Centre for Eye Research Australia (CERA) - Research Publications
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ItemQuantitative Assessment of Early Diabetic Retinopathy Using Fractal Analysis(AMER DIABETES ASSOC, 2009-01)OBJECTIVE: Fractal analysis can quantify the geometric complexity of the retinal vascular branching pattern and may therefore offer a new method to quantify early diabetic microvascular damage. In this study, we examined the relationship between retinal fractal dimension and retinopathy in young individuals with type 1 diabetes. RESEARCH DESIGN AND METHODS: We conducted a cross-sectional study of 729 patients with type 1 diabetes (aged 12-20 years) who had seven-field stereoscopic retinal photographs taken of both eyes. From these photographs, retinopathy was graded according to the modified Airlie House classification, and fractal dimension was quantified using a computer-based program following a standardized protocol. RESULTS: In this study, 137 patients (18.8%) had diabetic retinopathy signs; of these, 105 had mild retinopathy. Median (interquartile range) retinal fractal dimension was 1.46214 (1.45023-1.47217). After adjustment for age, sex, diabetes duration, A1C, blood pressure, and total cholesterol, increasing retinal vascular fractal dimension was significantly associated with increasing odds of retinopathy (odds ratio 3.92 [95% CI 2.02-7.61] for fourth versus first quartile of fractal dimension). In multivariate analysis, each 0.01 increase in retinal vascular fractal dimension was associated with a nearly 40% increased odds of retinopathy (1.37 [1.21-1.56]). This association remained after additional adjustment for retinal vascular caliber. CONCLUSIONS: Greater retinal fractal dimension, representing increased geometric complexity of the retinal vasculature, is independently associated with early diabetic retinopathy signs in type 1 diabetes. Fractal analysis of fundus photographs may allow quantitative measurement of early diabetic microvascular damage.
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ItemLongitudinal association of glucose metabolism with retinopathy - Results from the Australian Diabetes Obesity and Lifestyle (AusDiab) study(AMER DIABETES ASSOC, 2008-07)OBJECTIVE: We determined the longitudinal association of glucose metabolism with retinopathy in a sample of the Australian population. RESEARCH DESIGN AND METHODS: The Australian Diabetes Obesity and Lifestyle (AusDiab) study is a national, longitudinal study of adults aged > or =25 years from 42 randomly selected areas of Australia. Retinopathy was assessed at baseline in 1999-2000 and 5 years later in 2004-2005 in participants identified as having diabetes (based on self-report and oral glucose tolerance test) and impaired glucose metabolism and in a random sample with normal glucose tolerance. Complete retinal data were available for 1,192 participants. Photographs were graded at two time points according to a simplified version of the Wisconsin grading system. RESULTS: The 5-year incidences of retinopathy were 13.9 and 3.0% among those with known and newly diagnosed diabetes at baseline, respectively. Of those who developed incident newly diagnosed diabetes at follow-up, 11.9% had retinopathy at baseline compared with 5.6% of those who did not progress to incident newly diagnosed diabetes (P = 0.037). After adjustment for factors identified as risk factors for diabetes, individuals with retinopathy signs at baseline were twice as likely to develop incident newly diagnosed diabetes compared with those who did not have retinopathy signs at baseline. CONCLUSIONS: The 5-year incidence of retinopathy was 13.9% among individuals with known diabetes. Nondiabetic individuals with retinopathy signs at baseline had a twofold higher risk of developing incident newly diagnosed diabetes 5 years later. This result provides further evidence that mild retinopathy signs may be a preclinical marker of underlying microvascular disease and future diabetes risk.