Amaurosis fugax …

Adrian Marchidann MD

Stroke & Vascular Disorders

Updated 07.24.2024
Released 04.13.1995
Expires For CME 07.24.2027

Amaurosis fugax

Author: Adrian Marchidann MD

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Editor: Steven R Levine MD

Amaurosis fugax

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Introduction

Overview

Amaurosis fugax, or transient vision loss, has many causes, some of which may lead to blindness or stroke. The author reviews the current literature concerning the potential pathophysiologic mechanisms, diagnostic testing, and treatment strategies. The section on the prevention of stroke in patients with carotid steno-occlusive disease has been expanded to reflect the results of several completed clinical trials.

Key points

	• Amaurosis fugax is transient monocular or binocular vision loss due to retinal artery ischemia.
	• Amaurosis fugax is a medical emergency requiring prompt evaluation and treatment.
	• The risk of stroke following amaurosis fugax is lower than after an ischemic stroke.
	• Morphology of a vulnerable plaque may better reflect the risk of stroke than severity of carotid artery stenosis.
	• In the absence of internal carotid artery atherosclerosis, vasospasm of internal carotid and ophthalmic arteries or venous abnormalities may be responsible for amaurosis fugax.
	• Revascularization of symptomatic carotid artery stenosis may prevent ischemic stroke; the optimal timing of the procedure is between days 3 and 14 after the ischemic event.
	• Stenting and carotid endarterectomy of eligible symptomatic carotid artery stenosis have similar outcomes.

Historical note and terminology

The meaning of amaurosis fugax, or transient visual loss, has evolved throughout the years, reflecting the improved understanding of the pathophysiology. In the early 1800s, amaurosis fugax merely meant loss of sight (32). In the 1830s, the term described fleeting blindness, regardless of laterality or etiology. In the early 1900s, the term “transient monocular blindness” was often used interchangeably with amaurosis fugax. The terms used encompassed a diverse set of symptoms, but only occasionally referred to a specific etiology of visual loss. In the past decade, amaurosis fugax has been defined as transient monocular visual loss, usually of vascular origin. For the purposes of this review, the working definition of amaurosis fugax will be unilateral or bilateral transient visual loss due to retinal ischemia.

Clinical manifestations

Presentation and course

	• Amaurosis fugax is transient, painless vision loss, resembling a curtain or shade descending over the eye.
	• Fundoscopic examination may initially be normal.
	• Positive visual phenomena like scintillations may cause confusion with migraine.
	• If triggered by bright light, amaurosis fugax suggests severe carotid stenosis.
	• Ocular ischemic syndrome was described with internal carotid occlusion.

Although amaurosis fugax is classically described as a “curtain” or “shade” descending over the eye(s), patients complain more often of a blur, cloud, or fog over their vision. The episodes may be monocular or binocular, depending on the etiology. A homonymous visual field defect indicates a lesion involving the posterior visual pathways.

Rapid onset of painless altitudinal visual loss lasting 10 minutes or less suggests high-grade carotid stenosis (29). The visual manifestations range from total blindness to blurring or dimming of vision or visual field defect (101). Nearly one-third of patients with amaurosis fugax and internal carotid stenosis greater than 75% experience prolonged attacks and scintillations resembling retinal migraine (43). A bruit over the ipsilateral carotid bifurcation occurs in up to two-thirds of patients.

Binocular vision impairment suggests bilateral carotid disease (110). Alternating amaurosis fugax associated with high D-dimer may be seen in malignancy and stops after tumor resection (63).

Amaurosis triggered by bright light was seen with internal carotid artery stenosis greater than 90% (35). Internal carotid artery occlusion may cause pupillary dilatation that is poorly reactive to light, neovascularization of the iris, proliferative retinopathy, microaneurysms, scattered flame-shaped hemorrhages, prominent venous stasis, and secondary glaucoma (31; 124).

