Etiopathogenesis of ocular ischemic syndrome

Ocular ischemic syndrome (OIS) is a collection of symptoms of carotid and ophthalmic artery disease of common genesis accompanied by ischemia of eyeball membranes. Specifically, the intraocular blood flow becomes impaired due to inflow reduction or arrest, while the venous outflow remains patent. Causes of OIS include arterial hypertension, atherosclerosis, diabetes, aortoarteritis and other vascular diseases. Clinical features depend on the extent, nature, and site of vascular involvement as well as the concurrent pathology. The process is unilateral and both the anterior and posterior eye segments become affected. Symptoms may vary in severity - from acute to indistinct, and thus, can be neglected or misdiagnosed. Acute course is characterized by sudden onset and sharp deterioration of vision. Clinical manifestations are the following: amaurosis fugax, acute ischemic optic neuropathy, central retinal artery and branch retinal artery occlusions, Amalric syndrome, and ischemic oculopathy. Chronic OIS is notable for slowly progressive visual loss and diverse manifestations, such as chronic ischemic optic neuropathy, chronic ischemic retinopathy, chronic ischemic choroidopathy, and open-angle glaucoma with anterior segment ischemia. To date, there is no general consensus on the nature of this disorder, which complicates its diagnosis and treatment and necessitates a multidisciplinary approach.