Morphological implications of vascular structures not visualized on optical coherence tomography angiography in retinal vein occlusion

BACKGROUND AND OBJECTIVE: Advanced retinal imaging can improve understanding of retinal vein occlusion (RVO) pathology. The authors aimed to characterize the vascular pathology of RVO on en face optical coherence tomography (OCT) and OCT angiography (OCTA). PATIENT AND METHODS: This was a cross-sectional study including 17 eyes with RVO. The authors identified discordance between vasculature on en face OCT and flow on OCTA, which was correlated with structural findings at the corresponding location on OCT B-scans. RESULTS: Six eyes had vessels that were seen on OCT without flow on OCTA. The most clinically relevant finding was preserved inner retinal layers in areas where the en face OCT showed collaterals that appeared nonperfused on OCTA. CONCLUSIONS: The authors' findings indicate that collaterals can appear on en face OCT without flow on OCTA in RVO and may be associated with relatively preserved inner retinal structures. Clinicians should consider multimodal imaging to evaluate RVO, including both OCT and OCTA.