Hypoperfusion caused by central retinal artery stenosis is aggravated by bending down and diagnosed by fluorescent angiography (24). Pain, Horner syndrome, dysgeusia, and scintillations triggered by postural changes or exposure to bright light suggest carotid artery dissection (13; 07).

Non-embolic amaurosis fugax is perceived as grey, white, black, or phosphenes. It is usually patchy, occasionally associated with migraine, and tends to recover in the reverse order of appearance. A response to nifedipine suggests vasospasm (86; 87).

Bilateral optic disc swelling usually reflects elevated intracranial pressure, whereas unilateral papilledema suggests ischemia, inflammation, or infiltration. Optic disc atrophy is seen in patients with residual visual impairment.

Retinal embolism was reported by Gowers (44). Hollenhorst described cholesterol crystals in the retinal circulation. However, retinal vessels typically look normal during an episode of amaurosis fugax, even if the central retinal artery is occluded (37).

Retinal cholesterol embolus

In this photo of a retinal cholesterol embolus ("Hollenhorst plaque"), note the bright, refractile nature of the lesion, as well as the typical location at a bifurcation of vessels. Note also the lack of distal retinal ischemia...

Table 1. Retinal Emboli

Characteristic	Cholesterol	Platelet-fibrin	Calcium
Appearance Number Location Mobility Retinal ischemia Source	Elongated; pulsatile Multiple Bifurcations Can fragment and propagate Rare Ipsilateral internal carotid artery (most often)	White, creamy Often multiple Temporal arcades Mobile or fixed Frequent Internal carotid artery, arch, heart	Gray-white Usually single On or near disc Fixed Frequent Heart

Retinal embolism correlates poorly with the severity of carotid artery stenosis and should prompt further investigations (98). Venous tortuosity and midperipheral hemorrhages suggest impaired ocular perfusion (ie, ocular ischemic syndrome).

One case of recurrent amaurosis fugax associated with choreiform movements of the contralateral side was described as limb shaking transient ischemic attack that resolved after carotid endarterectomy (68).

Uhthoff phenomenon is the worsening of neurologic symptoms, including vision, in patients with multiple sclerosis after exercise, or with elevation of core body temperature. It may affect one or both eyes, lasts for seconds to minutes, and reveals preexisting optic nerve demyelination (103).

Prognosis and complications

Recurrence of amaurosis fugax is highest in the first month (06). The risk of stroke increases with severity of stenosis but is three times lower than after the first transient ischemic attack (105). Nevertheless, brain MRI detected silent acute cerebral infarctions in 23% of patients with retinal artery occlusion and amaurosis fugax (65).

Stroke, myocardial infarction, or vascular death were predicted by occurrence of more than three attacks, involvement of the peripheral visual field, constricting visual field, downward progression of visual loss, or upwards resolution of visual loss. The annual incidence of these vascular events was 4.4% (115).

The risk of stroke is highest shortly after the initial event, approximately 6.4% in the first 3 days, and increases to 26% at 14 days (111). In another study, patients with symptomatic internal carotid artery stenosis greater than 70% had a risk of stroke of 2% at day 2 and 7.5% at day 30, lower than earlier reported (106).

Permanent visual impairment occurs in approximately 1% per year (62). In young patients without stroke or systemic, cardiac, or carotid disease, even recurrent amaurosis fugax has a benign prognosis (109).

Mortality after amaurosis fugax is the same as after transient ischemic attack and lower compared to stroke (Poole and Ross 1985). The risk of vascular death in patients with amaurosis and atheromatous carotid disease is 3.5% per year and is largely due to cardiac death (48).

Clinical vignette

A 66-year-old woman presented with a 3-week history of visual spells. The spells had no clear precipitants and consisted of sudden darkening of vision in her left eye. There were no other neurologic symptoms, eye pain, or headache. The spells lasted between 30 seconds and several minutes and abated as suddenly as they began. During the last spell, she covered the left eye and noticed normal vision in the right eye. She had a history of hypertension and noninsulin-dependent diabetes mellitus. Her medical history was negative for eye problems, head pain, jaw pain, weight loss, migraine, and cardiac disease.

