Amaurosis Fugax

Key Points at a Glance

Key Points of This Disease

• Amaurosis fugax is a condition in which vision in one eye decreases for seconds to minutes and then fully recovers.
• The most common cause is transient occlusion of the ophthalmic artery or retinal artery due to thromboembolism from an atheroma at the bifurcation of the internal and external carotid arteries.
• It is considered a form of transient ischemic attack (TIA) and can be an imminent warning sign of stroke.
• Symptoms have often resolved by the time of consultation, so a detailed history and imaging/vascular assessment are essential.
• Because carotid artery stenosis is frequently associated, vascular evaluation such as carotid ultrasound and MRA is mandatory.
• Antiplatelet therapy and carotid endarterectomy for high-grade stenosis are the mainstays of standard treatment.
• If giant cell arteritis (GCA) is the cause, urgent high-dose steroid therapy is required.

1. What is Amaurosis Fugax?

Amaurosis fugax (AF) is a condition in which vision in one eye transiently decreases and recovers within seconds to minutes (sometimes hours).

It is broadly divided into transient monocular vision loss (TMVL) and transient binocular vision loss (TBVL), with monocular being the most common. Ischemic amaurosis fugax is considered a form of transient ischemic attack (TIA) ^1,3).

Clinically, it is an urgent condition that can be a precursor to stroke, requiring prompt stroke workup after onset ^1,3). Even in modern cohorts, cases evaluated as transient retinal ischemia undergo detailed examination and secondary prevention considering recurrent events and cerebral ischemic risk ²⁾.

When amaurosis fugax occurs, it is important to note that carotid artery stenosis is frequently associated.

Q What is the relationship between amaurosis fugax and stroke?

A

Amaurosis fugax is considered a form of TIA and can be an impending precursor to stroke ^1,3). After onset, emergency evaluation including a stroke center is recommended.

2. Main Symptoms and Clinical Findings

Subjective Symptoms

• “Curtain falling in front of the eye”-like visual disturbance: Characteristic negative symptom where part or all of the visual field in one eye suddenly becomes dark.
• Duration: Usually seconds to minutes, but may last several hours. In all cases, vision returns to normal afterward.
• Spontaneous recovery: Symptoms disappear spontaneously and are often gone by the time of examination. Therefore, history taking is key to diagnosis.
• Associated symptoms (internal carotid artery system TIA): May include weakness or paralysis of limbs/face, sensory disturbance, dysarthria, and aphasia (left side).
• Vertebrobasilar system symptoms: May include dizziness, numbness of body/face, dysarthria, and diplopia.
• Positive symptoms: Even if positive symptoms such as photopsia are present, ischemic etiology is not ruled out.

Clinical Findings (Findings Confirmed by Physician Examination)

Most patients show no abnormalities on ophthalmic examination, but the following findings may be observed.

• Hollenhorst plaque: Cholesterol emboli in retinal vessels. Evidence of emboli from carotid artery lesions.
• Ocular ischemic signs: Dilatation of retinal veins, patchy hemorrhages in the mid-peripheral retina, neovascularization of the iris and retina.
• Ocular steal phenomenon: During chronic cerebral ischemia, the ophthalmic artery becomes a collateral pathway from the face to the brain, worsening ocular ischemia.
• Soft exudates and bright plaques: Fundus findings suggesting emboli release. Attention to complications in the cranial nervous system is required.

Q How can transient monocular vision loss (amaurosis fugax) and scintillating scotoma be differentiated?

A

Both conditions have similar symptoms but can be distinguished by the following points. Transient monocular vision loss is monocular, negative symptoms (visual field darkening), duration 1–5 minutes, and may be accompanied by dysarthria or hemiparesis. Scintillating scotoma is binocular, positive symptoms (zigzag lights), duration 20–30 minutes, and often followed by throbbing headache. The causes also differ: transient monocular vision loss is due to stenosis or occlusion of the internal carotid artery, while scintillating scotoma is due to cortical spreading depression or vasospasm.

3. Causes and Risk Factors

The causes of TMVL can be classified into vascular, neurological, and ophthalmic categories.

Vascular (most common):

• Internal carotid artery disease (most important): Thrombi detach from atheroma at the bifurcation of the internal and external carotid arteries, transiently occluding the ophthalmic artery or retinal artery branches.
• Cardiogenic embolism: Thrombi from the heart due to arrhythmia (atrial fibrillation) embolize.
• Giant cell arteritis (GCA): Vasculitis can be a cause in elderly patients. Many have a history of transient monocular vision loss.
• Cardiac myxoma: Rare, but depending on tumor size, can cause embolism anywhere from the aorta to the retinal arteries.
• Vascular anatomical variants: Patients with a persistent primitive hypoglossal artery (PPHA) may present with symptoms of both anterior and posterior circulation. ⁴⁾

Neurological:

• Retinal migraine

Ophthalmic:

• Papilledema, optic disc drusen, intermittent angle-closure glaucoma

Causes of TBVL: Vertebrobasilar ischemia, migraine, occipital lobe epilepsy, posterior reversible encephalopathy syndrome (PRES).

