Assessing total retinal blood flow in diabetic retinopathy using multiplane en face Doppler optical coherence tomography.

Abstract

To assess total retinal blood flow (TRBF) in diabetic retinopathy (DR) using multiplane <i>en face</i> Doppler optical coherence tomography (OCT). A 70 kHz spectral-domain OCT system scanned a 2×2 mm area centred at the optic disc of the eyes with DR and healthy participants. The multiplane <i>en face</i> Doppler OCT algorithm generated a three-dimensional volumetric data set consisting of 195 en face planes. The TRBF was calculated from the maximum flow values of each branching retinal vein at an optimised <i>en face</i> plane. DR severity was graded according to the international clinical classification system. The generalised linear model method was used to compare flow values between DR groups and the control group. A total of 71 eyes from 71 participants were included. Ten eyes were excluded due to poor image quality. The within-visit repeatability of scans was 4.1% (coefficient of variation). There was no significant difference in the TRBF between the healthy (46.7±10.2 µL/min) and mild/moderate non-proliferative DR (44.9±12.6 µL/min) groups. The TRBF in severe non-proliferative DR (39.1±12.6 µL/min) and proliferative DR (28.9±8.85 µL/min) groups were significantly lower (<i>p</i>=0.04 and <i>p</i><0.0001, respectively) than that of the healthy group. TRBF was correlated with DR disease severity (<i>p</i><0.0001, linear trend test). The novel multiplane <i>en face</i> Doppler OCT method provided reliable measurements of TRBF in DR eyes. This may be a useful tool in understanding the pathophysiology of DR.