Freund KB, et al. - Authors ascertained the location of collateral vessels with optical coherence tomography (OCT) angiography imaging. Findings suggested that the course of all collateral vessels associated with retinal vein occlusion was through the deep vascular complex (DVC). A serial arrangement of the SVP and DVC, with venous drainage predominantly coursing through the DVC was supported by the absence of collaterals isolated to the superficial vascular plexus (SVP).

Methods

• Experts conducted an observational retrospective cohort study.
• They studied the collateral vessel formation with OCT angiography (OCTA) in patients with retinal vein occlusion (RVO).
• They conducted this study at 2 retinal practices (Vitreous Retina Macula Consultants of New York and Stein Eye Institute, University of California, Los Angeles), with patient records retrieved from March 2015 to August 2017.
• They completed the data analysis in November 2017.
• They evaluated the collaterals identified with fundus photography and/or fluorescein angiography with OCTA to ascertain their course through the superficial vascular plexus (SVP) and the deep vascular complex (DVC).
• Researchers analyzed the collateral vessel pathways through the SVP and DVC with cross-sectional and en face OCT and OCTA segmentation and color-coded volume renderings prepared from raw OCTA voxel data.

Results

• As per data, from 23 eyes (22 branch and 1 hemispheric retinal vein occlusion ) of 23 patients (mean [SD] age, 73 [11] years), authors identified 101 collateral vessels and analyzed (mean [SD], 4.4 [2.0]; range, 2-9 collateral per eye).
• Findings suggested that on OCTA, the collaterals appeared as curvilinear dilated flow signals that connected veins across the horizontal raphe or veins on opposite sides of an occluded venous segment within the same retinal hemisphere.
• Out of the 101 collaterals analyzed, greater flow signal in the DVC was demonstrated by all, and all had some portion of their course identified within the DVC.
• In the SVP, no exclusive collaterals were found.