Five-year incidence and progression of diabetic retinopathy in a defined older population: the Blue Mountains Eye Study.

AIMS: To determine 5-year incidence and progression of diabetic retinopathy in an older Australian population-based cohort. METHODS: During the period 1992-1994, the Blue Mountains Eye Study examined 3654 residents aged 49+years (82.4% of those eligible), living in two urban postcode areas, west of Sydney, Australia. Participants were subsequently invited to attend 5-year follow-up exams. After excluding 543 (14.8%) who died during the follow-up period, 2334 persons (75.0%) were re-examined during 1997-1999. The examination included a comprehensive questionnaire, blood pressure measurement, standardised refraction, Zeiss stereo retinal photographs, and estimation of fasting blood glucose. Diabetic retinopathy was graded from the retinal photographs, using the modified Early Treatment Diabetic Retinopathy Scale classification (15-step scale). RESULTS: Of participants with diabetes diagnosed at baseline, 150 were re-examined, including 139 with gradable fundus photographs. The cumulative 5-year incidence of diabetic retinopathy was 22.2% before 95% confidence interval (CI) 14.1-32.2%. Retinopathy progression (1+ steps) was documented in 25.9% (95% CI 18.8-34.0%) of participants with retinopathy and gradable photographs at both visits; in 58.3% of these cases, a 2+ -step progression was documented. Progression to proliferative retinopathy occurred in only 4.1% of those with retinopathy at baseline. The only baseline risk factors associated with retinopathy progression, after adjusting for age and gender, were increase in fasting blood glucose, odds ratio (OR) 1.2 (95% CI 1.1-1.4)/mmol/l, and increase in diabetes duration, OR 2.3 (95% CI 1.0-5.3)/10 years. CONCLUSIONS: These data provide 5-year cumulative incidence of diabetic retinopathy in a defined older population. Increase in diabetes duration and elevated baseline fasting blood glucose level predicted retinopathy incidence.

Five-year incidence and progression of vascular retinopathy in persons without diabetes: the Blue Mountains Eye Study.

PURPOSE: To assess the 5-year incidence of vascular retinopathy and its associations in an older nondiabetic population. METHODS: The Blue Mountains Eye Study examined 3654 residents aged 49+ years (82.4% response rate) during 1992-1994, and re-examined 2335 (75.1% of survivors) during 1997-1999. Retinopathy lesions (microaneurysms, haemorrhages, hard or soft exudates) were assessed from 6-field retinal photographs in persons without diabetes. Incident retinopathy was assessed in those at risk. Hypertensive status was defined following the WHO/International Society of Hypertension guidelines. RESULTS: Of the 2335 re-examined, 195 had retinopathy lesions at baseline and 1725 were at risk of retinopathy after excluding subjects with diabetes (n=261), retinal vein occlusion (n=52) or missing/un-gradable photographs (n=102). The cumulative 5-year incidence was 9.7% (95% confidence intervals (CI) 8.3-11.1%). Age was the only factor significantly associated with incident retinopathy (Pfor trend=0.012). Neither fasting blood glucose (age-sex-adjusted P=0.147) nor hypertension (adjusted Pfor trend=0.43) was associated with incident retinopathy. Of the 195 with retinopathy lesions at baseline, 3.5% developed diabetes, 13.3% progressed, and 72.3% regressed/disappeared over 5 years. Progression was positively associated with elevated blood pressure (BP) (adjusted odds ratio (OR) 1.3, 95% CI 1.1-1.6 per 10 mmHg systolic BP) and inversely associated with fasting glucose level (OR 0.36, CI 0.14-0.92 per mmol/l increase). Aspirin use was weakly associated with regression (OR 2.4, CI 1.0-6.0). CONCLUSIONS: Over 5 years, retinopathy developed in 10% of older people without diabetes, while 72% of baseline lesions regressed. Age was significantly associated with the development of these lesions.