Tromsø eye study: prevalence and risk factors of diabetic retinopathy.
To determine the prevalence of visual impairment, retinopathy and macular oedema, and assess risk factors for retinopathy in persons with diabetes. The present study included 514 participants with diabetes aged 46-87 years from the Tromsø Eye Study, a sub-study of the population-based Tromsø Study in Norway. Visual acuity was measured using an auto-refractor. Retinal images from both eyes were graded for retinopathy and macular oedema. We collected data on risk factor exposure from self-report questionnaires, clinical examinations, laboratory measurements and case note reviews. Regression models assessed the cross-sectional relationship between potential risk factors and diabetic retinopathy. The prevalence of visual impairment (corrected Snellen visual acuity <20/60 in the better-seeing eye) was 1.6%. The prevalence of diabetic retinopathy was 26.8% and macular oedema 3.9%. In a multivariable logistic regression model, retinopathy was associated with longer diabetes duration (odds ratio, OR 1.07, 95% CI 1.03-1.11), insulin use (OR 2.14, 95% CI 1.19-3.85), nonfasting glucose (OR 1.07, 95% CI 1.00-1.15) and microalbuminuria (OR 1.89, 95% CI 1.28-2.81). Sub-group analyses showed association between retinopathy and even low levels of microalbuminuria (1.16 mg/mmol). The findings suggest that low levels of microalbuminuria may be a useful risk predictor for identifying individuals with diabetes at high risk of retinopathy. The study confirms previous findings that insulin use, longer diabetes duration and higher levels of blood glucose are associated with retinopathy in persons with diabetes. The prevalence of diabetic retinopathy was similar as reported in other studies.