Ocular migraines are painless, temporary visual disturbances that can affect one or both eyes. Though they can be frightening, ocular migraines typically are harmless and self-resolve without medication within 20 to 30 minutes.
If an ocular migraine-like vision disturbance is followed by a throbbing, usually one-sided headache, this is called a "migraine with aura" (previously called a classic migraine), and the visual disturbance is referred to as an aura rather than an ocular migraine.
A migraine headache without a visual disturbance preceding it is called a "migraine without aura" (previously called a common migraine).
Migraine auras usually are visual in nature, but they can include disturbances of hearing, speech or smell; progressive numbness or tingling in the face or arms or legs; or generalized weakness.
It's also possible, though less common, for an ocular migraine and a migraine headache to occur simultaneously, causing visual disturbances and unilateral (one-sided) or bilateral (two-sided) head pain at the same time, or for an ocular migraine to follow a migraine headache.
Painless ocular migraines can appear suddenly, creating the sensation of looking through a cracked window. The accompanying visual distortion spreads across the field of vision and usually disappears within 30 minutes.
Ocular Migraine Symptoms
You might see a small, enlarging blind spot (scotoma) in your central vision with bright, flashing or flickering lights (scintillations), or wavy or zig-zag lines surrounding the blind spot. The blind spot usually enlarges and may move across your field of vision.
This entire migraine phenomenon may end in only a few minutes, but usually lasts up to 30 minutes.
About 60 percent of migraine sufferers also experience a "prodrome" that occurs days or weeks before the migraine attack. Symptoms of a migraine prodrome can be subtle and may include changes in mood, cravings for certain foods, or a general feeling of being tired.
What Causes an Ocular Migraine?
Ocular migraines are believed to have the same causes as migraine headaches.
According the the World Health Organization (WHO), migraines "almost certainly" have a genetic basis, and some studies say 70 percent of people who suffer from the disorder have a family history of migraine headaches.
It appears migraines are triggered by activation of a mechanism deep in the brain, which releases inflammatory substances around the nerves and blood vessels of the head and brain. But why this happens and what brings about the spontaneous resolution of an ocular migraine remain unknown.
Imaging studies also have revealed that changes in blood flow to the brain occur during ocular migraines and visual auras, but the underlying cause for these changes is not known.
Migraines most commonly affect adults in their 30s and 40s, but they frequently start at puberty and also can affect children. Women are up to three times more likely than men to have migraines. Though statistics specifically for ocular migraines are unavailable, approximately 15 to 18 percent of women and 6 percent of men in the United States suffer from migraine headaches, according to WHO.
Common migraine "triggers" that can cause a susceptible person to have a migraine attack (including ophthalmic or ocular migraines) include certain foods, such as aged cheeses, caffeinated drinks, red wine, smoked meats, and chocolate. Food additives, such as monosodium glutamate (MSG), and artificial sweeteners also can trigger migraines in some individuals. Here in Calgary, sudden changes in temperatures from Chinooks can also be a trigger.
Other potential migraine triggers include cigarette smoke, perfumes and other strong odors, glaring or flickering lights, lack of sleep and emotional stress.
Ocular Migraine Treatment and Prevention
Because they generally are harmless and typically resolve on their own within a half hour, ocular migraines usually require no treatment.
If you are driving or performing other tasks that require good vision when an ocular migraine occurs, stop what you are doing and relax until your vision returns to normal. (If you are driving, pull off to the side of the road as soon as you can safely do so, and wait for the vision disturbances to completely pass.)
If you experience visual disturbances that are part of a migraine with aura, or you want to prevent future ophthalmic migraines or migraine headache attacks, it's a good idea to see your general physician for an exam and advice.
Also, you should consider having a comprehensive eye exam with an optometrist or ophthalmologist whenever you experience unusual vision symptoms to rule out sight-threatening conditions such as a detached retina, which requires immediate attention.
Your doctor can advise you of the latest medicines for treating migraines, including medicines designed to prevent future attacks. People who experience migraines that last longer than 24 hours or who have more than two migraines per month generally are good candidates for preventive medical treatment.
It's also a good idea to keep a journal of your diet and activities just prior to your episodes of ocular migraine or migraine with aura to see if you can identify possible migraine triggers that you can avoid in the future.
If your ocular migraines or migraine headaches appear to be stress-related, you might be able to reduce the frequency of your migraine attacks without medicine by simply eating healthful meals on a regular basis, avoiding common migraine triggers, getting plenty of sleep and trying stress-busters such as yoga and massage