Abstract
Purpose: :
Fractal analysis has been used recently to evaluate altered patterns or branching densities of the retinal vascular tree. The goal of this study was to investigate the relationship between retinal fractal dimensions and retinal circulation, which is impaired in early-stage diabetic retinopathy (DR) (Nagaoka et al., IOVS, in press) in patients with type 2 diabetes mellitus.
Methods: :
Using a laser Doppler velocimetry system (CLBF Model 100, Canon, Tokyo, Japan), we measured the retinal vessel diameter (D) and blood velocity (V) and calculated the retinal blood flow (RBF) in the retinal arterioles and venules in 106 eyes (106 patients, mean age ± SD, 58.7 ± 9.8 years). The patients with type 2 diabetes mellitus had no (n=86) or background DR (n=20). The fractal dimensions (Df) were measured on retinal photographs using a semiautomatic computer-based program.
Results: :
The average D, V, and RBF in the retinal arterioles and venules were, respectively, 107.9 ± 13.3 and 139.4 ± 20.1 µm, 33.2 ± 7.0 and 22.6 ± 6.1 mm/sec, and 10.4 ± 3.8 and 9.3 ± 2.9 µl/min. The average Df was 1.4276 ± 0.0193. There were no differences between the retinal fractal dimensions and any retinal circulatory parameters of the retinal arterioles. In contrast, we found significant correlations between retinal fractal dimensions and the vessel D (r=0.37, p=0.0002) and RBF (r=0.22, p=0.026) in the retinal venules.
Conclusions: :
Our results indicated that the retinal fractal dimensions may be associated with changes in the retinal circulation in patients with type 2 diabetes mellitus.
Keywords: diabetic retinopathy • clinical (human) or epidemiologic studies: systems/equipment/techniques • clinical research methodology