Morphological differences between optic disc collaterals and neovascularization on optical coherence tomography angiography

Background: To study morphological features of optic disc venous collaterals (OVCs) and neovascularization of optic disc (NVD) on optical coherence tomography angiography (OCTA). Methods: Patients with OVCs and NVDs secondary to ischemic retinal diseases were prospectively enrolled. Multimodal imaging was performed using color fundus photography, fluorescein angiography (FA), and OCTA. Morphological evaluation of en-face structural OCT, cross-sectional and en-face OCTA was performed. Results: Twenty eyes (20 patients; OVCs: n = 10 and NVD: n = 10) were included. OVCs appeared as small, loopy vessels distinct from surrounding peripapillary capillaries on OCTA in the radial peripapillary capillary frame. NVDs appeared as a mesh of fine caliber, raised vessels best seen in the vitreous slab of OCTA. Flow signals in these vascular alterations correlated well with hyperfluorescence on FA. Conclusions: OCTA provides improved visualization of NVDs and OVCs in ischemic retinal diseases such as diabetic retinopathy and retinal vein occlusions compared to conventional FA.