Risk factors: Carotid artery stenosis (most important), diabetes, hypertension, advanced age, hyperlipidemia, smoking, atrial fibrillation, hypercoagulable state, myeloproliferative disorders^1,3).

Differential diagnosis in younger patients: In relatively young patients presenting with amaurosis fugax or neovascular glaucoma, differential diagnosis from aortic syndrome (Takayasu arteritis) is necessary.

Prevention and Daily Care

Control of hypertension, diabetes, and dyslipidemia is important for prevention. If you experience vision loss in one eye, even transiently, promptly visit an ophthalmologist and a stroke center even if symptoms resolve. Smoking is a major risk factor for carotid artery disease, and smoking cessation is strongly recommended.

4. Diagnosis and Examination Methods

Medical History Taking

Symptoms often resolve by the time of consultation, so accurate history taking is crucial. Items to confirm are as follows:

• Whether vision loss was monocular or binocular (whether the patient covered one eye during the episode)
• Duration, triggers, completeness of recovery, and recurrence of episodes
• Presence of giant cell arteritis symptoms (jaw claudication, headache, scalp tenderness) – especially important in elderly patients
• Vascular risk factors, history of heart disease, valvular disease, atrial fibrillation

Physical Examination and Ophthalmic Tests

A complete ophthalmic examination (check for Hollenhorst plaque, angle-closure glaucoma) is necessary. Check for temporal artery tenderness and carotid bruits. For evaluation of ocular ischemia, electroretinography (ERG) and fluorescein angiography (FAG) are used; if choroidal or retinal ischemia is present, consider retinal photocoagulation.

Blood Tests and Imaging

Imaging procedure:

1. CT and MRI (diffusion-weighted imaging: DWI) are used to assess the presence and extent of cerebral infarction.
2. MRA and carotid artery ultrasound (Doppler) evaluate carotid artery occlusion or stenosis.
3. If necessary, carotid angiography is performed for definitive diagnosis.

• Inflammatory markers (ESR, CRP): Performed in elderly patients to rule out giant cell arteritis.
• Cardiac evaluation: Echocardiography (TTE/TEE) and electrocardiography to search for cardioembolic sources.
• Electroencephalography (EEG): Indicated in TBVL when seizure is suspected from history.

If transient ischemic attack occurs, brain diffusion MRI may show cerebral infarction in the acute phase, and many cases progress to cerebral infarction after several months.

Differential Diagnosis and Comparison Table

Care should be taken to differentiate from the following conditions: papilledema, arteritic ischemic optic neuropathy, impending central retinal vein occlusion, glaucoma, retinal vasospasm, and intermittent vitreous hemorrhage.

The differentiation between amaurosis fugax and scintillating scotoma is shown below.

Differentiating Feature	Amaurosis Fugax	Scintillating Scotoma
Ocular involvement	Monocular	Binocular, homonymous
Nature of symptoms	Negative symptoms (darkening)	Positive symptoms (flashing lights)
Duration	1–5 minutes (within 10 minutes)	20–30 minutes (within 60 minutes)
Associated symptoms	Dysarthria, hemiparesis, etc.	Pulsatile headache, nausea

Q If amaurosis fugax is suspected, what tests should be performed?

A

First, CT or MRI (DWI) is performed to check for cerebral infarction, followed by carotid ultrasound or MRA to evaluate carotid artery stenosis^1,3). In elderly patients, ESR and CRP are also used to assess giant cell arteritis. If a cardioembolic source such as atrial fibrillation is suspected, echocardiography and electrocardiography are performed¹⁾.

5. Standard treatment

The treatment strategy depends on the suspected etiology. In many cases, the primary physician refers the patient to a vascular surgeon or other specialist outside ophthalmology, but the ophthalmologist must also evaluate the cause of transient vision loss and the degree of ocular ischemia, and continue to regularly follow up on visual acuity, visual field, and fundus findings even after transferring the primary management of the patient to a neurosurgeon or vascular surgeon.

Antithrombotic therapy

Antiplatelet therapy is used to prevent cerebral infarction¹⁾.

Drug	Dose	Recommendation Grade
Aspirin	75–150 mg/day	Grade A
Clopidogrel	75 mg/day	Grade A
Cilostazol	200 mg/day	Grade B
Ticlopidine	200 mg/day	Grade B

Low-dose aspirin or prostaglandin-related drugs may be prescribed to avoid thromboembolism. For atrial fibrillation, anticoagulation therapy such as warfarin is used.

Surgical Treatment (Carotid Artery Lesions)

For severe internal carotid artery stenosis, the following treatments are performed.

• Carotid Endarterectomy (CEA): Surgery to surgically remove plaque from the intima.
• Carotid Artery Stenting (CAS): Placement of a stent in the stenotic area using a catheter.

Other invasive treatments include stellate ganglion block and superficial temporal artery-middle cerebral artery anastomosis.

If Giant Cell Arteritis is Suspected

If giant cell arteritis is suspected, empirical steroid therapy is initiated, along with ESR/CRP confirmation and temporal artery biopsy. High-dose intravenous corticosteroid therapy 1 g/day for 3–5 days is given, followed by oral steroid therapy 1 mg/kg/day. The dose is slowly tapered over at least 4–6 months (some cases require continuation for 1 year). Alternate-day steroid dosing is not recommended.

