Quantitative Assessment of Early Diabetic Retinopathy Using Fractal Analysis
- Ning Cheung, MBBS1,
- Kim C. Donaghue, MBBS, PHD2,
- Gerald Liew, MBBS, MMED3,
- Sophie L. Rogers, MEPI1,
- Jie Jin Wang, PHD13,
- Shueh-Wen Lim, BMEDSCI1,
- Alicia J. Jenkins, MBBS, MD4,
- Wynne Hsu, PHD5,
- Mong Li Lee, PHD6 and
- Tien Y. Wong, MBBS, PHD16
- 1Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- 2The Children's Hospital at Westmead, University of Sydney, Sydney, Australia
- 3Centre for Vision Research, University of Sydney, Sydney, Australia
- 4Department of Medicine, St. Vincent's Hospital, University of Melbourne, Melbourne, Australia
- 5School of Computing, National University of Singapore, Singapore
- 6Singapore Eye Research Institute, National University of Singapore, Singapore
- Corresponding author: Dr. Ning Cheung, dannycheung{at}hotmail.com
Abstract
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.
Footnotes
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Published ahead of print at http://care.diabetesjournals.org on 3 October 2008.
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- Accepted September 23, 2008.
- Received July 4, 2008.
- DIABETES CARE
