An Overview of Retinal Migraines

Retinal migraine is a rare type of migraine characterized by changes in vision that are monocular—that is, affecting only one eye. Usually, these symptoms precede a headache, but not always.

Some practitioners use the term ocular migraine to refer to retinal migraine, but strictly speaking, the retinal migraine is one of two subtypes of ocular migraine. The other type of ocular migraine is migraine with aura, in which the visual disturbances that come before head pain affect both eyes.

Proper diagnosis of retinal migraine is important, as a vision problem that affects only one eye can be a symptom of a condition that's considerably more serious, such as stroke or a detached retina.

Once you're diagnosed with retinal migraines, managing the condition usually focuses on preventing episodes with lifestyle changes, identifying and avoiding triggers and, if necessary, some of the same prophylactic medications used to prevent "regular" migraine headaches (the ones with auras).

A number of specific changes in vision have been reported by people who've had retinal migraines. In one of the few studies looking at these specific symptoms, these included:

• Complete loss of eyesight (50 percent of subjects)
• Blurred vision (20 percent)
• Scotoma, or blind spot (13 percent)
• Partial loss of vision (12 percent
• Dimming of vision (7 percent)

Some people experience scintillations, or flashes of light.

Remember, these symptoms affect only one eye. This means if you were to close the eye that's affected, your vision out of the other eye would be normal. By contrast, visual changes resulting from migraine with aura would be apparent whichever eye is open.

Most of the time, retinal migraine symptoms are relatively short-lived, lasting between five and 20 minutes, although visual disturbances can last for up to an hour before headache and other migraine symptoms set in. About 75 percent of the time, migraine pain will develop on the same side of the head as the affected eye.

Rarely, a visual disturbance will last longer, perhaps even persisting for the duration of the headache or beyond. Some experts believe that partial or complete vision loss resulting from retinal migraine can become permanent, but this is controversial and hasn't been proven. Research suggests, in fact, that permanent vision loss in one eye is likely to be caused by hemianopia (injury to the brain) rather than retinal migraine.

Although the exact physiology of retinal migraine is unknown, one theory is that it may result from vasospasm, a narrowing of vessels that supply blood to the retina or that are part of the ciliary body of the eye. (The ciliary body produces fluid and also contains the muscle that changes the shape of the lens of the eye in order to focus on an object that's close-up.)

Whatever the mechanism, like all types of migraine headaches, retinal migraines tend to be brought on by specific triggers such as stress, high blood pressure, smoking, and more.

People believed to be at increased risk of retinal migraine headaches include those who:

• Are in their 20s or 30s—in particular women, due to hormonal changes related to the menstrual cycle
• Have a history of other types of migraine
• Have a family history of migraine headache
• Have lupus, atherosclerosis, or sickle cell disease

No designated tests can diagnose retinal migraines. Doctors look at your medical history and symptoms, perform a physical exam, and, in most cases, order tests to rule out other potential causes of monocular vision loss. For example, a brain scan may be used to see whether you've had a stroke, while blood tests or urinalysis may be ordered to check for lupus or sickle cell anemia.

To be diagnosed as retinal migraine, the visual aura must involve only one eye, be temporary, and meet at least two of the following criteria:

• Spreads gradually over the course of five minutes or more
• Lasts for five minutes up to an hour
• Is accompanied or followed (within an hour) by a headache

The focus of managing retinal migraines is on prevention rather than using abortive medications to stop them once they occur. This approach begins with identifying triggers that may be responsible for bringing on symptoms. Keeping a written log of when retinal migraines occur and what you were doing just prior to vision changes is the easiest and most straightforward way to do this.

Once you know what is likely to cause your retinal migraines, you may be able to keep them at bay by avoiding those triggers—quitting smoking, for example, or switching to a non-hormonal contraceptive.

If you need preventive medication, your doctor may prescribe a so-called oral migraine prevention medication (OMPM), such as:

• A calcium channel blocker such as Calan (verapamil) or Procardia (nifedipine), which primarily are used to treat high blood pressure
• Amitriptyline (a tricyclic antidepressant)
• Valproaic acid (Depakote, Depacon, and others) and Topamax (topiramate), medications that are commonly used to prevent seizures

To deal with head pain and other symptoms that follow the visual disturbances of retinal migraine, you can turn to pain relievers, including Tylenol (acetaminophen) and non-steroidal anti-inflammatory drugs (NSAIDs) such as Advil (ibuprofen).

Until they subside on their own, the AMF suggests taking measures to relieve the visual symptoms caused by retinal migraines.