Visual Disturbances: Related to Migraine or Not?
By: Deborah I. Friedman, MD, MPH
About 25-30% of migraine sufferers have visual aura symptoms. It is often difficult to determine whether or not visual symptoms are related to migraine, or if they are a symptom of a more worrisome problem.
The visual disturbances of migraine generally last less than an hour, most commonly 10-30 minutes. Sometimes they only last seconds. They may or may not be associated with a headache, and some individuals only experience the visual symptoms without headaches. The visual symptoms usually start before the headache but may occur during the headache.
To complicate the issue, migraine may change throughout life. The character of the headache may change, and the visual symptoms may change. The most common pattern is for the headaches to become less severe or even go away, with episodes of visual aura persisting. Some people only experience migraine-related visual symptoms, often without headache, starting at age 50 or later.
Migraine-related visual symptoms are usually seen in BOTH eyes. Sometimes this is hard to determine, as the symptoms may occur only on ONE SIDE of the visual field. Covering one eye, and then the other, helps to figure out whether the symptoms come from the brain (seen by both eyes, often with the eyes closed), or the eye (seen in one eye only)*. The visual symptoms of migraine fall under three general categories: positive symptoms, negative symptoms and altered/distorted vision.
Positive symptoms (seeing something that isn’t really there) include zig-zag lines which often shimmer (in color, or black/silver) and may move across the field of vision, sparkles, dots, stars, spots, squiggles, and “flash bulb” effects. The “classic” migraine visual aura consists of an area that is not well seen, surrounded by shimmering zig-zag lines, that gradually enlarges and then breaks up over a period of 15-30 minutes.
Negative symptoms (part of the vision is missing) are “blind spots”, tunnel vision, complete loss of vision, or loss of all vision to the left or right side.
Distorted or altered visual symptoms are the sensation of looking through water, heat waves, blurred vision, fractured vision (“cracked glass”, mosaic or kaleidoscope effect), loss of color vision, objects appearing too large or small, or objects seeming closer or farther than they really are.
Given the wide variety of visual symptoms that accompany migraine, it is sometimes hard to determine whether one’s symptoms are indeed migraine-related, or due to a more serious problem that warrants medical attention. Causes for concern include:
- New dark spots or floaters in one eye (remember, cover one eye and then the other to be sure that the images are coming from one eye only) that don’t go away are symptoms of a retinal or vitreous detachment. They are generally different than one’s usual visual migraine symptoms and are painless. There may also be flashes of light in the eye and loss of vision. These symptoms require an emergent evaluation and treatment by an ophthalmologist to prevent permanent visual loss.
- New flashes of light in one eye that don’t go away within an hour may also be symptoms of a retinal or vitreous detachment.
- Episodes of transient loss of vision in one eye may be the warning sign of a stroke or inflammation of arteries. The episodes usually last less than 30 minutes and are usually not associated with a headache. They are especially concerning if they begin after age 45. While migraine can cause the same symptoms, it’s best to be safe and see an ophthalmologist, neuro-ophthalmologist or neurologist if this occurs.
- Tunnel vision, loss of one side of the visual field* or episodes of complete blindness without headache may be symptoms of a stroke or mini-stroke. Other neurological symptoms may be present, such as dizziness, imbalance, weakness, numbness, or double vision. The symptoms often begin suddenly and simultaneously. There may or may not be an associated headache.
- When a previously stable pattern of migraine visual symptoms changes dramatically or increases in duration, it’s best to make sure that there is no other cause and see an ophthalmologist, neuro-ophthalmologist or neurologist if this occurs.
* It is sometimes difficult to tell whether or not the visual loss is coming from one eye, or whether it affects ½ of the visual field (arising from the brain). The best way to make the distinction is to note what you are able to see when looking straight ahead with both eyes open. If the right or left side of the world is missing, the problem is arising from the brain. For example, if you look at the clock and are only able to see the numbers from 12:00 – 6:00, the, the left half of the world is missing and the problem is coming from the brain. Covering one eye and then the other eye is also helpful. If the problem is arising from the brain, it won’t make a difference if either eye is covered. If the problem is coming from one eye, there will be a definite difference when viewing from either eye.
Deborah I. Friedman, MD, MPH, Director, Headache and Facial Pain Program University of Texas Southwestern Medical Center Dallas, Texas