Her blood pressure was 136/80 mmHg with a regular heart rate of 76. The funduscopic and the rest of neurologic examination were normal.

Electrocardiogram revealed normal sinus rhythm. CT scan of the brain was normal. Carotid Doppler revealed 80% to 99% stenosis of the left internal carotid artery and normal right internal carotid artery.

After endarterectomy of the left internal carotid artery, she received aspirin and a high-dose statin and remained asymptomatic.

Biological basis

	• Visual loss in amaurosis fugax is caused by hypoperfusion of retina, choroid, or optic nerve.
	• Hypoperfusion has many causes involving the arterial diameter, perfusion pressure, coagulopathy, and embolism.
	• Causes of arterial narrowing include atherosclerosis, vasospasm, inflammation, dissection, and external compression.
	• Perfusion pressure is determined by systemic blood pressure and venous drainage.
	• Embolism has multiple causes, including cardiac arrhythmia, valvopathy, large artery atherosclerosis, abnormal thrombus formation, and thrombophilia.

Etiology and pathogenesis

Visual loss in amaurosis fugax is due to retinal, choroidal, or optic nerve hypoperfusion. Positive visual phenomena result from decreased ocular perfusion pressure during postural changes or increased retinal oxygen demand by exposure to bright light (35; 94).

Ocular ischemia is caused by carotid artery disease, cardioembolism, small artery occlusion (anterior ischemic optic neuropathy, vasculitis), vasospasm, venous disease, systemic and hypercoagulable disorders (hyperviscosity, antiphospholipid antibody syndrome), and systemic hypoperfusion. In one study, amaurosis fugax was more often associated with carotid stenosis than atrial fibrillation (05).

Internal carotid artery stenosis. Internal carotid artery stenosis may be caused by atherosclerosis or inflammation. Atherosclerosis typically occurs at the level of carotid bifurcation. A moderate size plaque may become symptomatic due to intraplaque hemorrhage or superimposed thrombosis. Amaurosis fugax was associated with male sex, hypertension, dyslipidemia, and tobacco use (69).

Carotid artery dissection. Dissection may occur in any age group and presents as neck or facial pain, Horner syndrome, and artery-to-artery embolism (12). Recurrent episodes may be triggered by an elongated styloid process (123).

Ophthalmic artery stenosis. Rarely, if the carotid artery is normal, recurrent amaurosis fugax in the same eye is most likely caused by ophthalmic artery stenosis (117; 15; 75).

Nonvalvular atrial fibrillation. Nonvalvular atrial fibrillation, the most common cardioembolic etiology of amaurosis fugax, may be underreported. Out of 400 patients with transient or permanent monocular vision loss, of which only 53% underwent prolonged cardiac monitoring and 9% had atrial fibrillation (125). Embolism from calcified aortic stenosis or cardiac valve disease is rare (112).

Vasospasm. Vasospasm of the retinal vessels responds to calcium channel blockers (118).

Anterior ischemic optic neuropathy. Caused by short posterior ciliary artery ischemia, anterior ischemic optic neuropathy is not typically associated with carotid stenosis. Anterior ischemic optic neuropathy presents as an acute, painless unilateral visual loss with a swollen optic disc (34).

Internal jugular vein stenosis. This condition may be seen on contrast-enhanced MRI and MRA in patients with normal carotid arteries (22). Moderate to severe internal jugular stenosis may alter the ocular hemodynamics and cause flow reversal dilatation of the retinal venules. Multiple etiologies underlie the venous insufficiency, like external compression from bone muscle structures, embryological defect, and infectious or inflammatory disorders (26) and increased resistance in the retrobulbar arteries (19).