Management of Ocular Ischemic Syndrome

Fluorescein angiography should be performed, and retinal photocoagulation should be applied to ischemic areas.

Cardiac Myxoma

Surgical resection is required. Long-term monitoring after resection is essential.

Precautions in Treatment

Amaurosis fugax is a form of TIA and carries a high risk of progression to stroke ^1,3). Even if transient, a stroke workup should be performed promptly after onset. Ophthalmologists are required to regularly follow up visual acuity, visual field, and fundus findings even after referring the patient’s primary care to a vascular surgeon, etc.

Q What medications are used to prevent recurrence of amaurosis fugax?

A

For prevention of cerebral infarction, antiplatelet drugs such as aspirin (75–150 mg/day) or clopidogrel (75 mg/day) are first-line therapy (Grade A). If atrial fibrillation is the cause, anticoagulation therapy with warfarin or similar agents is indicated. For severe carotid artery stenosis, carotid endarterectomy or carotid artery stenting may be considered.

6. Pathophysiology and Detailed Mechanisms

The common mechanism of TMVL is hypoperfusion of the retina or optic nerve. This hypoperfusion can result from hypotension, thrombosis, embolism, arteritis, or vasospasm.

Embolic mechanism (most common): An embolus detaches from a carotid atheroma and transiently occludes the ophthalmic artery, central retinal artery, or a branch of the retinal artery.

Cardiogenic embolism: Thrombi from conditions such as atrial fibrillation embolize. Emboli from cardiac myxoma can cause occlusion at any site from the aorta to the retinal arteries. If not treated promptly, cardiogenic embolic events can lead to permanent vision loss, stroke, or death.

Vasculitis (GCA): Inflammatory occlusion of the short posterior ciliary arteries reduces perfusion to the optic nerve via one or more of these arteries.

Ocular ischemic syndrome: Persistent severe internal carotid artery occlusion can lead to retinal artery occlusion, ischemic optic neuropathy, and neovascular glaucoma.

Ocular steal phenomenon: In chronic cerebral ischemia, the ophthalmic artery becomes a collateral pathway from the face to the brain, further exacerbating ocular ischemia.

Mechanism of TBVL: It may result from bilateral hypoperfusion (e.g., vertebrobasilar ischemia) or suggest lesions anterior to the optic chiasm, at the chiasm, or posterior to the chiasm.

Effect of vascular anatomical variants: In patients with a persistent primitive hypoglossal artery (PPHA), the internal carotid artery serves as the main supply to the posterior circulation, so carotid lesions can cause symptoms in both the anterior and posterior circulations. ⁴⁾

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7. Latest Research and Future Perspectives (Investigational Reports)

For patients: Please read this

The following information is currently under investigation or in clinical trials and is not standard treatment available at general hospitals. It is reference information for professionals regarding future medical developments.

CEA in Patients with Vascular Anatomical Variants

In patients with a rare congenital vascular anomaly called persistent primitive hypoglossal artery (PPHA) (incidence 0.027–0.26%), carotid lesions can cause symptoms in both the anterior and posterior circulations, making preoperative anatomical imaging essential.

Telianidis et al. (2023) reported a case of an 83-year-old man with transient monocular vision loss in the left eye (left internal carotid artery stenosis >90%, with PPHA) who underwent CEA under local anesthesia. ⁴⁾ Although intraoperative shunting is reportedly used in 66% of CEA cases with PPHA, in this case, neurological function was continuously monitored under local anesthesia and conscious sedation, and shunting was avoided. During cross-clamping, permissive hypertension targeting a systolic blood pressure of 190–200 mmHg was applied, and the surgery was completed without neurological deterioration.

CEA under local anesthesia, compared to general anesthesia, shows no difference in postoperative stroke, myocardial infarction, or mortality rates, but has been associated with reduced perioperative complications, shorter operative time, and shorter hospital stay.

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8. References

1. Mbonde AA, Mamuya FA, Mohamed Q, Phan K, Vingrys AJ, Lim LL. Current Guidelines on Management of Amaurosis Fugax and Transient Ischemic Attacks. Asia Pac J Ophthalmol (Phila). 2022;11(2):168-176. PMID: 35213421.
2. Martinez-Viguera A, Xuclà-Ferrarons T, Collet R, et al. Clinical characteristics and outcome of amaurosis fugax due to transient retinal ischemia: Results from a contemporary cohort. J Stroke Cerebrovasc Dis. 2023;32(11):107335. PMID: 37748428.
3. The Amaurosis Fugax Study Group. Current management of amaurosis fugax. Stroke. 1990;21(2):201-8. PMID: 2406992.
4. Telianidis S, Westcott MJ, Ironfield CM, Sanders LM. Case of Amaurosis Fugax in the Setting of a Persistent Primitive Hypoglossal Artery Requiring Carotid Endarterectomy with Regional Anesthesia. Am J Case Rep. 2023;24:e939450. PMID: 37025053.