Retinal ischemia and embolism. Etiologies and outcomes based on a prospective study

To identify the most likely mechanisms of retinal ischemia and embolism in a hospital-referred population, and to determine the frequency of recurrent vascular events during the 3-month period following initial presentation.

Consecutive patients presenting to 2 tertiary medical centers and their outpatient clinics were prospectively enrolled over a 22-month period. Eligible patients presented with histories of transient or permanent monocular visual loss, or had evidence of asymptomatic retinal embolism on routine ophthalmological examination. They underwent a rapid and standardized evaluation that included imaging studies as well as blood tests, and follow-up was obtained at 1 and 3 months.

Seventy-seven patients were enrolled. Enrollment diagnoses consisted of amaurosis fugax (n = 32), asymptomatic retinal embolism (n = 34), and central or branch retinal artery occlusion (n = 11). Eight different presumed etiologies of retinal artery distribution embolism or hypoperfusion were identified. Extracranial internal carotid artery occlusion or more than 50% stenosis was observed in 17/77 (22.1%) cases, making it the largest etiologic subgroup. Uncommon but treatable conditions were identified in 8/77 (10.4%) patients, and an etiologic diagnosis could not be made in 35/77 (45.5%) patients. Recurrent events occurred in, respectively, 14/77 (18.2%) and 6/73 (8.2%) patients at the 1- and 3-month follow-ups. They included 2 infarcts and 2 deaths; ischemic events of the retina were more common than those involving the brain.

Severe stenosis of the extracranial internal carotid artery is the most common identified condition associated with retinal ischemia and embolism, but a variety of other, potentially treatable, conditions can be diagnosed if appropriate and specific evaluations are conducted. The frequency of recurrent vascular ischemic events is highest during the 1st month of follow-up and decreases during the 2nd and 3rd months. Recurrences range from relatively innocuous episodes of amaurosis fugax to vascular death.