Amaurosis Fugax: The Curtain-Over-Your-Eye Warning Sign That Can Mean a Stroke Is Coming
Amaurosis Fugax at a Glance
If a curtain or shadow slid across the sight in one eye and then cleared, do not wait for a clinic appointment. Go to the nearest emergency room, or call 911 if any of these are true:
- Your sight is still lost, or it is dim now.
- Your face droops, or one arm is weak.
- Your speech is slurred, or words are hard to find.
- You are dizzy, or you cannot walk straight.
- You have a bad new headache, or pain in your scalp or jaw.
A retinal warning stroke needs the same urgency as a brain one. You should go straight to the nearest emergency room tied to a stroke center, so the full workup is done within 24 hours. After a warning stroke of any kind, about 10 to 15 of every 100 people have a stroke within about 3 months, and more than half of those come in the first 48 to 72 hours1. That is the hard part. Here is the other half. This warning is treatable, and getting checked today is what lowers the risk that follows.
The name means 'fleeting blindness,' and it describes a symptom rather than a disease. It is a temporary, painless loss of vision in one or both eyes caused by disrupted blood flow to the retina, the loss usually lasts seconds to minutes, and people describe it as a curtain falling from the top of the eye downward or being drawn across from one side2. Episodes most often last between 2 and 30 minutes3. The vision returning is not the end of the story. It is the reason you have time to act.
Expect a stroke workup rather than an eye appointment. At the emergency department this means cardiac monitoring, blood tests, an EKG, imaging of the brain and blood vessels, and a stroke neurologist consultation, with the aim of finishing it inside 24 hours1. An eye doctor may also examine your retina. Most people are not admitted for long. The point of the visit is to find the source of the blockage and start treatment before a larger event happens.
What This Symptom Actually Means
A small clot or fragment of plaque travels into a retinal artery, blocks it briefly, then breaks up or moves on. Your sight returns because the blockage cleared, not because the problem did. One-eyed episodes most often come from carotid artery disease on the same side, with secondary thromboemboli (thromboemboli: clot fragments carried in the bloodstream)4. The same artery feeds part of your brain. That is why an eye symptom triggers a stroke workup, and why 'it went away' is not a reason to relax.
The retina is supplied by a branch of the internal carotid artery, so a retinal event is a direct report on that vessel. The usual source is an embolus from an atherosclerotic plaque at the carotid bifurcation, and the eye exam may show a carotid bruit on listening or a visible plaque fragment in a retinal vessel3. Up to 25 to 30 of every 100 brain MRIs done after a retinal warning event show acute changes in the brain1. Those changes are often silent, which is exactly why imaging is done rather than assumed.
The honest framing is urgent, not hopeless. Studies estimate that people who have amaurosis fugax and are left untreated carry roughly a 10 to 15 in 100 risk of stroke within the first year3. Read it the other way round as well: that figure describes people who were never treated, and even in that group most do not have a stroke in the year that follows. The whole purpose of the emergency visit is to move you out of the untreated group. Worry is a reasonable response today. It is not a reason to delay the trip.
What Causes a Curtain Over One Eye
This is the classic cause and the one your team looks for first. Fatty plaque builds up where the carotid artery divides in the neck, and small pieces break away and lodge in the retinal circulation. Atherosclerosis in the internal carotid artery is one of the most common causes, and the risk factors include diabetes, heart disease, smoking, high blood pressure, high cholesterol and older age3. Every one of those risk factors is something a treatment plan can act on, which is the encouraging part of an otherwise unwelcome list.
Sometimes the clot starts in the heart rather than the neck. Atrial fibrillation, as well as valvular heart disease, can lead to embolism3. Atrial fibrillation is an irregular heart rhythm that can let blood pool and clot. It often causes no symptoms at all, which is why an EKG and sometimes a longer heart monitor are part of the workup even when your heart feels perfectly normal to you. Finding it changes which medicines you are offered.
