Exophoria is when covering up one of your eyes makes it drift outward, away from your nose and your other eye. It's a type of strabismus. You could have it without knowing. But it may cause symptoms during tasks like reading that require your eyes to converge, or move inward, to focus on close objects.
Small misalignments in your eyes (when they’re slightly out of position) are normal and no big deal. But bigger misalignments can cause more severe symptoms and vision issues. One study found about 1 in 10 people have exophoria. It can often be improved or corrected with prescription glasses and, if needed, eye muscle exercises.
The key in exophoria is that your eyes don't drift outward spontaneously or on their own, says Aaron Miller, MD, clinical spokesperson for the American Academy of Ophthalmology and a pediatric ophthalmologist at Houston Eye Associates in Houston, TX.
Exophoria vs. exotropia
If your exophoria gets worse, one of your eyes could start to drift so far out of coordination that your brain can't blend the two images. You may sometimes see double. Or your eye may start to drift off and on, even when you don't have an eye covered up. When exophoria worsens, it's called a decompensated exophoria, which is a type of exotropia.
"Exophoria can be a precursor to exotropia," Miller says. "The difference is, an exophoria is when an eye drifts out but not spontaneously. Exophoria requires an active disruption of fusion. An intermittent exotropia is when an eye drifts out without an active disruption."
What Are the Symptoms of Exophoria?
Exophoria symptoms may start early in life. They may affect you while you're looking at things close to your eyes, such as while reading, writing, or using a computer. If your eyes tend to drift, you may have to work harder to keep them focused.
Symptoms can include:
- Headaches
- Sore eyes
- Trouble reading
- Double vision
- Irritability
- Poor performance in sports
- Squinting or closing one eye in bright light
- Tiredness
- Trouble focusing in school
Symptoms could get worse over time.
Marcia Hutcheon, MD, a pediatric ophthalmologist and adult strabismus specialist in Rockville, MD, says she checks for issues with eye alignment during routine eye exams. When she notices exophoria in a child or adult, she asks if they get headaches or have any eye fatigue.
"I don't make a big deal about it because I don't want them looking for problems," she says. "But sometimes people who have an exophoria do get a lot of trouble reading because they get headaches, their eyes get tired, they might see double for a moment." They may need prescription glasses, especially for near work.
What Are Similar Conditions to Exophoria?
Similar eye issues also make your eyes drift out of alignment. Some have similar names. All fall under a condition called strabismus, which means your eyes are misaligned. Misalignment may happen only sometimes or constantly. Other types of strabismus differ from exophoria in their intensity and when they happen. They also differ in terms of how your eyes move out of alignment. You may have more than one of these at the same time.
Exotropia. Exotropia causes your eyes to drift outward like exophoria. With exotropia, the drifting happens more often and more noticeably. Untreated exophoria may worsen into exotropia. Exotropia may happen only sometimes during certain situations. It may happen more often if it runs in your family, if you've recently had eye surgery, or if you have other vision problems.
Divergence excess. This is when your eye drifts out when you're looking at objects far away. Your eyes split paths (diverge) farther than they're supposed to.
Convergence insufficiency. This is when your eye drifts out when you're looking at objects very close to your face. Your eyes can't properly align together or converge. You may have blurred or double vision.
Esophoria. Esophoria is when your eye drifts inwards towards your nose instead of outwards. This can make you look like your eyes are crossed. Like exophoria, esophoria symptoms appear when you're looking at something close up or when you cover one eye.
Hypertropia. In hypertropia, one of your eyes will have a tendency to drift upward.
Hypotropia. In hypotropia, one of your eyes will have a tendency to drift downward.
Lazy eye (amblyopia). Like exophoria, a lazy eye causes one eye to drift outward regularly. Amblyopia has more to do with the overall communication between your eye and brain than with specific visual triggers such as reading. With amblyopia, your brain relies more often on one eye, which can weaken muscles in your other eye and may lead to vision loss.
Children with exophoria may be misdiagnosed with attention deficit hyperactivity disorder (ADHD), learning disabilities, or dyslexia. These conditions sometimes have similar symptoms, such as trouble reading and concentrating.
How Is Exophoria Diagnosed?
Exophoria can be diagnosed with an eye exam. Your eye doctor will ask about your symptoms. A strabismus specialist is the most common provider who diagnoses exophoria, Miller says.
