Sudden vision loss in one eye may be a sign of Central Retinal Artery Occlusion (CRAO), commonly referred to as eye stroke. Like a stroke in the brain, it is a medical emergency and must be diagnosed and treated as quickly as possible to prevent irreversible loss of vision.

It is estimated that about 12,000 people suffer an eye stroke every year. Risk factors include smoking, cardiovascular disease, diabetes, high cholesterol, high blood pressure, and narrowing of the carotid or neck arteries, but it can affect anyone, particularly those over 60 years of age.

In this Q&A, Richard B. Rosen, MD, Chief of Retina Service at Mount Sinai Health System and Vice Chair and Director of Ophthalmology Research at the New York Eye and Ear Infirmary of Mount Sinai (NYEE), explains Mount Sinai’s unique approach in this area, and how getting to a hospital as soon as possible can help doctors diagnose your problem and restore your vision.

“Eye stroke must be addressed immediately to prevent permanent vision loss. If you wake up with vision loss, get to the emergency room as quickly as possible, don’t put it off until after breakfast,” says Dr. Rosen, who is also Professor of Ophthalmology at the Icahn School of Medicine at Mount Sinai. “That will enable doctors at Mount Sinai to restore your vision if it’s an eye stroke and, if it’s something else, we can send you to an ophthalmologist. Not all hospital emergency departments have the specialized equipment and procedures we have in place to ensure patients get treatment in an expedited fashion.”

What is an eye stroke?

Blood vessels supply oxygen and nutrients to the retina, the light-sensitive tissue in the back of the eye. The retina transfers visual signals to the brain, which enable us to see images clearly. If an artery is blocked, it can deprive the retina of oxygen and can cause the retinal nerve cells to die unless blood flow is quickly restored.

What are the symptoms?

There are four key symptoms of eye stroke. They are:

• Severe blurring or complete loss of vision may occur suddenly, and almost always only in one eye. It is often described as a curtain crossing over the vision, or it may appear totally black or white.
• An eye stroke is painless, which often makes it different from other causes of vision loss.
• Blurring may worsen over a few minutes and sometimes improve suddenly.
• Painless vision loss may also be a sign of a stroke in the brain, and patients experiencing eye stroke are at risk for brain stroke.

Why is it so important to act quickly?

Anyone experiencing these symptoms must get immediate medical treatment, even if symptoms seem to improve. Even temporary vision loss might indicate an increased risk of stroke or future vision loss. The Emergency Departments at several Mount Sinai hospitals are equipped to diagnose (or rule out) and treat eye stroke quickly: NYEE, The Mount Sinai Hospital, Mount Sinai West, and Mount Sinai Queens. Treatment must be administered within 6-12 hours (ideally in less than six hours) to prevent irreversible vision loss. A team of Mount Sinai retina specialists is available 24/7 to make a diagnosis using non-invasive imaging. If a retinal artery occlusion is not the cause, doctors can address your problem or connect you with the appropriate eye doctor.

How is eye stroke treated?

To dissolve the clot, an interventional radiologist administers an injection of tissue plasminogen activator (tPA), a clot-busting drug, directly into the blocked artery. There is a small window to intervene. To prevent permanent blindness, blood flow to the retina must be restored within six to 12 hours, and the sooner blood flow can be restored the more vision can be saved. TPA represents the latest advancement in eye stroke treatment, an area that NYEE has been actively researching.

 How do doctors at Mount Sinai diagnose eye stroke?

NYEE, part of Mount Sinai Health System, has developed an eye stroke protocol, working with the Mount Sinai Stroke Center, that combines the expertise of ophthalmologists, neuroradiologists, neurologists, and emergency department faculty. Trained staff are available 24/7 to take images of the eye. The images are sent to one of NYEE’s retina specialists to make a rapid diagnosis. If an eye stroke is confirmed, the Mount Sinai Stroke Service begins treatment immediately to save the patient’s sight.

Mount Sinai doctors accurately diagnose eye stroke using advanced optical coherence tomography (OCT) systems, a technology that most hospitals do not have available at the point of care. The non-invasive system detects swelling by using infrared light to produce digital images of the retina at very high resolution. Using this system, what might take one or two hours in some facilities, can now be done in about 15 minutes at Mount Sinai, thereby saving valuable time.