Depth-Resolved Imaging of Papillary Vitreoretinal Neovascularization: OCT-Angiography Assessment in Ocular Ischemic Syndrome
Ocular ischemic syndrome results from compromised blood flow to the eye and is usually related to proximal large vessel disease. Affected patients may show rubeosis, neovascular glaucoma, arteriolar attenuation, dilated but not tortuous veins, intraretinal hemorrhages, macular edema, neovascularization of the optic disk and retina, and collateral vessels at the optic nerve head.1 A 67-year-old man complained of visual loss in his left eye. Best-corrected visual acuity was 20/200. The optic nerve head showed a fine neovascular network (Figure 1), veins were dilated but not tortuous, and arteriolar attenuation was also visible. Fluorescein angiography (Figure 2) revealed a prolonged arm-to-eye time, a delayed arterial–venous perfusion, and an abnormal vascular network of the optic disk corresponding to a leaking neovascularization radiating toward the nasal periphery in the late phases. Ocular ischemic syndrome diagnosis was confirmed by carotid doppler ultrasonography that showed a decreased blood flow to the eye, as a result of narrowing of the ophthalmic artery.2 Optical coherence tomography angiography (OCT-A) was performed using a Spectralis OCT-A prototype (Heidelberg Engineering, Heidelberg, Germany) with a 15 × 10° volume scan (261 B-scans) centered on the optic disk. The OCT-angiograms were analyzed with multiple 80-μm-thick slabs, manually fine-tuned from the retinal pigment epithelium to the vitreous cavity.3 The multilayered OCT-A assessment separately showed the origin of new vessels from the deep papillary vasculature and the presence of collateral “shunting” vessels above the optic disk (Figure 3); moreover, the proliferation of epiretinal new vessels (Figure 4) and their radiation into the vitreous cavity (Figure 5) were highlighted. Although fluorescein angiography gives useful information on the presence and leaking activity of neovascularizations, OCT-A provides an in vivo definition of the morphology of new vessels.4,5 This depth-resolved assessment might be useful to analyze the anatomical and topographical relationships of neovascularizations with different retinal structures and their changes after intravitreal or laser treatments.