Retinopathy data from 624 patients with a type 2 diabetes duration of 20-30 years (group A) were analyzed by stratifying patients according to age of onset of diabetes and glycemic control. Retinopathy status was scored clinically as per a modified Early Treatment Diabetic Retinopathy Study (ETDRS) severity scale. To obviate possible bias due to a higher attrition from comorbidities in those with later-onset diabetes and retinopathy, 852 patients with type 2 diabetes of shorter duration (10-12 years, group B) were similarly studied.
Malukiewicz G., Lesiewska-Junk H., Kaźmierczak K. Changes in the colour vision and contrast sensitivity in diabetic patients without retinopathy. Klin Oczna. 2009;111(7-9):221-3.