To find the problems with your eye coordination or alignment, they'll cover one of your eyes slowly or quickly. They'll observe your eye movements during the process. They may put a prism near your eye to see if it improves your vision.
School-offered eye exams don't always test for exophoria and other eye coordination problems. If you think your child may have exophoria, visit a vision specialist's office to get a full exam.
What Causes Exophoria?
Experts aren't sure what causes exophoria. Likely factors include eye muscle weakness, nervous system problems, and the size and shape of your eye. Close-up activities can also put extra strain on your eyes and may lead to exophoria.
How Is Exophoria Treated?
You don't always need treatment for exophoria. But if you have symptoms, they can usually be managed with treatments, such as:
Eye exercises. You may have to physically train your eyes to move in coordination with games and other tools. Some of these exercises can be done at home. One example is a pencil push-up. With this exercise, you move a pencil towards your face from arm's length and try to avoid seeing double as you look at it.
Other exercises can work better when they take place in a professional vision care office. A specialist can observe you while you do the exercises. They can keep track of your progress.
Hutcheon makes exercises tougher by having you do convergence exercises while looking through a prism. It doesn't take long, but you need to practice regularly to see improvements.
"I recommend spending five minutes once or twice a day doing these convergence exercises for two weeks," Hutcheon says. "If you don't see any improvement, come back in."
Glasses. You can get special glasses that have prisms in the lenses. They can help reverse the outward eye movement of exophoria and lessen eye strain. Prism lenses ease symptoms, but they don't fully fix exophoria.
Hutcheon says she finds prism glasses especially helpful when older adults struggle with convergence exercises.
Addressing other issues. Tackling any other issues you have with your eyes may also help with your exophoria.
"For any type of strabismus, the first step is obtaining an accurate refraction (glasses prescription)," Miller says. "Anything that disrupts the clarity of vision in a patient can lead to strabismus, such as an exophoria or intermittent exotropia. Glasses can help an individual to 'control' their eye alignment issue better by introducing better visual clarity. This improved clarity will help the brain's binocular system work better in maintaining fusion and better eye alignment."
Botox. This drug interferes with nerve signals that control your muscles. Botox shots in strategic places on your body may help ease severe exophoria.
Surgery. Some procedures are done to weaken your muscles that rotate your eyes outward. These may be done in extreme cases of exophoria, when other treatments don't work.
Can Exophoria Be Prevented?
Exophoria is common, and there's no foolproof way to keep you from having it. An exophoria is less likely to get worse or cause problems if you take good care of your eyes. See an ophthalmologist regularly for eye exams to catch any issues early.
"Anything that disrupts the visual clarity can cause exophoria," Miller says. "Examples include dry eyes, cataracts, glaucoma, and retinal diseases. The best way to prevent exophoria is to have a thorough eye examination by your ophthalmologist to identify and possibly treat these issues."
When to See a Doctor
If you think you're having problems with your vision, it's always a good idea to see an eye doctor. While exophoria isn't usually a problem, sometimes it may get worse. It may turn into intermittent exotropia or give you headaches, eye strain, or double vision. Miller suggests seeing your regular eye doctor first. Ask them if you should see a strabismus specialist.
"It is best to have a full eye exam by your ophthalmologist prior to seeking the opinion of a strabismus specialist, as many causes of strabismus are secondary to the most common causes of reduced vision, such as dry eyes and cataracts," Miller says. "Addressing these underlying issues first will often help resolve an intermittent exotropia and return it to the level of exophoria."
Takeaways
Exophoria is when covering up one of your eyes makes it drift outward, away from your nose and your other eye. Some misalignments in your eyes are normal and don't cause problems. But bigger misalignments can cause more severe symptoms and vision issues. Many eye doctors check for this condition in routine eye exams of children and adults. See an eye doctor if you're having any problems you think may be related to your eyes.
Exophoria FAQs
How do you test for exophoria?
Eye doctors will cover one eye and then the other to see if your covered eye tends to drift outward.
Can you cure exophoria naturally?
Exophoria won't just go away by itself. But you can do eye exercises to strengthen your eye muscles and control your exophoria.
How long does exophoria last?
Exophoria often starts in childhood and usually lasts throughout your life.
Will glasses fix exophoria?
Glasses to correct your vision may help with your exophoria. In rare cases, prism glasses may help when exophoria causes trouble with reading or other tasks.