Severe hypotension. Ischemic anterior or posterior optic neuropathy may be associated with cerebral watershed ischemia (53). Hypoperfusion of the occipital lobes may cause bilateral visual loss. The symptoms are triggered by posture, especially in the presence of carotid stenosis.

Thrombophilia. Thrombophilia may cause amaurosis fugax (40). Personal or family history of thromboembolism, miscarriage, skin rash, false positive test for syphilis, and coagulopathy should raise the suspicion of antiphospholipid antibody syndrome or congenital coagulopathy. Testosterone is prothrombotic (41).

Orbit mass lesions. Gaze-evoked amaurosis caused by orbit tumors may be associated with proptosis, globe indentation, and papilledema (99).

Migraine. Transient visual loss during migraine is caused by cortical spreading depression. Retinal migraine is very rare (50). Some patients developed permanent visual loss during migraine; unfortunately, the mechanism in most cases was not specified (45).

Other causes. Other causes of amaurosis fugax include giant cell arteritis (30), IgG4 disease (72), Takayasu arteritis (33; 09), Tolosa-Hunt syndrome (58), moyamoya disease (81), neurosarcoidosis (59), neurocysticercosis (102), visual seizures (97), cervical rib causing thoracic outlet syndrome (55), inferior alveolar nerve block during dental procedures (114), glaucoma, blowing of the nose, intraocular hemorrhages, and malaria (85). Preeclampsia is associated with a multitude of visual disturbances, including amaurosis fugax (92). Recurrent hypnic amaurosis fugax may occur on awakening, with full recovery of vision (108).

Prevention

	• Amaurosis fugax shares cerebrovascular risk factors with carotid artery disease.
	• Controlling the cerebrovascular risk factors is key to preventing stroke.
	• Most patients benefit from antiplatelet and high-dose statins.
	• Anticoagulation is indicated in patients with atrial fibrillation, flutter, or intracardiac thrombus.
	• Endarterectomy is beneficial for patients with three or more risk factors: age over 75 years, male sex, history of transient ischemic attack or stroke, and life expectancy of a minimum of 5 years.
	• Carotid artery angioplasty and stenting have similar outcomes as carotid endarterectomy.
	• There is no standard treatment for intracranial carotid artery stenosis.

Amaurosis fugax shares the risk factors with internal carotid artery disease and stroke: old age, history of diabetes mellitus, myocardial infarction, hypertension, and smoking (11).

Lifestyle modification by promoting low-salt and Mediterranean diets, physical activity, and medication compliance is important for preventing stroke (61).

NASCET demonstrated the superiority of carotid endarterectomy to medical therapy alone in symptomatic patients with internal carotid stenosis greater than 70% (82). However, the perioperative stroke and death rates are substantially lower in patients presenting with amaurosis fugax compared to those presenting with hemispheric transient ischemic attack or minor stroke (93).

Carotid endarterectomy helped if three or more of the following risk factors were present: male sex older than 75 years, history of transient ischemic attack or stroke, history of intermittent claudication, ipsilateral stenosis of 80% to 94%, or absent collaterals on angiography (10). Carotid endarterectomy should only be offered to high-risk patients with a minimum life expectancy of 5 years. The procedure should only be performed in a center with acceptable morbidity and mortality (21).

Initially reserved for high-risk patients, carotid artery stenting has been proven to have a similar outcome as carotid endarterectomy. Although the perioperative risk was low, endarterectomy was associated with more cases of myocardial infarction, whereas carotid artery stenting was associated with more strokes (71).

The patients enrolled in NASCET were not provided with the current intensive medical therapy. Several interventional trials failed to show a significant advantage over medical therapy due to the lower-than-expected rate of stroke in the medical arm (23; 89). The declining stroke recurrence over the past decades is attributed to better hypertension control and antithrombotic medications and has important implications in trial design (51).

The optimal timing of carotid endarterectomy is between 48 hours and 7 days if early revascularization is not contraindicated (90). Progressive or fluctuating symptoms were associated with worse outcomes after urgent carotid endarterectomy (91; 08).

