Abstract
Purpose: :
Blindness is among the most feared complications of type 1 diabetes. The aim of this study was to examine the prevalence of blindness in a population-based cohort of type 1 diabetic patients and to evaluate predictors of blindness in a 25-year follow-up.
Methods: :
In the Danish County of Fyn, we have previously identified all insulin-treated diabetic patients with an onset before the age of 30 as of 1 July 1973 (n=727). Diabetic retinopathy and other complications were recorded between 1 June 1981 and 1 June 1982 in a clinical baseline-examination in which 573 of 627 (91.4%) patients still alive and living in Denmark participated.In January 2007 data on blindness were collected from the Danish Association of the Blind and related to the baseline-examination in 1981-1982. The Danish Association of the Blind is a voluntary organization open for all patients with a best-corrected visual acuity in the best eye at or below 0,1.
Results: :
Of the 573 patients examined at baseline in 1981-1982, 65 (11.3%) were at some point registered as blind. Median age at registration at the Danish Association of the Blind was 49.7 years corresponding to a median duration of diabetes of 31 years.At baseline, 140 patients (24.4%) had no retinopathy, 290 (50.6%) had non-proliferative retinopathy, 119 (20.7%) had proliferative retinopathy, and 24 (4.2%) were blind already.Forty one patients went blind in the 25-year observation period after the baseline examination. Incidence of blindness was 4.3%, 6.2%, and 14.3% among patients with no retinopathy, non-proliferative retinopathy and proliferative retinopathy, respectively. For the three groups, time from baseline-examination to blindness was in median 17.9 years, 10.0 years, and 6.4 years, respectively.
Conclusions: :
Blindness is a major issue among type 1 diabetic patients. In a population-based cohort 11.3% were at some point registered blind between 1973 and 2007. Loss of sight was related to the level of retinopathy at baseline-examination in 1981-1982. Fourteen point three percent of patients with proliferative retinopathy ended up blind.
Keywords: diabetes • visual acuity • clinical (human) or epidemiologic studies: risk factor assessment