Transient Monocular Visual Loss

Key Features

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

Clinical Findings

• 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 (see below)

  • 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

Diagnosis

• 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

Treatment

• 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