Posterior ischemic optic neuropathy as a complication of Moyamoya syndrome in a 36-year-old male with sickle cell anemia

Purpose. To describe a unique case of posterior ischemic optic neuropathy (PION) in a 36-year-old man with sickle cell disease (SCD) and Moyamoya syndrome (MMS), highlighting the rare and complex interaction of these conditions and their implications in ocular ischemic events. Case Report. A North African male with homozygous SCD presented with sudden, painless diminution of vision in his left eye, two months before consulting in our department. On examination, his visual acuity was preserved in the right eye but limited to counting fingers at one meter in the left eye. A significant left relative afferent pupillary defect was noted. Funduscopic examination and Fluorescein angiography showed signs of proliferative sickle cell retinopathy, with optic disc atrophy in the left eye. Computed tomography angiography and magnetic resonance angiography of the brain confirmed MMS with stenosis of the internal carotid artery and Moyamoya vessel formation, as well as optic nerve atrophy. No recovery in visual acuity was observed one year later. Conclusion. This case is notable for the unusual coexistence of SCD, MMS, and PION in the same patient. It also highlights the complexity of managing coexisting SCD and MMS, as both conditions amplify the risk of cerebral and ocular ischemic events, leading to irreversible vision loss. Multidisciplinary care is essential to monitor and address the diverse manifestations of these overlapping conditions and prevent severe outcomes.