Ocular Ischemic Syndrome With Congenital Absence of Internal Carotid Artery

Purpose: This article describes a case of ocular ischemic syndrome (OIS) in a patient with a congenitally absent left internal carotid artery (ICA). Methods: Retrospective case report with anterior-segment and fundus photography, fluorescein angiography (FA), and computerized tomography angiography (CT-A). Results: A 31-year-old-man was found to have neovascularization of the iris (NVI) and angle of the left eye. FA showed capillary nonperfusion in the temporal periphery. He required intravitreal bevacizumab and triamcinolone injections and 2 panretinal photocoagulation treatments for persistent rubeosis and cystoid macular edema. Transient right-eye vision loss prompted CT-A, revealing an absent left ICA. Three years following presentation, FA continued to show delayed arteriovenous flow suggestive of OIS. He has required intravitreal bevacizumab injections every 12 weeks for persistent NVI. Conclusion: Congenitally absent left ICA with resultant cerebrovascular insufficiency is a rare cause of OIS, underscoring the pathophysiological principles of insufficient blood supply to the ophthalmic artery.