Characteristics of Optical Coherence Tomography Angiography Findings in Chronic Inactive Branch Retinal Vein Occlusion

ABSTRACT

Purpose@#To investigate characteristics of optical coherence tomography angiography (OCTA) findings in chronic inactive branch retinal vein occlusion (BRVO) with quantitative analysis. @*Methods@#The medical records of 48 eyes diagnosed with unilateral ischemic acute BRVO, and without recurrence for 6 months after the acute treatment, were reviewed retrospectively. We manually segmented the abnormal vessels of the superficial and deep capillary plexus (SCP-AV and DCP-AV, respectively) and vascular congestion of DCP (DCP-VC) from 6 × 6 mm2 macular OCTA images and automatically calculated the area, vessel density, and average retinal thickness of each corresponding region. Correlations were analyzed between the OCTA parameters of the segmentation area and the baseline characteristics. @*Results@#The DCP-AV area was always wider than that of the SCP-AV (p < 0.001), with a transitional zone (TZ) between the two areas. About two-thirds of the DCP-VC area was distributed in the TZ. The vessel density of the DCP-VC was higher than that of the normal capillary plexus (all, p < 0.001). The average retinal thickness of the DCP-VC was greater than those of SCP-AV and DCP-AV areas (all, p < 0.001), but not different from the normal capillary plexus. The greater the extent of the DCP-VC distribution under the SCP-AV, the fewer the number of injections required to reach stabilization (r = -0.314, p = 0.030). @*Conclusions@#DCP-VC in chronic inactive BRVO was mainly distributed in the TZ with high vessel density. DCP-VC seems to provide a drainage pathway with minimal resistance against elevated intravenous pressure, which may sustain the anatomical stability of chronic BRVO.