Deterioration of Retinal Blood Flow Parameters in Branch Retinal Vein Occlusion Measured by Doppler Optical Coherence Tomography Flowmeter

Abstract

Background: Doppler optical coherence tomography (DOCT) flowmeter can be used to measure retinal blood flow (RBF) parameters, including vessel diameter, blood velocity, and the absolute value of RBF within 2.0 s. We investigated the RBF parameters in eyes with branch retinal vein occlusion (BRVO) using a DOCT flowmeter. Methods: Seventeen patients with unilateral BRVO were enrolled. All subjects underwent comprehensive ophthalmologic examinations. The RBF parameters were assessed from three veins, i.e., (1) an occluded vein, (2) a non-occluded vein in the BRVO eyes, and (3) an equivalent (superior or inferior) vein in the fellow eye (non-affected vein), using prototype DOCT flowmeter (Topcon, Tokyo, Japan). Moreover, the correlation between RBF parameters and the best corrected visual acuity (BCVA) was examined. We investigated the correlation between (1) the RBF parameters and the time from the initial visit, (2) the RBF parameters and the time from the last injection, and (3) the RBF parameters and the number of anti-vascular endothelial growth factor injections (VEGF). Results: The diameter of the occluded vein (95.9 ± 24.7 µm) was smaller than that of the non-occluded vein (127.9 ± 23.7 µm) and that of the healthy veins (116.4 ± 13.9 µm). The RBF was lower in the occluded veins (4.7 ± 3.7 µL/min) than that in the non-occluded veins (10.3 ± 5.1 µL/min; p < 0.01) and in the fellow eyes (8.6 ± 4.0 µL/min; p = 0.013). In contrast, the blood velocity was not significantly different among the three types of veins. BCVA was correlated with the diameter of the occluded vein (ρ = 0.711, p = 0.001) but not with the RBF and blood velocity. The time from the initial visit, the time from the last injection, and the total number of anti-VEGF injections were not associated with any RBF parameters on the occluded vein. Conclusions: The RBF was significantly lower in the occluded veins than that in the other veins, and the diameter of the occluded vein was significantly smaller than that of the other veins in patients with BRVO. However, neither the time from the initial visit, nor the time from the last injection, nor the number of anti-VEGF injections were correlated with the RBF parameters on the occluded vein.

Quantitative Assessment Parameters of Peripapillary Regions with Branch Retinal Vein Occlusion by Using Optical Coherence Tomography Angiography

“…In the research of Takahashi et al, the diameter of the occluded vein in BRVO patients at half-disc diameter away from the optic disc was smaller than healthy veins. And, the retinal blood flow in the occluded vein was lower than in the healthy veins [ 14 ]. We found that the density of the larger blood vessels in the whole image and peripapillary was higher compared to that of the fellow eyes.…”

Hypothetical proposal for the course of retinal blood vessels in the posterior pole—description and its clinical implications

“…These physical laws, in addition to the cellular composition and neurovascular control of the retinal blood vessels, help to explain the maintenance of steady vascular flow and pressure gradients within the major and minor branches, as well as in the capillary bed [16]. Dysregulation of one or more of these elements-part of the Virchow triad-is a primary element in the pathogenesis of retinal vascular occlusions, particularly BRVO [17]. BRVO, the most common retinal vascular disorder after diabetic retinopathy, has a varied presentation and natural course [18,19].…”