Double vision isn’t something to ignore. While typically temporary, it may signal a serious problem, such as a brain aneurysm or stroke.
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“Some people get fleeting double vision that goes away,” says neuro-ophthalmologist Lisa Lystad, MD. “But if double vision stays with you for a couple of hours, call your primary care physician or eye doctor, or go to the ER.”
Your doctor can determine what type of double vision (diplopia) you have and what’s causing it before determining the best way to treat it. “Fortunately, while double vision can be frightening, it is treatable,” she says.
When you have double vision, you get two images when you look at a single object. The images may appear one on top of the other or side-by-side (or both ways).
Double vision can be either monocular or binocular.
Monocular double vision
Monocular double vision affects one eye, and the problem originates in the eye itself.
“It is seen using only one eye at a time,” says Dr. Lystad. “If you have double vision in the right eye and cover your left eye, you still see double.”
The problem originates in the eye itself. Many eye-related issues — including the need for glasses (for astigmatism, for instance), dry eyes, cataracts, and retinal disease in the macula — can cause monocular double vision.
“Double vision in one eye is caused by an eyeball problem, not a neurologic or brain problem,” she notes.
Binocular double vision
In binocular double vision, the eyes are not visually aligned. Both the images you see are clear. If you cover either eye, the double vision always goes away.
Binocular double vision can stem from a wide variety of problems, some of them originating in the brain, which may be quite serious.
Whether double vision affects one or both eyes, ophthalmologists must search for the root cause, which can be a problem with the brain, the nerves, the muscles or the lens.
A problem with the brain
Tumors, trauma, aneurysms, stroke or autoimmune diseases involving the brain can cause double vision.
“Normally, your brain says to look up. It then organizes that information and sends it down nerves that connect to your eye muscles. The nerves communicate with the eye muscles to make them move, and so you look up,” says Dr. Lystad.
“A problem occurring anywhere along that pathway can cause double vision.”
Treating the underlying disease may help restore your vision. Another option involves using prism lenses to help the eyes align better.
“When someone has problems walking, you give them a cane to help with their balance,” says Dr. Lystad. “We use prisms the same way. The eye muscles still move, but prisms help stabilize the movement.”
While prism lenses don’t cure double vision, they can help you get back to everyday activities.
If prisms don’t help, Dr. Lystad recommends wearing an eye patch, but not 24/7. “We want the bad eye to actively move around for two to three hours a day, even up to 50 percent of the time,” she says.
A problem with the nerves
Diseases such as diabetes, hypertension, high cholesterol and multiple sclerosis can damage the nerves that stimulate the eye muscles, leading to double vision.
Your doctor will focus on treating or better controlling the underlying disease. Double vision related to neurological or vascular diseases typically improves with treatment.
A problem with the muscles
When one eye muscle is weaker than the other, you can start seeing double. Thyroid disorders and myasthenia gravis (an autoimmune illness) can cause this problem.
For patients with thyroid issues, surgery can help to reposition the eye muscles. It’s important to stabilize any eye movement abnormality prior to surgery, possibly through steroid treatment or prism therapy, she notes.
A problem with the lens
A cataract (clouding of the eye’s lens) can decrease your vision and cause you to see double. Surgery to remove the cataract can help to fix the problem.
If astigmatism is the culprit, wearing special contact lenses or glasses should help, Dr. Lystad says.
Don’t hesitate to seek help
Whenever double vision persists, seek medical attention immediately, she stresses.
Then follow up with regular eye exams. Ophthalmologists recommend annual exams for those under age 18 and over age 65, and exams every two years for those in between.