Ocular migraines cause vision loss or blindness lasting less than an hour, along with or following a migraine headache. Experts sometimes call these episodes "retinal," "ophthalmic," or "monocular" (meaning one eye) migraines.
This problem is rare. It affects about one out of every 200 people who have migraines. Some research suggests that in many cases, symptoms of ocular migraine are actually due to other problems.
When someone has a basilar migraine, there is a disturbance at the brainstem or base of the brain. Even before the migraine headache begins, the person may experience an ''aura,'' a cluster of sensations such as dizziness, double vision, and lack of coordination. An aura is a neurological phenomenon that occurs about 10 minutes to 45 minutes before the headache starts.
Basilar migraines are known by several different names:
Diagnosing ocular migraine requires a health care professional to rule out other conditions that can cause similar symptoms. Being able to describe the symptoms properly is important for helping your doctor determine whether you actually have an ocular migraine.
Ocular Migraine Symptoms
According to the International Headache Society's definition of this condition -- which it calls retinal migraine -- symptoms include:
Vision problems that affect one eye. These problems include:
Blind spots in your field of vision
Blindness in the eye
Vision loss can be a complication of retinal migraines.
Headache that lasts from four to 72 hours. The headache tends to:
Affect one side of your head
Feel moderately or very painful
Pulsate in intensity
Feel worse when you're physically active
Other symptoms include:
Unusual sensitivity to light or sound
An important symptom is that the vision loss only affects one eye. Many people have trouble identifying the difference between flashing lights or blindness in one side of their vision -- but involving both eyes -- and these symptoms in only one eye.
A regular migraine with an aura, which can involve flashing lights and blind spots in the vision, is a more common problem. This type affects about 20% of people who have migraines. But in these cases, these symptoms usually appear in one side of your field of vision and in both eyes.
Covering one eye and then the other can help you tell if your problem is affecting one eye or both.
Ocular Migraine Causes
Experts aren't sure what causes ocular migraines. Some feel that the problem is related to:
Spasms in blood vessels in the retina, the delicate lining in the back of the eye
Changes that spread across the nerve cells in the retina
People who have these migraines may have a higher risk of developing permanent vision loss in one eye. Experts don't know if preventive treatments for migraines -- such as tricyclic antidepressants or anti-seizure medications -- can help prevent permanent vision loss. However, it's wise to talk to your doctor about your symptoms.
Diagnosing Ocular Migraine
To diagnose ocular migraine, your doctor will ask you about your symptoms and examine your eyes. The doctor will try to rule out other problems that could be causing similar effects. These include:
Amaurosis fugax. This is temporary blindness due to lack of blood flow to the eye. The symptoms can be due to a blockage in an artery leading to the eye.
Spasms in the artery that supplies the retina with blood
Giant cell arteritis. This causes inflammation in blood vessels. It can lead to vision problems and blindness.