If internal carotid artery stenosis is intracranial, aspirin and warfarin are equally effective in preventing stroke (79). Intensive medical therapy (with an antiplatelet, high-dose statin, blood pressure, and diabetes control coupled with smoking) avoidance prevents more strokes than angioplasty and stenting in patients with large intracranial arterial stenosis (23; 27).

Patients with atherosclerotic internal carotid artery occlusion do not benefit from a surgical bypass between the external and internal carotid arteries despite excellent cerebral reperfusion (89; 46). An alternative intervention for symptomatic internal carotid artery occlusion is stenting of the external carotid artery if stenotic (122). However, further studies are needed to validate this approach.

Cardiac embolism caused by atrial fibrillation, flutter, metallic valve, or intracardiac thrombus is prevented by either warfarin or direct oral anticoagulation (61).

Internal carotid artery dissection can be treated with either antiplatelet or anticoagulation (76; 57).

Initially, 50 to 325 mg/day of aspirin is used for stroke prevention after amaurosis fugax. Clopidogrel, is slightly more effective in preventing recurrent stroke than aspirin (17). Low-dose aspirin combined with extended-release dipyridamole may be more effective than aspirin alone in secondary stroke prevention (20). A Cochrane review showed that aspirin plus extended-release dipyridamole prevents more recurrent events than aspirin alone, only in patients with a history of cerebral ischemia (28).

In patients with symptomatic carotid stenosis, after a transient ischemic attack, early statin therapy reduces the 7-day risk of stroke from 13.2% to 3.8% (77). High-dose statin therapy reduces the 5-year absolute risk for cardiovascular events by 3.5% (03).

The ocular ischemic syndrome caused by the internal carotid artery occlusion may benefit from lowering the intraocular pressure to improve ocular perfusion. Panretinal photocoagulation is indicated if a fluorescein angiogram reveals retinal ischemia. Carotid artery revascularization improves ocular perfusion and visual acuity (56).

In patients with visual symptoms caused by migraine, it is unclear if the calcium channel blockers, beta-blockers, or anticonvulsants also prevent the visual aura (118).

Differential diagnosis

Amaurosis fugax may reflect a wide variety of pathologic processes. Because most patients are evaluated after the attack, the neurologic and ophthalmologic examination may be normal; therefore, obtaining a careful history is imperative. It is important to establish whether the visual loss was monocular or binocular. Binocular visual loss suggests vertebrobasilar ischemia, migraine, or seizures. Seizures may cause altered consciousness or eye deviation. They are typically maximal at onset and in contrast to migraine, which evolves gradually.

Ipsilateral carotid artery stenosis. Ipsilateral carotid artery stenosis is suggested by monocular vision loss. Vision loss may be complete in 48% of patients; it may be sectorial or respect the horizontal meridian and suggests retinal artery branch occlusion (85).

Idiopathic intracranial hypertension (pseudotumor cerebri). Idiopathic intracranial hypertension presents as visual obscurations lasting seconds during bending forward of the head.

Thromboembolism. Thromboembolism typically lasts 2 to 10 minutes and may be associated with hemispheric symptoms.

Migraine aura. Migraine aura manifests as homonymous hemianopia and lasts 20 to 30 minutes. It is occasionally associated with scintillating scotomas and brainstem dysfunction, like dysarthria, dysphagia, vertigo, and diplopia. Migraine aura is isolated in less than 1% of cases (16). There should be at least two attacks with symptoms that evolve over at least 5 minutes, last up to 1 hour, and are fully reversible. Migraine with aura, typical aura with non-migraine headache, and typical aura without headache may cause homonymous and unilateral visual symptoms, such as flickering lights or blurry vision. However, these symptoms are not always due to migraine (50).