Not every case is a clot from a plaque. Giant cell arteritis, an inflammation of medium and large arteries, should be suspected in anyone older than 60 with repeated episodes3. Causes of brief vision loss in one eye fall into three groups: vascular ones such as carotid disease, a clot thrown from the heart, giant cell arteritis or spasm of a blood vessel; neurologic ones such as retinal migraine; and ophthalmic ones, meaning a problem in the eye itself4. Tell your team about any new headache, scalp tenderness or ache in the jaw while chewing, because those symptoms change what gets tested.
What the Episode Looks and Feels Like
It is painless, one-sided, and over quickly, which is precisely what makes it easy to dismiss. Vision loss is usually unilateral, painless and transient, described as a curtain coming down or a generalized darkening or shadow3. Some people notice only when they cover the good eye later. Others see a grey haze rather than a black curtain. Positive visual symptoms such as flickering do not rule out an ischemic cause4, so an unusual description is not a reason to stay home.
Several other things cause brief visual blackouts, and telling them apart is a job for an exam rather than a checklist. Alongside the vascular causes, the eye-related ones listed for a one-eyed episode include swelling of the optic nerve heads (clinical: papilledema), deposits in the optic nerve head (clinical: optic disc drusen) and intermittent narrowing of the eye's drainage angle (clinical: intermittent angle-closure glaucoma)4. Transient vision loss affecting both eyes raises different possibilities, including cortical or vertebrobasilar causes4. You are not expected to sort this out yourself. Describe exactly what you saw, in which eye, and for how long.
How Amaurosis Fugax Is Diagnosed
A dilated exam looks for evidence that something passed through. The fundus may show Hollenhorst plaques, small bright cholesterol fragments visible inside a retinal artery3. A normal exam is common and does not rule the episode out, since the fragment has often moved on by the time you are seen. Expect dilating drops, blurry near vision for a few hours and light sensitivity, so plan not to drive yourself home from the appointment.
This is the part that finds the source. Carotid ultrasound or Doppler is the recommended first-line imaging study, with CT or MR angiography added particularly when carotid imaging is inconclusive3. Brain imaging such as MRI, together with imaging of the blood vessels such as CT or MR angiography of the head and neck, may be obtained to look for narrowed vessels inside the head, brain ischemia or a previous stroke4. Carotid ultrasound is painless: gel on the neck and a probe, in a short appointment. It measures how narrow the artery is, which decides whether surgery is on the table.
The rest of the workup covers the other likely sources. An ECG should be performed, with Holter monitoring for paroxysmal atrial fibrillation and echocardiography to look for cardiac emboli and valve problems, alongside blood counts, glucose, lipid profile, clotting tests and the inflammatory markers ESR and CRP3. In people over 50, a normal ESR, CRP and blood count together with a normal eye exam and no systemic symptoms make giant cell arteritis unlikely1. That combination is why the blood draw happens the same day.
How It Is Treated and How Another Event Is Prevented
Treatment is aimed at the cause rather than the eye. Antiplatelet medicines given on their own, commonly aspirin or clopidogrel, are among the usual agents; where the clot came from the heart, anticoagulant medicine is indicated instead, and the direct oral anticoagulants are preferred over warfarin except in valvular cases; a statin may be prescribed with the aim of getting LDL cholesterol below 70 mg/dL; and blood pressure treatment targets less than 130/80 mm Hg3. Doses are set by your own team based on your other conditions. Ask what each medicine is for and what would make you stop it, and do not stop one on your own.
If the ultrasound shows a tight narrowing on the side of the affected eye, an operation may be offered. Carotid endarterectomy is recommended for symptomatic patients with 70 to 99 percent carotid artery stenosis3. The surgeon opens the artery and removes the plaque. It is done under anesthesia and usually involves a short hospital stay. Whether it fits you depends on how narrow the artery is, which side it is on, and your general health, so ask for the specific measurement from your scan.
