Retinal migraine is an eye condition that causes brief attacks of blindness or visual problems like flashing lights in one eye.
These episodes can be frightening, but in most cases they're harmless and short-lived, and eyesight goes back to normal afterwards.
Some people get a retinal migraine every few months, although the frequency can vary.
A retinal migraine is a distinct condition that should not be confused with headache-type migraines. It is sometimes referred to as an 'ocular migraine'.
What are the symptoms?
Loss of vision
Some people with retinal migraine will completely lose their vision in one eye for a short period of time, typically 10-20 minutes.
Others will only partially lose their sight in one eye – vision may slowly become blurred or dimmed, or there may be flashes of light.
Some people see a mosaic-like pattern of blank spots ('scotomas'), which enlarge to cause total loss of vision.
Vision then gradually returns. It's unusual for an episode to last longer than an hour.
In almost all cases, the same eye is affected every time.
Not everyone with retinal migraine will develop a headache. If they do, it may happen before, during or after the vision attack.
What should I do if my sight goes?
If your eyesight suddenly deteriorates, make an emergency appointment to see an optometrist (an optician trained to recognise eye abnormalities and signs of eye disease) or your doctor.
It is important to see an optometrist or medical doctor urgently if you suddenly lose your eyesight, particularly if it occurs for the first time. There are other more serious causes of sight loss that doctors will want to rule out.
What's the cause of retinal migraine?
Retinal migraine is caused by the blood vessels to the eye suddenly constricting (narrowing), reducing the blood flow to the eye.
It may be triggered by:
- high blood pressure
- hormonal birth control pills
- bending over
- high altitude
- low blood sugar
- excessive heat
Afterwards, the blood vessels relax, blood flow resumes and sight returns. Usually there are no abnormalities within the eye and permanent damage to the eye is rare (see Possible complications).
Who is affected?
Retinal migraine can affect both adults and children.
It tends to be more common in:
- people aged under 40
- people with a personal or family history of migraines or other headaches
- people with an underlying disease such as lupus, hardening of the arteries, sickle cell disease, epilepsy, antiphospholipid syndrome (a disorder of the immune system that causes an increased risk of blood clots) and giant cell arteritis (inflammation of the arteries in the head and neck)
How is retinal migraine diagnosed?
If you manage to see a doctor or optometrist during an attack, they may be able to see the decreased blood flow to your eye using an instrument called an ophthalmoscope. In this case, the doctor or optometrist may be able to make a confident diagnosis of retinal migraine.
But attacks are usually brief, so it's more likely you'll be diagnosed based on an account of your symptoms.
You may be referred to an eye specialist for tests to rule out other more serious eye diseases or stroke.
Can retinal migraine be treated?
Treatment for retinal migraine usually just involves taking pain relief for any headaches and reducing exposure to anything that might be triggering the retinal migraine (see the list of possible triggers).
If considered necessary, a medicine such as as a beta-blocker (propranolol), verapamil or nifedipine may be prescribed.
Aspirin or nifedipine may help prevent exercise-induced attacks.
There's a small risk that the reduced blood flow may damage the retina (thin layer at the back of the eye) and blood vessels of the eye. This will be monitored in your follow-up appointments. Permanent vision loss is rare.