Retinal migraine. During retinal migraine, the monocular visual loss is followed by migraine without aura. In the absence of a headache, other etiologies should be ruled out first (49). Retinal migraine does not cause permanent visual loss (50). Arterial spasm and ocular hypoperfusion may be observed during fundus examination or with retinal angiography (52).

Giant cell arteritis. Giant cell arteritis causes transient visual loss and diplopia, particularly in elderly patients with temporal artery induration, scalp tenderness, jaw claudication, polymyalgia rheumatica, papilledema, and elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP). The most feared complication is blindness due to inflammatory occlusion of the ophthalmic and ciliary artery branches. Temporal artery biopsy provides the definitive diagnosis.

Takayasu arteritis. Takayasu arteritis involves the large arteries and leads to decreased peripheral pulses. Retinopathy may be suspected if there is a delayed arm-to-retina circulation time (25).

Rheumatoid arthritis. Rheumatoid arthritis may affect the small and medium size blood vessels and presents as amaurosis fugax in patients with multiple proximal joint aches (01).

Table 2. Clinical Features and Common Causes of Transient Visual Loss

Etiology	Duration	Pattern of visual loss	Associated findings	Mechanism
Migraine with aura	10 to 20 minutes	Binocular, hemianopic, scintillations, typical buildup of symptoms	Usually followed by headache with migrainous quality	Spreading cortical depression
Retinal migraine	10 to 20 minutes	Monocular, retinal (quadrantic, altitudinal) choroidal (concentric)	Headache, positive family history	Vasospasm
Vertebrobasilar insufficiency	Seconds	Binocular, concentric or blurring	Posture-related vertigo, diplopia	Orthostatic hypotension, arrhythmia, autonomic insufficiency, V-B stenosis
Retinal emboli	3 to 5 minutes	Monocular, quadrantic, altitudinal	Hollenhorst plaque, ipsilateral carotid bruit	Emboli from ipsilateral internal carotid artery, aortic arch heart, paradoxical
Papilledema	Seconds	Monocular with each occurrence; gray-out, blur	Headache pulsatile tinnitus, diplopia	Venous stasis, poor arterial perfusion
Seizure	(Ictal) 3 to 5 minutes; (postictal) 10 to 20 minutes	Binocular, may have positive phenomena, no build-up	Altered consciousness, eye deviation	Idiopathic (children); occipital lesion (adults)

Dry eyes. Dry eyes may cause mild transient visual blurring relieved after a few seconds by blinking, rubbing the eyes, or using lubricating eye drops.

Other ophthalmologic conditions. Angle-closure glaucoma, impending central retinal vein occlusion, and congenital optic disc anomalies may also cause amaurosis but are readily detected on ophthalmologic examination. Increased intraocular pressure after vitreoretinal surgery may cause ipsilateral amaurosis fugax (104). Microhyphema, which can only be visualized by gonioscopy, may cause a “snow globe” effect in the anterior chamber and cause vision loss triggered by bending over (66).

Diagnostic workup

	• Carotid ultrasound is noninvasive but less accurate than other imaging modalities.
	• Computer tomographic angiography requires intravenous contrast and is more accurate than ultrasound.
	• Magnetic resonance angiography does not require contrast but may be contraindicated in some patients with inserted metallic devices.
	• Conventional 4-vessel angiography is the gold standard of vascular imaging. Its limited availability and invasive nature limit its utility.
	• Fluorescein angiography visualizes retinal vasculature and perfusion.
	• FDG-PET scan alone or in combination with CTA and MRA may detect vulnerable nonobstructive atherosclerotic plaques.

The risk of stroke depends on the degree of arterial stenosis and the characteristics of the vulnerable atherosclerotic plaque. Embolic stroke of undetermined source (ESUS) may also occur in patients with nonstenotic (with < 50% stenosis) plaques. In a study of 138 patients with ESUS, 39.1% of patients had nonstenotic carotid plaques and 8.7% had bilateral carotid plaques; 60.6% of these plaques were ipsilateral to the side of the stroke, suggesting a causal relationship (83).