Medicines do a great deal, and daily habits do the rest. Stopping smoking, controlling blood pressure and blood sugar, treating cholesterol and staying active all act on the same plaque that caused the episode. Diabetes, heart disease, smoking, high blood pressure, high cholesterol and cocaine use are the listed risk factors3. None of this undoes what has already built up in an artery. All of it changes what happens next, which is the part still in front of you.
Risks, Recovery and a Realistic Outlook
The numbers are the reason for the urgency. Studies estimate that amaurosis fugax left untreated carries roughly a 10 to 15 in 100 risk of stroke within the first year3. In a US health-record study of 11,297 adults after a blocked retinal artery or an episode of amaurosis fugax, about 14 of every 100 had an ischemic stroke and about 11 of every 100 had a transient ischemic attack within one year, and about 9 of every 100 had one of those events on the same day as the eye event5. After any transient ischemic attack the risk of stroke is about 10 to 15 of every 100 at roughly 3 months, with more than half of those strokes occurring in the first 48 to 72 hours1. The steepest part of that risk is in the first days, which is the window a same-day emergency visit is designed to use.
The episode that clears can be followed by one that does not. Central retinal artery occlusion is a form of acute ischemic stroke caused by blocked blood flow in the main artery of the eye, the treatment window is narrow, and fewer than 20 of every 100 people regain functional vision in that eye6. That is a sobering figure and it is also the argument for acting on the warning while your sight is still coming back. Sudden vision loss that does not clear within a few minutes is a call-911 event.
A great deal, which is the point of the whole workup. The stroke risk quoted earlier has a treated end and an untreated end, and the emergency visit is what moves you toward the treated one. Antiplatelet or anticoagulant medicine, statin treatment and blood pressure control are the standard measures used after this kind of event3. People who undergo carotid endarterectomy for a suitable narrowing have a good prognosis, although their risk of adverse heart events remains3. No one can promise you an individual outcome, and your team can tell you which risks apply to your scans and your heart. Turning up is the step that makes the rest possible.
When to Call for Help and Who You Will See
Do not drive yourself and do not wait to see if it settles. Call 911 for sudden vision loss in one eye that does not clear, face drooping, arm weakness, slurred speech, sudden confusion, sudden severe headache, or trouble walking. A retinal warning event calls for immediate transfer to the nearest emergency department affiliated with a stroke center, with the workup completed within 24 hours1. If you have already been through the workup and it happens again, that is another emergency visit, not a phone call to your clinic in the morning.
Several specialties share this problem. An emergency physician and a stroke neurologist run the acute assessment. A vascular surgeon becomes involved if the carotid artery needs surgery, and a cardiologist if the source is the heart. An ophthalmologist or retina specialist examines the eye and follows it afterward. Your primary care doctor holds the long-term prevention plan. Ask who is coordinating, and ask for a copy of your carotid scan result.
Common Questions About Amaurosis Fugax
Because the returning vision means the blockage moved, not that the source is gone. After any transient ischemic attack, about 10 to 15 of every 100 people have a stroke within roughly 3 months and more than half of those come in the first 48 to 72 hours, so the workup belongs in an emergency department affiliated with a stroke center within 24 hours1. The tests needed are not available in most eye clinics. Going now is what shortens that window.
Briefly, which is part of why it gets ignored. The loss of sight usually lasts seconds to minutes2, and episodes most often run between 2 and 30 minutes3. Anything that lasts longer, or does not clear at all, is a different and more urgent situation. Note the time it started and how long it took to clear, because that detail genuinely helps the team sort out the cause.
It is the eye's version of a warning stroke. The blood supply to the retina is briefly cut off and then restored, so the eye itself usually recovers, although brain imaging afterward sometimes shows changes. Central retinal artery occlusion, in which the blockage does not clear, is itself a form of acute ischemic stroke6. Doctors treat the transient version with the same seriousness as a brain warning stroke, because the underlying plumbing problem and the risk that follows are the same.
