Ocular ischemic syndrome (OIS) is a rare but vision-threatening condition resulting from severe carotid artery occlusive disease, usually with ≥90% stenosis. It typically affects elderly men with advanced atherosclerosis and may precede stroke. Clinically, OIS presents with progressive or sudden visual loss, ocular pain, and anterior and posterior segment ischemic signs such as iris neovascularization, dilated but non-tortuous veins, arteriolar narrowing, and retinal hemorrhages. Diagnosis relies on fluorescein angiography, indocyanine green angiography, Doppler ultrasound, and magnetic resonance or computed tomography angiography. Differential diagnoses include central retinal vein occlusion and diabetic retinopathy. Management involves systemic treatment of vascular risk factors, ocular therapies to control neovascularization and intraocular pressure, and surgical revascularization procedures such as carotid endarterectomy or stenting. Prognosis is generally poor, especially when iris neovascularization is present, with a high risk of severe visual loss and increased cardiovascular mortality. Early recognition and prompt systemic evaluation are critical to reduce ocular and systemic complications.