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Key Features

  • 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 A1C) 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

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