Exophoria is a condition of the eyes. When you have exophoria, there’s a problem with how your eyes coordinate their movements. It occurs when your eyes tend to drift outward or one eye drifts away from the other.

It’s most common in situations where one of your eyes is covered and doesn’t have the same visual stimulation as the other eye. It may also occur when looking at things that are close to your eyes, like when reading.

If exophoria occurs when looking at objects in the distance, it may be called divergence excess (DE).

Exophoria is usually discovered during childhood.

Exophoria and exotropia are closely related. However, they aren’t the same condition.

Exophoria is when one eye drifts outward during uneven visual stimulation or when viewing objects up close. It’s most common when only one eye is covered. In such cases, the covered eye is the one that will drift outward.

Exotropia is a condition in which the eyes drift outward and away from each other during times of equal visual stimulation. It tends to occur regularly.

Exotropia is a form of strabismus. Strabismus is when there’s a deviation of the eyes that you cannot control.

Both exophoria and exotropia are conditions that cause the eyes to drift outward. Both conditions may also be referred to as convergence insufficiency if they occur when you’re using your eyes to see nearby objects.

The underlying cause of exophoria isn’t clearly known. However, the primary issue of exophoria is a weakness in the eye muscles.

This muscle weakness causes difficulty in what is called eye-teaming, or the ability to get the eyes to work together. This generally happens in childhood.

A 2009 study suggests that one cause may be that the non-dominant eye reacts to the stress of visual changes by drifting outward. These visual changes can occur during activities like reading, when the eyes are moving from word to word.

The primary symptom of exophoria is one eye turning outward when it’s covered or doesn’t have the same visual stimulation as the other eye.

Other symptoms of exophoria may include:

  • headaches
  • sore eyes
  • difficulty reading (especially in children)
  • low reading comprehension
  • dislike of reading
  • issues with concentration
  • double vision
  • difficulty with tasks that are done close in or near the eyes

These symptoms can also be signs of other vision conditions. Many of these types of eye or vision conditions are closely related and have very similar symptoms.

Treatment for exophoria can vary based on the severity of the symptoms. Some of the treatment options for exophoria may include the following:

  • Corrective lenses. These may or may not include the use of prisms.
  • Eye exercises. One such exercise is the pencil pushup.

To perform pencil pushups:

  1. Hold a pencil in front of your face and focus on one of the words on its side.
  2. As you maintain that focus, move the pencil closer to your eyes, aiming for the bridge of your nose.
  3. Continue moving it closer until the word blurs or you start getting double vision.
  4. Repeat this sequence as many times as recommended by your eye doctor.

Surgery is not usually needed or recommended to correct exophoria.

There are several conditions that are similar to, or may include, exophoria.

The following are some of these associated conditions:

  • convergence insufficiency
  • strabismus
  • exotropia
  • eye-tracking
  • eye-teaming

Complications include difficulty with reading and reading comprehension. However, the main complications occur when the condition is not diagnosed.

A child with undiagnosed exophoria may be diagnosed with other conditions including:

  • ADHD
  • learning disabilities
  • short attention span issues
  • dyslexia

Children with undiagnosed exophoria may also be perceived as not trying in school or when reading.

These are just some of the conditions that may be looked at in someone with exophoria. If any of these issues exist, it’s important that you have a qualified eye professional rule out exophoria first.

Once properly diagnosed, exophoria can be treated and corrected. It usually takes several months of regular treatment or exercises to correct exophoria.

Most treatments are done at home, so it’s important that you do your exercises regularly as prescribed by your doctor.

Exophoria has been known to reoccur if your eyes become strained or if you have an illness. In the case of reoccurrence, treatments will again correct the condition.