Amaurosis Fugax · What Is It, Causes, and More

Typically, amaurosis fugax is the result of narrowing or occlusion of the internal carotid artery or the central retinal artery, leading to decreased blood supply to the retina, optic nerve, or other visual pathways. One of the most common causes of amaurosis fugax is carotid artery disease, where fatty deposits called plaques narrow the blood vessels that deliver blood to the brain. Sometimes, parts of the plaque can detach from the inner lining of the artery and clog smaller blood vessels, such as the central retinal artery.   

Amaurosis fugax can also occur as a symptom of other underlying conditions. For example, transient monocular visual loss can be caused by inflammation of the optic nerve, called optic neuritis; demyelinating disorders, like multiple sclerosis; or severe head injuries. Individuals older than 60 years of age that have had multiple episodes of transient monocular blindness could also be investigated for giant cell arteritis, which is characterized by inflammation of the large vessels of the scalp, neck, and arms. Transient vision loss may also be a sign of visual aura in individuals with migraine headaches. 

Several risk factors have been associated with amaurosis fugax. Diabetes, and tobacco and cocaine use can have long-term complications affecting the small blood vessels supplying the retina. Individuals reaching an advanced age also may be more likely to experience amaurosis fugax due to higher rates of high blood pressure and hyperlipidemia (i.e., high levels of lipids in the blood), which increases the risk of carotid artery disease.  

Diagnosis of amaurosis fugax begins by obtaining a medical history and assessment of any vascular risk factors present. Individuals are typically investigated for hypertension, diabetes, hyperlipidemia, and cardiac disease, and may be asked about other risk factors like tobacco use. A detailed physical assessment, including a complete eye exam with pupil dilation may be performed to assess the optic nerve and optic disc. Additionally, auscultation of the carotid arteries and the heart may be performed. Further blood tests, including inflammatory blood markers (e.g., ESR, CRP) may also be obtained to rule out giant cell arteritis.   

If carotid artery disease is suspected, a Doppler ultrasound can be used to identify plaque build-up in the internal carotid arteries. Neuroimaging tests, such as magnetic resonance and computed tomography (CT) angiography, may also be perfomed to evaluate blood flow to the brain’s arteries and detect any occlusions.