It can be, and that is a diagnosis made after the dangerous causes are excluded rather than instead of checking. Migraine is one of the neurologic causes of transient vision loss, and where both eyes are affected, migraine with aura sits alongside reduced flow in the arteries at the back of the neck (clinical: vertebrobasilar insufficiency) among the possibilities4. Because diabetes, heart disease, smoking, high blood pressure, high cholesterol and older age are the recognized risk factors, the vascular causes get checked first when any of those apply3.
It is inflammation of medium and large arteries, and your team asks about jaw ache while chewing because that symptom shifts the suspicion toward it. Giant cell arteritis should be suspected in anyone older than 60 with repeated episodes of transient vision loss3. In people over 50 the screening tests are ESR, CRP and a blood count, and normal results with a normal eye exam and no systemic symptoms make it unlikely1. That is why the blood tests are drawn urgently rather than booked for next week.
Only if the scan shows a tight enough narrowing on the relevant side. Carotid endarterectomy is recommended for symptomatic patients with 70 to 99 percent carotid stenosis3. Many people have milder narrowing, or none, and are treated with medicines and risk-factor control instead. Ask for the actual percentage from your ultrasound report and which side it was on, because that single number drives most of the decision.
More Questions About Risk, Prevention and Follow-Up
Yes, and a repeat episode is treated as a fresh emergency. The event to guard against is the blockage that does not clear. A central retinal artery occlusion is itself a warning sign of other vascular issues, so ongoing follow-up is important for preventing a future stroke or heart attack6. Staying on your medicines is a central part of lowering that risk, along with blood pressure, cholesterol, blood sugar and stopping smoking. If an episode happens again, note the eye and the duration and go straight back to an emergency department.
Not from the episode itself, since the vision returns. The concern is the event that does not clear. In central retinal artery occlusion the treatment window is narrow and fewer than 20 of every 100 people regain functional vision in the affected eye6. That is why speed matters so much for sudden loss that persists. For the transient version, the realistic outlook for the eye is good, and the attention goes to protecting the brain.
Usually a combination rather than one person. Your primary care doctor or a stroke neurologist manages medicines, blood pressure and cholesterol. A vascular surgeon reviews the carotid artery if it was narrowed, and a cardiologist if a heart rhythm problem was found. An eye doctor rechecks the retina. Ask for the results of the carotid scan, the heart monitor and the blood tests in writing, and bring them to each appointment.
- What did my carotid scan show, and what was the exact percentage of narrowing?
- Which side was affected, and does it match the eye involved?
- Did my heart monitor or echocardiogram find a source?
- What were my ESR and CRP results?
- What is each of my new medicines for, and how long do I stay on it?
- Am I a candidate for carotid surgery, and what would that decision hinge on?
- What are my blood pressure and cholesterol targets?
- What exactly should make me call 911 rather than your office?
- EyeNet Magazine, American Academy of Ophthalmology, summarizing transient-ischemic-attack outcome cohorts and retinal-ischemia imaging series (2023). Retinal TIAs: A Medical Emergency.
- Cleveland Clinic, patient health library (2024). Amaurosis Fugax.
- StatPearls, NCBI Bookshelf NBK470528, peer-reviewed clinical reference chapter (2025). Amaurosis Fugax (StatPearls).
- EyeWiki, American Academy of Ophthalmology (2025). Amaurosis Fugax (Transient Vision Loss) (EyeWiki).
- Ophthalmology Retina (peer-reviewed), electronic-health-record analysis of 11,297 adults with an incident ischemic ocular event (retinal artery occlusion or amaurosis fugax) (2026). Stroke Risk after Ischemic Ocular Events: Insights from an Electronic Health Record Database.
- American Heart Association newsroom, reporting the AHA/ASA scientific statement Management of Central Retinal Artery Occlusion (2021). Stroke affecting the eye requires immediate treatment, can signal future vascular events (news release on the AHA scientific statement, Stroke 2021;52:e282-e294).