Carotid ultrasonography. This noninvasive method estimates the degree of arterial stenosis from blood flow velocity and characterizes the vessel wall configuration and plaque morphology. Intravenous contrast helps differentiate thrombosis from dissection (107; 47).

Carotid ultrasonography can reveal plaque morphology, such as echodensity (95; 73), juxtaluminal hypoechoic area (54), and enhancement (84). In asymptomatic carotid stenosis of any severity, a combination of plaque features (matrix, intraplaque hemorrhage, wall thickness, plaque burden), age, body mass index, and lipid profile better predicts major neurologic events compared to the severity of arterial stenosis alone (64).

Color Doppler. The color Doppler of the orbit can demonstrate ophthalmic artery stenosis, retrolaminar emboli, and reversal of direction of ophthalmic artery flow in the ocular ischemic syndrome (74).

Computed tomography angiography. Computed tomography angiography can accurately measure the degree of carotid stenosis and evaluate plaque morphology (119). Three-dimensional reconstruction (3D-CTA) may help in selecting patients before carotid revascularization (121).

Magnetic resonance angiography (MRA) of the neck. A noninvasive method of measuring the arterial diameter, MRA tends to overestimate the degree of stenosis. This can be corrected by using contrast. Either a high-quality noninvasive test alone or in combination with angiography may be adequate for patient evaluation (42). Jugular vein stenosis may be seen in the absence of internal carotid artery stenosis (22).

Detection of the vulnerable, unstable plaque and the risk stratification may be enhanced by using dual-targeted microparticles of iron oxide (DT-MPIO) (during MRI imaging) (70; 18).

Fluorescein retinal angiography. This technique is useful for evaluating the retinal and choroidal circulation and may demonstrate occlusive disease, retinal edema, and hypoperfusion.

Digital subtraction cerebral angiogram. Digital subtraction cerebral angiogram may visualize the ophthalmic artery not seen on CT or MR angiogram but not the distal short posterior ciliary and central retinal arteries. One severe complication of the cerebral angiogram is diffuse vasospasm of the internal carotid and ophthalmic arteries. This may be confirmed by increased blood flow velocity on carotid Doppler (100).

Cardiac evaluation. Cardiac evaluation includes electrocardiography, transthoracic echocardiography, or transesophageal echocardiography. Transesophageal echocardiography is more sensitive than transthoracic echocardiography at finding embolic sources (120). Prolonged cardiac monitoring with portable or insertable monitors may improve detection of atrial fibrillation (67; 39; 60; 96).

Positron emission scan (PET) scan. [(18)F]-fluorodeoxyglucose-PET (FDG-PET) imaging has emerged as a valuable tool targeting atherosclerotic plaque glycolysis, a marker for plaque inflammation and hypoxia (14). Evaluation of nonstenotic atherosclerotic plaques with FDG-PET-CT angiography found increased FDG uptake and more frequent as well as more extensive hypodense lesions on CTA ipsilateral to the stroke, suggesting a role in stroke etiology (78). In addition, increased [(18)F]-fluorocholine uptake may signal a symptomatic vulnerable plaque (116).

Inflammatory and hypercoagulable markers. Inflammatory systemic and hypercoagulable disorders, particularly those predisposing to arterial thrombosis, may affect selected patients. These include young patients without vascular risk factors, or a family history of unexplained thrombosis. Laboratory testing includes anticardiolipin antibodies, lupus anticoagulant, erythrocyte sedimentation rate, ESR, CRP, sickle cell screen, and toxicology. Temporal artery biopsy for ultrasound may detect giant cell arteritis in elderly patients with headache, jaw claudication, scalp tenderness, elevated ESR or CRP, or thrombocytosis.

Uric acid. Xanthine oxidase, an enzyme involved in uric acid synthesis, is overexpressed in the macrophages collected from the symptomatic plaques (36). Serum uric acid concentration is increased and may be a useful marker in patients with symptomatic carotid stenosis (80).

