Abstract
Purpose :
Impaired ocular blood flow is associated with major ocular disease, and impaired retinal and peripheral capillary circulation has been observed in glaucoma patients. Nailfold capillaroscopy allows visualization and quantification of peripheral blood flow, while erythrocyte mediated angiography (EMA) permits in vivo determination of retinal capillary blood flow. The purpose of this study is to compare erythrocyte velocities in the retina and the nailfold.
Methods :
We conducted a cross-sectional study of five control subjects to determine nailfold and retinal capillary velocities. Nailfold erythrocyte velocities were measured by tracking blood gap displacement in the capillaries across the image frames, and retinal erythrocyte velocities were determined using a MATLAB script as previously described (Tracey et al., Scientific Reports, 2019). Three second and ten second videos of the nailfold were obtained. ARIA in MATLAB was used to obtain diameter measurements.
Results :
We analyzed five nailfold capillaries in five control patients. The average nailfold capillary velocity was 0.29 ± 0.08 mm/s and the coefficient of variation for velocity and diameter were 0.012 and 0.03 respectively. The average retinal capillary velocity was 0.94±0.03 mm/s, which was significantly different from nailfold capillaries (p<0.01). There was no correlation between retinal and nailfold capillary flowrates (R2 of 0.286, p=0.465).
Conclusions :
We found that retinal capillary velocities are significantly higher than nailfold capillary velocities, consistent with high metabolic rates of the retina. Our nailfold capillary velocities were within range of what is reported in literature. We also present high reproducibility rates of our nailfold velocity and diameter measurements.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.