Tuesday, December 21, 2010

Ocular Ischemic Syndrome

Ocular ischemic syndrome (OIS) refers to the ocular signs and symptoms which result from chronic vascular insufficiency (arterial hypoperfusion) to the eye. Severe ipsilateral or bilateral carotid artery stenosis is the most common cause of ocular ischemic syndrome. The syndrome has been associated with occlusion of the common carotid artery, internal carotid artery, and less frequently the external carotid artery. Other causes include: 1) severe ophthalmic artery occlusion, due to thromboembolism; 2) giant cell arteritis; 3) Takayasu's arteritis.

Common anterior segment signs of this eye condition include advanced cataract, anterior segment inflammation, 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. The presenting symptoms include ocular pain and abrupt or gradual visual loss.

Amaurosis fugax is a form of acute vision loss caused by reduced blood flow to the eye that may be a warning sign of an impending stroke. Consequently, those with transient blurring of vision are advised to urgently seek medical attention for a thorough evaluation of the carotid artery. Those with ocular ischemic syndrome are typically between the ages of 50 and 80; twice as many men than women are affected. More than 90% of those presenting with the condition have vision loss. Patients may report a dull, radiating ache over the eye and eyebrow. Those with ocular ischemic syndrome may also present with a history of other systemic diseases including arterial hypertension, diabetes mellitus, coronary artery disease, previous stroke, and hemodialysis.