Quantitative Assessment of Early Diabetic Retinopathy Using Fractal Analysis

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 I 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 vas 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 146214 (1.45023-1.47217). After adjustment for age, sex, diabetes duration, At C, blood pressure, and total cholesterol, increasing retinal vascular fractal dimension was significantly associated with increasing odds of retinopathy (odds ratio 3.92 [95% Cl 2.02-7.61] for fourth versus first quartile of fractal dimension). In multivariate analysis each 0.01 increase in retina 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 gometric 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.