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Amaurosis Fugax
Amaurosis Fugax: Understanding Temporary Vision Loss and Stroke Risk
Did you experience a sudden loss of vision in one eye? Could be amaurosis fugax (AFx) or a retinal transient ischemic attack (rTIA), an important warning sign for your vascular health. Learn what they are, why they occur, and the urgency of diagnosing and treating them. prevent a stroke.
What Are Amaurosis Fugax and rTIA?
The amaurosis fugax (AFx) is a transient monocular vision loss causada por la temporary retinal ischemia. This means that blood flow to the retina is suddenly and reversibly reduced, often due to embolic events or changes in hemodynamics.
The rTIA is a more specific term for this temporary loss of vision resulting from transient retinal ischemia. It is considered a type of transient ischemic attack (TIA) which affects ocular circulation. The retina is very sensitive to a lack of oxygen due to its high metabolic demand, which leads to this temporary vision loss.
Main Causes of Retinal Ischemia
The most common cause of transient retinal ischemia is thromboembolic events. Small fragments (cholesterol, fibrin-platelet or calcium emboli) are usually released from the atherosclerotic plaques in the ipsilateral carotid artery, the heart or the aortic arch, and travel until they temporarily block the retinal arteries.
Other less common causes include:
- Vasospasm of the retinal arteries
- Arterial dissection (such as carotid artery dissection)
- Vasculitis (especially the giant cell arteritis)
- Hypercoagulable states
- In rare cases, transient increases in intraocular pressure or external ocular compression.
Characteristic Symptoms and How to Diagnose
The most distinctive symptom of AFx/rTIA is the transient monocular vision loss (TMVL), often described as a "curtain" or "shadow" that falls or rises across the visual field of the affected eye. Vision loss is sudden and lasts from seconds to several minutes, almost always resolving in less than an hour. If it lasts longer, it could indicate a retinal artery occlusion.
The diagnosis of AFx/rTIA is based on:
- A detailed medical history: It is crucial to investigate the nature of the visual loss, the associated symptoms and the risk factors for vascular disease (such as hypertension, diabetes or smoking).
- A complete physical examination: Includes a thorough neurological evaluation to rule out persistent deficits. In the fundus examination, the physician will look for Hollenhorst plates, which are retinal emboli.
It is essential to differentiate rTIA from other causes of transient monocular vision loss, such as ocular migraine or visual obscurations associated with papilledema.
The Importance of a Rapid Assessment: Stroke Risk
The rTIA is considered a emergencia médica due to the significantly increased risk of stroke This risk can be 3% to 10% in the first two days and 9% to 17% in the first 90 days after the event, a risk similar to that of TIAs affecting the central nervous system (CNS).
Risk scales are used such as ABCD2 (and its modifications ABCD3 and ABCD-I) to assess stroke risk after a TIA.
Management and Treatment: Aggressive Stroke Prevention
The management of rTIA/AFx is similar to that of cerebral TIAs, focusing on the stroke prevention.
It is recommended one urgent diagnostic evaluation to identify underlying causes that can be addressed. This includes:
- Cerebral and vascular imaging studies: Such as carotid Doppler ultrasound and CT or MRI angiography.
- Cardiac evaluation: Electrocardiogram (ECG) and echocardiogram.
- Laboratory tests.
The medical treatment commonly includes:
- Antiplatelet therapy: Aspirin or clopidogrel to reduce the risk of further ischemic events.
- Anticoagulation: Indicated in cases of cardioembolic sources, such as atrial fibrillation.
The modification of risk factors It is vital: to control the hypertension, the diabetes, the hyperlipidemia and quit smoking. Lifestyle changes, such as a healthy diet and regular exercise, are also recommended.
In patients with significant carotid stenosis, it can be considered the carotid endarterectomy or the angioplasty with stenting to reduce the risk of stroke. It is recommended that all patients with TIA/AFx receive antiplatelet therapy prior to further evaluation. In high-risk patients, short-term dual antiplatelet therapy (aspirin and clopidogrel).
The Critical Role of the Ophthalmologist in Diagnosis
The oftalmólogos son fundamentales en el reconocimiento temprano y el manejo adecuado del rTIA. Deben tener un alto índice de sospecha ante pacientes que presenten transient monocular vision loss, especialmente si tienen factores de riesgo vascular conocidos.
It is essential to obtain a detailed medical history of the visual symptoms and perform a complete ophthalmological examination, buscando signos como las Hollenhorst plates. Given the urgency of the stroke risk, the immediate referral to a stroke center or neurologist for a comprehensive systemic assessment is essential.
Amaurosis fugax and transient retinal ischemic attack are crucial manifestations of underlying vascular disease and significant predictors of future serious ischemic events. Their timely recognition and management are essential to reduce stroke risk and prevent permanent vision loss. Ophthalmologists play a vital role in the initial identification of these patients and facilitating rapid evaluation and treatment. Current guidelines emphasize the need to treat all TIAs, including AFx, as medical emergencies, with a focus on identifying the underlying etiology and implementing aggressive secondary prevention strategies.
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