What is an ocular migraine? It sounds like a simple question, right? Answering it, unfortunately, isn’t so easy. Not all experts agree on the exact definition, but “ocular migraine” usually refers to two different things involving migraines with vision changes: migraine aura (which isn’t usually serious), and retinal migraine (which can be very serious, but is also exceedingly rare). Here’s what you should know about both.
Roughly one-third of migraine headache sufferers have something called a migraine aura either just before or during the headache. It’s usually a visual disturbance that can look like “colored lights, zig-zagging patterns, dots, and prism effects that tend to shimmer or scintillate and migrate across the visual field,” explains Bradley Katz, MD, a neuro-opthalmologist at the University of Utah’s Moran Eye Center who specializes in treating migraine-related light sensitivity. An aura might last for 20 to 60 minutes, and it tends to begin gradually and then build.
“It’s almost never a formed hallucination, like a cat, dog, or person—it’s typically shapes or squiggles. It can take up as much as half of a person’s visual field and give the person a kind of tunnel vision experience,” says Wade Cooper, DO, director of the University of Michigan’s Headache and Neuropathic Pain Clinic in Ann Arbor.
What happens in the brain during an aura? “In the back of the brain, where we process visual information, there’s a wave of energy. It starts in the way back and slowly moves forward toward the front of the brain. As it moves forward, it gives you too much energy at first—those are the spots and sparkles that you see. After that, because you’ve burned all that energy out, now you’ve got low energy—that’s the dark spot that you see afterward,” says Dr. Cooper.
It’s also possible to develop a migraine aura without having a headache. “That’s far less common. It’s more likely to happen as you mature. Someone might have migraine aura with headache at a younger age and then just the aura as they get older,” says Dr. Cooper.
The triggers for migraine aura are the same as the triggers for migraine headache (certain kinds of lighting, stress, dietary choices, dehydration, lack of sleep, an infection, certain smells, loud sounds, a weather change, intense physical exertion, or certain medications). But how come some migraine sufferers experience auras and others don’t? What’s the underlying cause? “We don’t know. It’s suspected that some people may have a genetic predisposition,” says Dr. Katz.
It should be noted that, though they’re less common, migraine auras can manifest in ways that aren’t visual. “There can be olfactory auras, where you think you smell something bad and chemical-like, but it’s almost like a hallucination because it’s not there and nobody else can smell it. Others can suddenly become confused, have trouble speaking or thinking of words, or experience numbness or tingling on one side of the body—stroke-like symptoms,” says Dr. Katz. But those types of migraine auras wouldn’t be considered “ocular” because they don’t involve the eyes.
The bottom line: Though migraine aura can be frightening to experience, it’s generally not considered a serious condition and it’s often treatable. If you ever experience the symptoms mentioned above, make an appointment with your primary care provider and he or she may either provide treatment or refer you to a specialist, such as a neurologist, for further evaluation and treatment.
A retinal migraine is different from a migraine aura. It’s characterized by temporarily reduced, blurry, or dimmed vision or total blindness in only one eye, which may occur before or during a migraine headache. This happens when the blood vessels to the eye abruptly start narrowing. It typically lasts 10 to 20 minutes, but could last for up to an hour.
A retinal migraine is far less common than a migraine aura. “It’s about as rare as rocking horse manure. You almost never see it,” says Dr. Cooper. A retinal migraine is more likely to occur in women, people under the age of 40, people with a personal or family history of migraines or other headaches, and people with certain underlying medical conditions (such as lupus, epilepsy, sickle cell disease, and a hardening of the arteries).
For those who develop retinal migraines, there are a variety of over-the-counter and prescription medication treatments that can provide relief, including aspirin, beta-blockers, calcium-channel blockers, tricyclic antidepressants, and anti-epileptics.
The important thing to remember is that unlike a migraine aura, a retinal migraine is serious. So if you notice any of the symptoms above, call your doctor immediately because in rare cases, it can damage the retina and blood vessels and lead to vision loss that’s irreversible.