindness in insulin-treated women was explained by Rp and age. When standardizing for age, the fraction of blind patients was found to be significantly higher among the insulin-treated than in the OHA-treated diabetics (6.7 vs 1.4%).