Five‐year incidence of diabetic retinopathy in the Melbourne Visual Impairment Project

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Abstract
Background: The purpose of the present paper was to describe the 5-year incidence and progression of diabetic retinopathy in the Melbourne Visual Impairment Project (VIP) cohort. Methods: Baseline examinations were conducted from 1992 to 1994 and follow-up data were collected 5 years later. Data collected during the baseline and follow-up studies included medical history (including previous diag­nosis of diabetes mellitus) and dilated fundus examination. Two 30° stereoscopic fundus photographs were taken with a Topcon TRC fundus camera, one centred on the optic disc and the other centred on the fovea. Photographs from participants who reported having diabetes were graded for diabetic retinopathy based on an extension of the Modified Airlie House Classification. Grouping of participant data into retinopathy grades was based on the results of the worst eye. Results: The follow-up survey included 82% (n = 121) of those with diabetes at baseline. Prevalence of any retino­pathy was 35.7% and macular oedema was 13% at follow up. Diabetic retinopathy was newly detected in 8/73 (5-year incidence = 11.0%, 95% confidence interval (CI) = 3.8−18.1). Disease progression was seen in 9/31 participants (29.0%, 95%CI = 14.9−47.8) who had diabetic retinopathy at baseline. The 5-year incidence of proliferative diabetic retino­pathy in people without proliferative diabetic retinopathy at baseline was 2.9% (3/104, 95%CI = 0−6.4). The 5-year incidence of macular oedema in people who did not have macular oedema at baseline was 8.0% (8/100, 95%CI = 2.7−13.3). All people with proliferative diabetic retinopathy at baseline had received laser treatment by the follow-up survey. Twenty-four per cent of people without diabetic retinopathy reported never having had a dilated fundus examination (excluding the VIP examinations). Conclusion: The 5-year incidence of diabetic retinopathy was 11% in the Melbourne Visual Impairment Project. Most people with proliferative diabetic retinopathy or macular oedema are receiving treatment. However, many people with diabetes are not having regular dilated fundus examinations.