Amaurosis Fugax

• Joseph S. Kass, M.D., J.D
• Tzu-Ching (Teddy) Wu, M.D., M.P.H.

 Basic Information

Definition

Amaurosis fugax is a temporary loss of monocular vision caused by transient retinal ischemia.

ICD-10CM CODES
G45.3	Amaurosis fugax

Epidemiology & Demographics

Incidence (In U.S.)

An uncommon but important presentation of carotid artery disease

Peak Incidence

Approximately 55 yr

Physical Findings & Clinical Presentation

1. •

   Onset is sudden, typically lasting seconds to minutes, and often accompanied by scotomas such as a shade or curtain being pulled over the front of the eye (usually downward).

2. •

   Vision loss can be complete, hemianopic, or quadrantic.

3. •

   Acute stage: cholesterol emboli may be seen in retinal artery (Hollenhorst plaque); carotid bruits or other evidence of generalized atherosclerosis.

4. •

   If embolus is cardiac in origin, atrial fibrillation is often present.

Etiology

1. •

   Usually embolic from the internal carotid artery or the heart

2. •

   Giant cell arteritis causing inflammation of retinal arteries

3. •

   Hyperviscosity syndromes, such as sickle cell disease, which causes ischemia in the vascular territory of the ophthalmic artery

4. •

   Hypercoagulable states

5. •

   Reversible cerebral vasoconstriction syndrome

Diagnosis

Differential Diagnosis

1. •

   Retinal migraine: in contrast to amaurosis, the onset of visual loss develops more slowly, usually over 15 to 20 min.

2. •

   Transient visual obscurations occur in the setting of papilledema; intermittent rises in intracranial pressure briefly compromise optic disc perfusion and cause transient visual loss lasting 1 to 2 seconds. The episodes may be binocular. If the visual loss persists at the time of evaluation (i.e., vision has not yet recovered), then the differential diagnosis should be broadened to include:

   1. 1.

      Anterior ischemic optic neuropathy: arteritic (classically GCA) or nonarteritic

   2. 2.

      Central retinal vein occlusion

Workup

1. •

   Workup should focus on embolic sources, but GCA should always be considered.

2. •

   Careful examination of retina; embolus may be visible and confirm the diagnosis (Fig. 1).

   

3. •

   Auscultation of arteries for carotid bruits.

4. •

   Examination of all pulses and for temporal artery tenderness.

5. •

   Inquire about symptoms of GCA (scalp tenderness, headache, fever, jaw claudication).

6. •

   Examine for signs of hemispheric stroke resulting from intracranial aneurysm (contralateral limb and facial weakness or sensory loss, aphasia, etc.).

Laboratory Tests

1. •

   Complete blood count with erythrocyte sedimentation rate and C-reactive protein.

2. •

   Serum chemistries, including lipid profile.

3. •

   Cardiac enzymes and ECG.

4. •

   Hypercoagulable workup is discretionary based on younger age and history.

Imaging Studies

1. •

   Carotid Doppler imaging or MR or CT angiography as indicated.

2. •

   Transthoracic echocardiography is indicated to screen for sources of emboli in patients with evidence of heart disease and in patients without an evident source for transient neurologic deficit. Transesophageal echocardiography is more sensitive for detecting cardiac sources of emboli (ventricular mural thrombus, atrial appendage, patent foramen ovale, aortic arch).

3. •

   MRI of the brain with diffusion-weighted imaging to look for infarcts, especially those presenting with focal neurologic disturbances.

Treatment

Nonpharmacologic Therapy

1. •

   Diet (decrease saturated fatty acids and high-cholesterol foods)

2. •

   Exercise

3. •

   Cessation of tobacco use

Acute General Rx

1. •

   Investigate as an emergency.

2. •

   Aspirin if etiology is presumed embolic.

3. •

   If GCA is suspected, start prednisone and refer for temporal artery biopsy within 48 hr (see “Giant Cell Arteritis” in Section I).

Chronic Rx

1. •

   Reduce risks by carotid endarterectomy if stenosis >50%. Carotid stenting may be performed in high-risk surgical candidates.

2. •

   Control hypertension and manage vascular risk factors.

3. •

   Antiplatelet therapy.

4. •

   Statin.

Disposition

Among patients with >50% carotid stenosis who do not undergo carotid endarterectomy, those who present with transient monocular blindness have an approximate 10% risk of stroke within 3 years compared with an approximate 20% risk in patients who present with a hemispheric transient ischemic attack (TIA).

Referral

1. •

   As with any TIA, emergent inpatient workup in a hospital that is a certified stroke center, if possible.

2. •

   If significant carotid stenosis, consider either carotid endarterectomy or carotid stenting for the following:

   1. 1.

      Ipsilateral high-grade (≥70%) stenosis, but consider for ipsilateral stenosis of 50% to 69%.

   2. 2.

      Multiple TIAs despite medical therapy in the setting of high-grade or ulcerative disease

Pearls & Considerations

1. •

   Cholesterol emboli in retinal arteries on funduscopy confirm the diagnosis.

2. •

   Recognize that transient visual loss has multiple other causes.

3. •

   Refer to emergent evaluation like any other transient ischemic attack.

Related Content

1. Amaurosis Fugax (Patient Information)

2. Carotid Stenosis (Related Key Topic)

3. Giant Cell Arteritis (Related Key Topic)

4. Transient Ischemic Attack (Related Key Topic)