From the Guidelines
Amaurosis fugax is a medical emergency that requires immediate attention, as it can be a warning sign of an impending stroke, and patients should go to an emergency room immediately if they experience it. This condition is a temporary loss of vision in one eye, typically lasting a few minutes, caused by reduced blood flow to the retina, and it presents as a "curtain" or "shade" coming down over the vision, often described as a transient monocular blindness 1. The most common cause is atherosclerosis of the ipsilateral internal carotid artery, but other causes have been associated with this syndrome as well, including carotid artery stenosis or occlusion, dissection, arteritis, radiation-induced arteriopathy, arterial embolism, cardiogenic embolism, atheroembolism, hypotension, intracranial hypertension, glaucoma, migraine, and vasospastic or occlusive disease of the ophthalmic artery 1.
The risk of stroke was lower among patients with transient monocular blindness than among those with hemispheric TIA in the NASCET cohort, but the 3-year risk of stroke with medical treatment alone in patients with transient monocular blindness was related to the number of stroke risk factors, and was specifically 1.8% in those with 0 or 1 risk factor, 12.3% in those with 2 risk factors, and 24.2% in those with 3 or 4 risk factors 1. Treatment typically includes antiplatelet therapy, such as aspirin (81-325 mg daily), along with management of underlying risk factors like hypertension, diabetes, and high cholesterol. In some cases, carotid endarterectomy may be recommended if significant carotid artery stenosis is found. The condition occurs when small emboli temporarily block the retinal artery, reducing oxygen supply to the retina, and these emboli often originate from atherosclerotic plaques in the carotid arteries or from the heart 1.
Some key points to consider in the management of amaurosis fugax include:
- Prompt evaluation and treatment are essential to prevent more serious vascular events like stroke
- Patients with acute retinal arterial ischemia should be referred to specialized stroke centers without attempting to perform any further testing themselves
- The development of local networks prompting collaboration among optometrists, ophthalmologists, and stroke neurologists should facilitate such evaluations
- Acute retinal arterial ischemic events are classic causes of acute painless monocular vision loss, and are associated with high cerebrovascular and cardiovascular morbidity and mortality 1.
In summary, amaurosis fugax is a serious condition that requires immediate medical attention, and treatment should focus on preventing further vascular events, managing underlying risk factors, and potentially performing carotid endarterectomy if significant carotid artery stenosis is found.
From the Research
Definition and Classification of Amaurosis Fugax
- Amaurosis fugax is an all-inclusive term for all forms of transient visual loss, which can be divided into four identifiable symptom complexes: embolic, hypoperfusion, angiospasm, and unknown 2.
- It is a subjective phenomenon caused by a transient and temporary ceasing of the retinal blood flow, and can be classified into four types according to the mechanisms involved: embolic, hypoperfusion, angiospasm, and idiopathic 3.
Relationship with Carotid Artery Stenosis
- Amaurosis fugax has frequently been related to carotid artery disease, and a high correlation (0.87) was found between ulcerated plaque and amaurosis fugax 4.
- Patients with significant carotid stenosis (greater than 70%) were found to have a high prevalence of hypertension, smoking, and previous CVA/TIAs, and carotid duplex scan is recommended if this symptom is present 4.
Diagnosis and Treatment
- The diagnosis of amaurosis fugax involves ophthalmic examination, laboratory studies, and noninvasive carotid artery studies, and an algorithm for evaluation is available 5.
- Treatment of atherosclerosis, carotid artery disease, and other causes of amaurosis fugax are also discussed, and urgent therapy is necessary in attack of illnesses 6, 5.
- Sequencing in therapy of amaurosis fugax is emphasized, and the cause of the disease may be defined within 24 hours 6.