The association of iris color with eye disease in diabetes

Iris (eye) color was examined for its effect on eye disease in a population-based study of diabetic retinopathy in Wisconsin. Eye color was determined by comparing the iris in a red reflex photograph with standard photographs. In younger-onset diabetic persons (N = 996), macular edema was more prevalent in persons with blue or grey eyes (12%) compared with intermediate (9%) or brown (6%) (P = 0.04). Cataracts were more prevalent in blue or grey eyes (32%) compared with intermediate (22%) or brown (20%) in the younger-onset group (P less than 0.001). In older-onset persons (N = 1370), intraocular pressure (IOP) was higher in persons with brown eyes (17.8 mmHg) compared with blue or grey (17.1 mmHg) or intermediate (16.6 mmHg) (P = 0.012). Eye color was not associated significantly with diabetic retinopathy in either the younger- or older-onset group or with age-related macular degeneration or glaucoma in the older-onset group.