A stroke happens when something blocks blood flow to the brain. Similarly, the term “eye stroke” is used when blood flow to the retina or optic nerve is suddenly disrupted, causing vision loss.
“If you experience sudden and painless loss of vision in one eye, it may be an eye stroke,” explains Poonam Bansal, M.D., a neurologist at Henry Ford Health. “Because several serious conditions can cause sudden vision loss, it should be treated as a medical emergency, and you should go straight to the emergency room.”
Learn about the different types of eye strokes, who’s at high risk and how to protect your vision.
Types of Eye Strokes
“Eye strokes can be divided into two major categories depending on whether the retina or optic nerve is affected,” says Dr. Bansal. “A disruption of blood supply to either can cause an eye stroke.”
The retina is the light-sensitive area of the eye that relays signals to the optic nerve. Those signals tell the brain how to process what you’re seeing. When blood flow is diminished or cut off from the retina or the optic nerve, you can experience a sudden change of vision. This could be blurred vision or a complete loss of eyesight in one eye.
What Is a Central Retinal Artery Occlusion (CRAO)?
An eye stroke that impacts the retina is called a central retinal artery occlusion (CRAO). It happens when a clot goes into the main blood vessel or one of the smaller branches of the retinal artery. These vessels carry blood to the retina.
“A CRAO can also be a warning sign of vascular disease and can increase your risk of brain stroke or other cardiovascular events,” says Dr. Bansal. “People with CRAO should have a full stroke workup.”
What Is a Nonarteritic Anterior Ischemic Optic Neuropathy (NAION)?
A nonarteritic anterior ischemic optic neuropathy (NAION) is the more common type of eye stroke. It occurs when blood supply to the optic nerve is reduced.
Unlike a CRAO, an NAION typically doesn’t require an emergency stroke evaluation. “But patients should still be evaluated for underlying risk factors, including high blood pressure, diabetes, high cholesterol and obstructive sleep apnea,” explains Dr. Bansal.
NAION frequently occurs right when you wake up. The reason for that isn’t entirely understood. One possible explanation is a condition called nocturnal hypotension (a drop in blood pressure during sleep). It may cause reduced blood flow to the optic nerve.
Why Early Eye Stroke Treatment Is Essential
As with a brain stroke, timing of treatment can be key to better eye stroke outcomes. “If you have any sudden vision changes, blurriness or loss of vision, you should go to the ER,” says Dr. Bansal. “Time is vision. You need to be evaluated as quickly as possible at an emergency department or stroke center.”
This is especially true if the eye stroke you’re experiencing turns out to be a CRAO, she adds. In some cases, doctors may consider clot-busting medication for patients who get care within 4.5 hours of symptom onset.
Eye Care at Henry Ford
“We don’t currently have medication that reverses an NAION,” says Dr. Bansal. “But it’s still important to get evaluated and diagnosed promptly after any loss of vision.”
Eye Stroke Prevention
Eye strokes and brain strokes share many similar risk factors. These include:
- Diabetes
- High blood pressure
- High cholesterol
- Obesity
- Sleep apnea
- Smoking
For NAION, the anatomy of the optic nerve is also an important risk factor.
The best way to help prevent eye strokes is to lead a more heart-healthy lifestyle. “Modifying your risk factors is important for prevention,” says Dr. Bansal. If you’ve already experienced an eye stroke in one eye, this becomes even more important.
Lifestyle changes that can help prevent an eye stroke include:
- Eating a heart-healthy diet (such as the Mediterranean diet)
- Exercising regularly
- Maintaining a healthy weight
- Taking cholesterol or blood pressure medications if needed
- Quitting smoking
Keeping your eyes healthy is an important part of your overall well-being. And if you notice changes, seek medical care. “Don’t take vision loss lightly,” warns Dr. Bansal. “Even if the vision change is painless, it can represent a medical emergency and should be evaluated as soon as possible.”
Reviewed by Poonam Bansal, M.D., a neurologist and neuro-ophthalmologist who sees patients at Henry Ford Hospital in Detroit, Henry Ford Ophthalmology - Optimeyes Troy and Henry Ford Ophthalmology - Optimeyes West Bloomfield.
