Aim To assess total retinal blood flow (TRBF) in diabetic retinopathy (DR) using multiplane en face Doppler optical coherence tomography (OCT).
Methods 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 en face 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 en face 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.
Results 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 (p=0.04 and p<0.0001, respectively) than that of the healthy group. TRBF was correlated with DR disease severity (p<0.0001, linear trend test).
Conclusion The novel multiplane en face Doppler OCT method provided reliable measurements of TRBF in DR eyes. This may be a useful tool in understanding the pathophysiology of DR.
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Contributors Study conception and design were done by ADP, YJ, TSH, DH, OT, DJW and MP. OT and YJ did software development. Data processing was done by ADP, AMH and LL. Data collection and statistical analysis were done by ADP, AMH, LL, XZ and MP. Writing of the manuscript was done by ADP, TSH and AMH. Figures and tables preparation were done by AMH and ADP. Editing and reviewing the manuscript were done by TSH, AMH, YJ and DH. Also, YJ and TSH were guarantors. All authors accepted the final version of the manuscript.
Funding This work was supported by grant DP3 DK104397, R01 EY024544, P30 EY010572 from the National Institutes of Health (Bethesda, Maryland) and by unrestricted departmental funding from Research to Prevent Blindness (New York, New York).
Competing interests Oregon Health & Science University (OHSU), OT, DH and YJ have a significant financial interest in Optovue, a company that may have a commercial interest in the results of this research and technology. OT and DH have a significant financial interest in Carl Zeiss Meditec. These potential conflicts of interest have been reviewed and managed by OHSU.
Ethics approval Institutional Review Board at Oregon Health and Science University.
Provenance and peer review Not commissioned; externally peer reviewed.
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