From the Guidelines
Amaurosis fugax diagnosis should be approached with a comprehensive evaluation including a detailed medical history, physical examination, and targeted diagnostic tests, prioritizing the identification of carotid stenosis as a common cause, as recommended by the 2011 ASA/ACCF/AHA/AANN/AANS/ACR/ASNR/CNS/SAIP/SCAI/SIR/SNIS/SVM/SVS guideline 1. The diagnosis begins with identifying the characteristic symptom of temporary monocular vision loss, often described as a "curtain" coming down over one eye. Initial assessment should include a complete eye examination, blood pressure measurement, and auscultation of the carotid arteries for bruits. Key diagnostic considerations include:
- Carotid artery stenosis or occlusion
- Atherosclerosis
- Dissection
- Arteritis
- Radiation-induced arteriopathy
- Arterial embolism
- Cardiogenic embolism
- Atheroembolism
- Hypotension
- Intracranial hypertension
- Glaucoma
- Migraine
- Vasospastic or occlusive disease of the ophthalmic artery, as outlined in the guideline 1. Laboratory tests should include a complete blood count, erythrocyte sedimentation rate, C-reactive protein, lipid profile, and blood glucose. Imaging studies are crucial and should include carotid duplex ultrasonography to assess for carotid stenosis, which is a common cause of amaurosis fugax, as noted in the guideline 1. Additional imaging may include magnetic resonance imaging (MRI) of the brain, magnetic resonance angiography (MRA) of the head and neck, or computed tomography angiography (CTA). Cardiac evaluation with an electrocardiogram and echocardiogram is important to rule out cardiac sources of emboli. In some cases, fluorescein angiography may be performed to evaluate retinal circulation. Prompt diagnosis is essential as amaurosis fugax can be a warning sign of an impending stroke, and identifying the underlying cause allows for appropriate treatment to prevent more serious vascular events, with the 3-year risk of stroke with medical treatment alone in patients with transient monocular blindness related to the number of stroke risk factors, as reported in the guideline 1.
From the Research
Diagnosis of Amaurosis Fugax
- Amaurosis fugax is a term used to denote momentary visual loss from transient retinal ischemia, and it is considered a type of transient ischemic attack (TIA) 2.
- The diagnosis of amaurosis fugax involves a comprehensive evaluation, including a detailed history and examination, followed by specific diagnostic studies such as imaging of the brain and extracranial and intracranial blood vessels 2.
- Cardiac investigations and serum studies to evaluate for etiological risk factors are also recommended 2.
- An algorithm for evaluation of amaurosis fugax includes ophthalmic examination, laboratory studies, and noninvasive carotid artery studies 3.
Diagnostic Criteria
- Transient ischemic attack (TIA) is defined as a transient episode of neurological dysfunction resulting from focal brain, spinal cord, or retinal ischemia, without associated infarction 2.
- Amaurosis fugax is characterized by transient visual loss, which is presumed to be due to ischemia 4.
- Clinical features such as carotid bruit, transient cerebral ischemic attacks, hypertension, and claudication are associated with a high prevalence of angiographic abnormality in the internal carotid artery 5.
Diagnostic Tests
- Imaging of the brain and extracranial and intracranial blood vessels forms the cornerstone of diagnostic workup of TIA, including amaurosis fugax 2.
- Carotid ultrasound is a useful diagnostic test for evaluating patients with amaurosis fugax 6.
- Angiography may be indicated in patients with certain clinical features, such as carotid bruit, transient cerebral ischemic attacks, hypertension, and claudication 5.