All About Strabismus
by Dr. Jeffrey Cooper & Rachel Cooper (no relation). © 2001-2008

Exotropia

Exotropia

Exotropia is the outward deviation (turn) of an eye. The deviation may occur while fixating (looking at) distance objects, near objects or both. Fortunately, most exotropia is intermittent (see pictures below -- straight and deviated) and this means that the eye deviation or turn occurs only some of the time. As long as the eyes are straight some of the time, the brain will develop some normal functioning of the eyes (stereoscopic depth perception). Since the brain and eyes work properly some of the time, time is on your side.

Treatment for intermittent exotropia does not have to occur immediately. As a matter of fact, early surgery has the potential of disturbing the ability of the brain for fusion in the future and can cause a permanent reduction in vision (amblyopia).

When the turn occurs during distance viewing the major problem is cosmetic. The child might be accused of daydreaming or not paying attention. The parents will often notice the turn then bring their child to the eye doctor who won't find it. This is because the turn usually occurs during times of inattention, fatigue, or distance viewing not during the anxiety-provoking eye examination. These children often close their eye in bright sunlight.

Treatment consists of vision therapy, patching, glasses and/or surgery. The most successful form of treatment is vision therapy. Therapy should be directed at the cause. In a comparative study using both Optometric and Ophthalmological journals, vision therapy had an overall success rate of 78% as compared to surgery of 48%. Thus, surgery should be reserved only for the large angle intermittent exotropes or when vision therapy is not as successful as expected.

Published success rates are higher for vision therapy than surgery. Many surgeons do not advocate vision therapy either because they are surgeons and thus like to operate and/or they do not have the facilities to perform vision therapy, and/or have not read the medical literature on vision therapy and unaware of its proven success rates in the treatment of exotropia.

A Parent's Choice re: Treatment for Intermittent Exotropia
Read what one parent wrote regarding making the choice between surgery or vision therapy for intermittent exotropia.

Exotropia -- straight

Exotropia -- deviated

When the turn occurs primarily at near (convergence insufficiency) the principal symptoms include diplopia, headaches, loss of concentration while reading, carsickness, avoidance of reading, blurred vision, and/or eyestrain. This is the most common type of type of muscle problem occurring in approximately 5% of the population. Symptoms are on the rise with increase reading and computer use.

The best treatment for convergence insufficiency with or without strabismus is vision therapy which re-establishes the reflexes of convergence. Treatment usually consists of both in office and home exercises. Recent home computerized therapy programs have become effective in eliminating the symptoms associated with convergence insufficiency. This mode of treatment is very successful.

Prismatic glasses can be prescribed to decrease some of the symptoms. Though prisms are effective they are not as effective as vision therapy and may result in adaptation problems so that more prism is necessary in the future to alleviate symptoms. Every Optometric and Ophthalmological textbook agrees that the primary treatment of convergence insufficiency should be vision therapy.

Vision therapy should be the first source of treatment unless the eye turn is very large. In the case that surgery should be performed, it should be followed up with vision therapy. Remember, surgery may lessen the work load but it does not reinforce the eyes working together. Many surgical patients have their strabismus come back in the future. Many surgical patients have multiple surgeries without lasting positive results.