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Contributors

All contributors' financial relationships have been reviewed and mitigated to ensure that this and every other article is free from commercial bias.

Author

Adrian Marchidann MD

Dr. Marchidann of Kings County Hospital has no relevant financial relationships to disclose.
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Editor

Steven R Levine MD

Dr. Levine of the SUNY Health Science Center at Brooklyn has no relevant financial relationships to disclose.
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Former Authors

Edward Feldmann MD
Gregory P Van Stavern MD
Christopher C Glisson DO

Patient Profile

Age range of presentation: 13 to 65+ years
Sex preponderance: Male>female except for age group 35 and 44 years (Andersen et al 1988)
Heredity: Heredity may be a factor
Population groups selectively affected: none selectively affected
Occupation groups selectively affected: none selectively affected

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Amaurosis fugax

Associated Disorders

Anemia
Angina
Angle closure glaucoma
Anterior ischemic optic neuropathy
Antiphospholipid antibody syndrome
- Atherosclerosis
- Atrial fibrillation
- Atrial myxoma
- Bilateral transient visual loss
- Brain tumor
- Cardiomyopathy
- Diabetes mellitus
- Endocarditis
- Hypertension
- Hyphema
- Internal carotid artery dissection
- Internal carotid artery occlusive disease
- Mitral valve prolapse
- Myocardial infarction
- Ophthalmologic diseases
- Patent foramen ovale
- Polycythemia
- Polymyalgia rheumatica
- Retinal migraine
- Rheumatic heart disease
- Temporal arteritis
- Transient monocular visual loss
- Unilateral transient visual loss
- Vasculitis

Differential Diagnosis

ipsilateral internal carotid artery atherosclerosis
ipsilateral internal carotid artery dissection
cardiac embolism
vertebrobasilar ischemia
migraine
- seizure
- papilledema
- Primary postural hypotension
- Secondary postural hypotension
- Malignant hypertension
- Reduced ocular perfusion
- Hyperviscosity
- Vasospasm
- Vasculitis
- Arteriovenous fistula
- Uhthoff phenomenon
- ocular diseases (papilledema, drusen, intraocular hemorrhages)
- recurrent angle closure glaucoma
- impending central retinal vein occlusion
- congenital optic disc anomalies
- Takayasu arteritis
- rheumatoid arthritis

Also Relevant

Carotid bruit
Carotid TIAs
Temporal arteritis
Transient visual loss
Vertebrobasilar TIAs

Clinical Categories

Stroke & Vascular Disorders

Web References

Clinical Trials

NIH: Transient Ischemic Attack

	• Amaurosis fugax occurs in all age groups.
	• Elderly patients have predominantly ischemic causes of amaurosis fugax.
	• Young patients have migraine or unknown causes of amaurosis.

	• Amaurosis fugax is a medical emergency.
	• There is no treatment for amaurosis fugax.
	• Urgent evaluation is important for prompt initiation of stroke prevention.

Amaurosis fugax

Introduction

Overview

Key points

Historical note and terminology

Clinical manifestations

Presentation and course

Table 1. Retinal Emboli

Prognosis and complications

Clinical vignette

Biological basis

Etiology and pathogenesis

Epidemiology

Prevention

Differential diagnosis

Table 2. Clinical Features and Common Causes of Transient Visual Loss

Diagnostic workup

Management

Outcomes

Special considerations

Pregnancy

Anesthesia

Media

References

Contributors

Author

Editor

Former Authors

Patient Profile

ICD & OMIM codes

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Questions or Comment?

Also in This Category

Ischemic stroke

Cerebral embolism

Hormonal contraception and stroke

Antiphospholipid antibody syndrome

Sleep, stroke, and vascular dementia

Vein of Galen malformations

Patent foramen ovale

Neuroimaging in acute stroke

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