Relationship between retinal fractal dimensions and retinal circulation in patients with type 2 diabetes mellitus

To investigate the relationship between retinal fractal dimensions (Dfs) and retinal circulation, which is impaired in early-stage diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (DM).

Using a laser Doppler velocimetry system, 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 ± standard deviation, 58.7 ± 9.8 years). Patients with type 2 DM had no (n = 86) or mild nonproliferative DR (n = 20). The Dfs were measured on the retinal photographs using a semiautomatic computer-based program.

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/s and 9.3 ± 2.9 and 10.4 ± 3.8 µl/min. The average Df was 1.4276 ± 0.0193. There was no association between the Df and any retinal circulatory parameters of the retinal arterioles. In contrast, we found significant correlations between the Df and the vessel D (r = 0.37, p = 0.0002) and RBF (r = 0.22, p = 0.026) in the retinal venules.

The Df might be associated with changes in the retinal circulation in patients with type 2 DM.