Characteristics of Retinal Blood Flow, Velocity and Vessel Diameter of eyes with Branch Retinal Vein Occlusion as revealed by Doppler Optical Coherence Tomography Flowmeter

Abstract

Purpose : Doppler optical coherence tomography flowmeter (DOCT flowmeter) instantaneously (< 3sec) analyses rheological properties of retinal blood vessels, including measurement of absolute retinal blood flow (RBF), blood velocity and vessel diameter. Herewith, we report the characteristics of RBF, blood velocity and vessel diameter on the occluded and the non-occluded vein in eyes with branch retinal vein occlusion (BRVO) and the vein in healthy eyes as measured by DOCT flowmeter.

Methods : Twenty patients with unilateral BRVO were enrolled. Using DOCT flowmeter, RBF, blood velocity, and diameter were measured from 3 veins, i.e., 1. an occlude vein, 2. a non-occluded vein in BRVO eyes and 3. a vein in the fellow eye (non-affected vein), in each patient. Paired t-test was employed to compare the parameters of DOCT flowmeter and Pearson chi-square test were used to test the association between RBF and vessel diameter. Bonferroni corrected P < 0.05 was considered statistically significant.

Results : Mean patient age was 65.2 ± 9.8 yrs. Mean systolic and diastolic blood pressure were 141.6 ± 19.8 mmHg and 80.1 ± 11.9 mmHg, respectively. The RBF in the occluded veins (4.7 ± 3.5 µL/min) was lower than that in the non-occluded veins (11.0 ± 5.0 µL/min) and that of the fellow eyes (8.9 ± 3.4 µL/min) (p < 0.01). There were no significant differences in the blood velocity among the three types of veins. (p > 0.1). The diameter in the occluded vein (96.1 ± 25.5 µm) was smaller than the one in the non-occluded (130.7 ± 24.1 µm) and the healthy veins (123.3 ± 15.0 µm) (p< 0.01). Additionally, the RBF was correlated with the diameter in the occluded vein (p< 0.05, r=0.46).

Conclusions : DOCT, for the first time in BRVO patients, disclosed that the RBF of the occluded veins was significantly lower than the other veins and the RBF in the occluded vein was correlated with the vessel diameter, suggesting that RBF reduction in the occluded veins of BRVO depends on vasoconstriction of vessels but not on decrease in blood velocity.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.