Acute macular neuroretinopathy (AMN) is a rare condition in which you suddenly develop blurry or small blind spots in one or both eyes.
While the spots may interfere with your vision in the areas they affect, they don't block vision there or cause blindness. They're caused by lesions in the deep layers of your eye that can only be seen using imaging technology.
The condition was first described in 1975. But doctors are still unsure exactly what causes these spots to appear or how to treat them.
AMN affects less than 1 in 1 million people, according to recorded cases. But doctors and researchers say the actual number may be higher. That's because the condition isn't well-known and can be hard to diagnose.
Here’s what doctors know about AMN, what may cause it, how doctors diagnose it, and what you can expect if you or someone you know has it:
Symptoms of Acute Macular Neuroretinopathy
The most common symptom of AMN is blurry or blind spots in your eye – known in the medical community as paracentral scotomas – that are just off the center of your direct line of vision. Sometimes, multiple spots appear over a few days.
Some people also report:
- Flashes that appear and quickly disappear
- Floaters, small dark spots or lines that float across your vision
- Distortion, in which straight lines looked curved
Some people develop these blind spots or flashes a day or two after having flu-like symptoms.
In most cases, ACM only affects one eye. But one study that looked at 101 cases between 1975 and 2014 found that 45% of people had cases that involved both eyes.
Along with these blurry or blind spots, doctors can see brownish-red lesions on your retina. (The retina, a layer of tissue at the back of your eye, helps turn light into signals for your brain that create the images you see.) These lesions can take days or months to appear after you notice the spots in your vision.
If you have ACM, an eye exam will also sometimes reveal faint retinal hemorrhages. These are signs of bleeding in blood vessels deep in the eye.
What Causes Acute Macular Neuroretinopathy?
Doctors are unsure what causes the lesions and blind spots of AMN. But some cases have been linked to various illnesses, birth control pills, and caffeine. Up to half of people with AMN were reported to have had flu-like illnesses before their diagnosis.
Right now, researchers believe that the body's response to some viruses and substances may trigger issues with your circulatory (vascular) system and blood flow. This results in less blood supply to some parts of your body, including the eye and retina.
Things that have been linked to reported cases of AMN include:
- Fever and other flu-like symptoms
- Sinus infections and medications
- COVID infections and vaccinations
- Birth control pills
- Intravenous (IV) contrast, used during imaging tests like CAT scans
- IV ephedrine, which may be used to treat low blood pressure during or after surgery
- Cocaine use
While rare, there have been some reported cases of people getting AMN and other eye conditions after getting the COVID-19 vaccine. Researchers say it is unclear whether the vaccine or COVID-19 infection may have triggered the eye issues. They think the body’s immune response to the vaccine or to the infection may be involved.
Researchers are unsure whether an increase in cases of AMN during the pandemic might be due to COVID-19 and its vaccines themselves, or simply to the fact that so many people were getting infections and vaccinations within a short time span.
Who Gets Acute Macular Neuroretinopathy?
AMN has most often been reported in white women who are young to middle-aged, particularly those in their 30s. But cases reported during the COVID-19 pandemic were often in people older than that. In most cases, people with AMN have no history of eye disease.
How Is AMN Diagnosed?
Your doctor will ask about your medical history and recent health and do an eye exam. Part of this exam will include using imaging technology to view the back of your eye and retina.
They may use infrared, red-free photography, or optical coherence tomography (OCT) to take pictures of the different layers in your eye, including the retina. These imaging tests allow them to look for lesions and other issues in the eyes that may be causing your symptoms.
What Are Treatment Options for Acute Macular Neuroretinopathy?
Unfortunately, doctors don't know of any medicines or treatments to help with the condition. In some cases, the spots improve on their own over several months. In other cases, the spots remain.
But, because the blurry or blind spots are not in the center of the eye, the disease doesn't cause major vision loss.
Your doctor may suggest follow-up appointments so they can track the status of the disease.