Foveolar choroidal hemodynamics in proliferative diabetic retinopathy

We studied the choroidal circulation in patients with proliferative diabetic retinopathy (PDR) to assess whether choroidal hemodynamic abnormalities may exist in PDR.

Eighteen eyes of 18 patients with PDR and high-risk characteristics for visual loss were included in this study. Mean duration of diabetes was 20 +/- 9 years (mean +/- SD), hemoglobin A1c was 8.9 +/- 2.3%, and blood glucose at the time of blood flow measurement was 188 +/- 90 mg/dl. Choroidal circulatory parameters obtained in these patients were compared to those of 35 eyes of 35 age and blood pressure matched, healthy controls using a Wilcoxon rank sum test. Laser Doppler flowmetry (Oculix) was used to calculate relative choroidal blood velocity (Chvel), volume (Chvol), and flow (Chflow) in the center of the foveola.

No significant differences in average age, mean blood pressure (BPm), or perfusion pressure (PP) were observed between diabetic patients and control subjects. In diabetic patients, Chvol was 0.29 +/- 0.08 (mean +/- 1 SD) arbitrary units (AU); this value was 15% lower than that of control subjects, 0.34 +/- 0.10 AU (p = 0.04). In contrast, average Chvel was not significantly different between subjects with PDR (0.39 +/- 0.07 AU) and control subjects (0.41 +/- 0.07 AU). The average Chflow in subjects with PDR (9.4 +/- 2.9 AU) was 27% lower than that of control subjects (12.8 +/- 4.2 AU; p = 0.003). No significant correlation was detected between the circulatory measurements and age, BPm, or PP. There was a statistically significant negative correlation between duration of diabetes and Chvel (R = -0.55; p = 0.03).

Our results suggest that Chvol and Chflow are significantly reduced in patients with PDR.