Transient Monocular Visual Loss

Sudden onset monocular loss of vision usually lasting a few minutes with complete recovery

May be caused by a retinal embolus from the ipsilateral carotid or the heart

Other causes of temporary ocular ischemia are

• Giant cell arteritis

• Hypercoagulable state

• Hyperviscosity

• Severe occlusive carotid disease

Visual loss is characteristically described as a curtain passing vertically across the visual field with complete monocular visual loss lasting a few minutes and a similar curtain effect as the episode passes

More transient episodes of visual loss, lasting only a few seconds to 1 minute, usually recurrent, and affecting one or both eyes, occur in patients with optic disk swelling due to raised intracranial pressure

There is a benign entity of recurrent transient visual loss ascribed to choroidal or retinal vasospasm

Test for diabetes mellitus (fasting serum glucose, hemoglobin A_1C) and hyperlipidemia (fasting serum cholesterol, HDL cholesterol, LDL cholesterol, triglycerides) in all patients

Erythrocyte sedimentation rate and C-reactive protein are usually markedly elevated in giant cell arteritis but one or both may be normal

Consider testing for other types of vasculitis (eg, antinuclear antibody, rheumatoid factor, antineutrophil cytoplasmic antibodies)

In younger patients, consider congenital or acquired hypercoagulable states (thrombophilia)

• Antiphospholipid antibody syndrome (lupus anticoagulant)

• Activated protein C resistance/Factor V Leiden

• Protein C, protein S deficiency

• Antithrombin deficiency

• Hyperprothrombinemia (prothrombin gene G20210A mutation)

• Increased factor VIII activity

• Hyperhomocysteinemia

Obtain duplex ultrasonography of the carotid arteries, ECG, and echocardiography, with transesophageal studies (if necessary), to identify carotid and cardiac sources of emboli

When indicated, obtain CT or MR angiography for internal carotid artery dissection

Emboli are rarely seen on ophthalmoscopy

Calcium channel blockers, such as nifedipine slow-release, 60 mg/day, may be effective in managing the benign variant of transient monocular visual loss

Oral aspirin (at least 75 mg/day) or another antiplatelet drug (eg, dipyridamole, clopidogrel) is used to treat patients with possible embolic transient monocular visual loss until cause can be determined

Consider urgent carotid endarterectomy or possibly angioplasty with stenting in symptomatic patients

• With 70–99% ipsilateral carotid artery stenosis

• Possibly with 50–69% ipsilateral carotid artery stenosis

Anticoagulation is usually required for

• Retinal embolization due to a cardiac arrhythmia, such as atrial fibrillation (thrombophilia)

• A hypercoagulable state

Early referral of all patients with transient monocular visual loss to an ophthalmologist is advisable