Central Retinal Artery Occlusion and Branch Retinal Artery Occlusion

Retinal artery occlusion may be due to embolism or thrombosis.

Emboli may come from any of the following:

• Atherosclerotic plaques

• Endocarditis

• Fat

• Atrial myxoma

Systemic vasculitis, particularly giant cell arteritis, is an important cause of arterial occlusion that requires prompt diagnosis and treatment. Retinal artery occlusion has also been observed in other autoimmune diseases such as systemic lupus erythematosus.

Occlusion can affect a branch of the retinal artery as well as the central retinal artery.

Neovascularization (abnormal new vessel formation) of the retina or iris (rubeosis iridis) with secondary (neovascular) glaucoma occurs in about 15 to 20% of patients within weeks to months after occlusion (1). Vitreous hemorrhage may result from retinal neovascularization.

Risk of stroke is increased after retinal artery occlusion, particularly in the first weeks.

Retinal artery occlusion causes sudden, painless, severe vision loss or visual field defect, usually unilaterally.

The pupil may respond poorly to direct light but constricts briskly when the other eye is illuminated (relative afferent pupillary defect). In acute cases, funduscopy shows a pale, opaque fundus with a red fovea (cherry-red spot). Typically, the arteries are attenuated and may even appear bloodless. An embolus (eg, a cholesterol embolus, called a Hollenhorst plaque) is sometimes visible. If a major branch is occluded rather than the entire artery, fundus abnormalities and vision loss are limited to that sector of the retina.

Patients who have giant cell arteritis are 55 or older and may have a headache, a tender and palpable temporal artery, jaw claudication, fatigue, or a combination.

• Clinical evaluation

Central Retinal Artery Occlusion

Image

Paul Whitten/SCIENCE PHOTO LIBRARY

Once the diagnosis is made, carotid Doppler ultrasonography and echocardiography should be done to identify an embolic source so that further embolization can be prevented.

If giant cell arteritis is suspected (eg, in patients older than 50 years, particularly those who have symptoms such as headache, scalp tenderness, jaw pain, fever, fatigue, and unintended weight loss), erythrocyte sedimentation rate (ESR), C-reactive protein, and platelet count should be done immediately. These tests may not be necessary if an embolic plaque is visible in the central retinal artery.

Because risk of stroke is increased, some centers rapidly evaluate patients similarly to those who have had stroke or transient ischemic attack.

• Reduction of intraocular pressure

If acute thromboembolism is suspected, the patient should be referred immediately to a specialized stroke center because there is an increased risk of other cerebrovascular events.

1). Other treatments have been tried; nonetheless, treatments for retinal artery occlusions rarely improve visual acuity (2). Surgical or laser-mediated embolectomy is available but not commonly done. These treatments are sometimes shown to be effective in small case series, but none have strong evidence to support efficacy.

Patients with occlusion secondary to giant cell arteritis should receive high-dose systemic corticosteroids.

Patients with a branch artery occlusion may maintain good to fair vision, but with central artery occlusion, vision loss is often profound, even with treatment. Once retinal infarction occurs (as quickly as 90 minutes after the occlusion [1]), vision loss is permanent.

If underlying giant cell arteritis is diagnosed and treated promptly, the vision in the uninvolved eye can often be protected and some vision may be recovered in the affected eye.