Ocular Ischemic Syndrome

Updated: Feb 03, 2023
  • Author: Tahira M Scholle, MD; Chief Editor: Andrew G Lee, MD  more...
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Practice Essentials

Ocular ischemic syndrome (OIS) is a rare eye disease caused by chronic hypoperfusion of the common or internal carotid artery. [1]



Ocular ischemic syndrome encompasses the ocular signs and symptoms that result from chronic vascular insufficiency. Common anterior segment findings include advanced cataract, anterior-chamber cell and flare, and iris neovascularization. Posterior segment signs include narrowed retinal arteries, dilated but nontortuous retinal veins, midperipheral dot-and-blot retinal hemorrhages, cotton-wool spots, and optic nerve/retinal neovascularization. Most patients with ocular ischemic syndrome present with gradual vision loss or pain. [1, 2, 3, 4, 5, 6, 7, 8]



The most common etiology of ocular ischemic syndrome is severe unilateral or bilateral atherosclerotic disease of the internal carotid artery or marked stenosis at the bifurcation of the common carotid artery. It is postulated that the decreased vascular perfusion results in tissue hypoxia and increased ocular ischemia, leading to neovascularization. [4, 9, 10] Ocular ischemic syndrome is more likely to develop in patients with poor collateral circulation between the two internal carotid arteries or between the internal and external carotid arteries. Patients with adequate collateral circulation may not develop ocular ischemic syndrome even if the internal carotid artery is totally occluded. [11]

Patients with ocular ischemic syndrome may show decreased blood flow in the retrobulbar vessels. They may also have reversal of blood flow in the ophthalmic artery because blood is shunted away from the ophthalmic artery and into the lower-resistance intracranial blood vessels. [11]




The incidence of ocular ischemic syndrome is estimated to be 7.5 cases per 1 million population per year but is likely underdiagnosed. [12] Among individuals with carotid occlusive disease, approximately 4% have ocular ischemic syndrome. [13] Ocular ischemic syndrome is bilateral in around 20% of cases.


Patients with ocular ischemic syndrome have a significantly higher rate of vascular disease than the general population; 73% have hypertension, 56% have diabetes, 48% have a history of ischemic heart disease, 27% have had a prior stroke, and 19% have peripheral vascular disease. [14]


Males are affected more frequently than females, by a ratio of approximately 2:1, because of a higher rate of cardiovascular disease in men. [15]


Ocular ischemic syndrome mainly affects elderly patients, with a mean age of 65 years. Ocular ischemic syndrome is uncommon in patients younger than 50 years. [11]



Patients with ocular ischemic syndrome have an overall poor visual prognosis. However, patients with better visual acuity at presentation are more likely to retain good final vision. The presence of iris neovascularization is associated with significantly lower vision, with 97% of cases resulting in a final visual acuity of count fingers or worse. [14, 16, 17]


Patient Education

Smoking cessation, a diet low in fat and sugar, and regular exercise can decrease the rate of vascular disease and potentially lower the likelihood of developing ocular ischemic syndrome.