Collateral Vessels in Branch Retinal Vein Occlusion: Anatomical and functional analysis by Optical Coherence Tomography Angiography

Abstract

Purpose : To anatomically and functionally analyze collateral vessels (CVs) associated with branch retinal vein occlusion (BRVO) using optical coherence tomography angiography (OCTA).

Methods : Medical records and OCTA images of consecutive 29 patients with BRVO were reviewed retrospectively. Distribution of the CV at the 12 months after the onset of BRVO was studied using the RTVue XR Avanti (Optovue Inc). En-face 3×3-mm OCTA images were acquired from nine locations centered on the fovea and used to create a montage image of an 8.1 × 8.1 mm square. CVs were defined as dilated retinal capillaries located between affected veins and healthy veins. Two researchers identified CVs in three separated layers: radial peripapillary capillary (RPC), superficial capillary plexus (SCP), and deep capillary plexus (DCP). The numbers of CVs were evaluated in the four regions: Zone 1, the area within a circle of 3-mm diameter centered on the fovea; Zone 2, the area between the 3-mm circle and its outer circle of 6-mm diameter; Zone 3, the area beyond the 6-mm circle; and the temporal raphe. Main outcome measures were the relationship between the number of CVs in each region and vessel density (VD) in each layer, the presence of the persistent macular edema (ME) at the 12 months, and the number of injections of anti-vascular endothelial growth factor (VEGF) agents.

Results : The number of CV in zone 1 negatively correlated with the VD in the SCP (p=0.0079). The number of CV in RPC, zone 3, and temporal raphe negatively correlated with VD in the DCP (p=0.0034, 0.0017, and 0.036, respectively). In the cases of persistent ME, the number of CVs in zone 1 was significantly (p=0.0156) greater than in the cases of non-persistent ME and positively correlated with the number of anti-VEGF injections (p=0.025).

Conclusions : CVs in BRVO might be associated with capillary dropouts and be considered as the remodeling of retinal capillaries. CVs around the fovea might be associated with persistent ME in BRVO.

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

 

(A) Fluorescein angiography image in major BRVO case. (B, C, D) Magnification of the montage OCTA images in the RPC, SCP and DCP correspond to the yellow squares in A, respectively. Affected veins and healthy veins were painted in purple and in blue. Collateral vessels, which were defined as dilated capillaries between affected and healthy veins, were marked with yellow dashed circle in each layer.