What is Exotropia?
Exotropia is an eye misalignment (strabismus) where one eye is turned outward. The turn may be constant or intermittent. The eye turned in may always be the same eye or the condition may be called alternating exotropia when alternate eyes deviate. Exotropia is the most common type of strabismus and accounts for up to 25% of all ocular misalignment in early childhood. Transient intermittent exotropia is sometimes seen in the first 4 – 6 weeks of life and can resolve spontaneously by 6 – 8 weeks of age. Commonly, it may develop intermittently between 1 – 4 years of age, when the child is ill, tired, or focusing on distant objects, but is not present when focusing on near objects.
- Exotropia is an outward turn of an eye.
- Intermittent exotropia is the most common type of strabismus.
- Treatment may include glasses, vision therapy and/or surgery.
The etiology of exotropia is unknown, but those with exotropia have an impaired ability to maintain fusion and alignment. No specific refractive error is associated with exotropia. Patients with exotropia are at a higher risk of developing attention deficit hyperactivity disorder, learning disabilities, short attention span, social inhibitions, and dyslexia. There are several different types of exotropia.
Congenital exotropia is a constant, large angle exotropia that begins during the first 6 months of life and does not resolve on its own. Amblyopia is more common in these patients compared to intermittent exotropia.
Sensory exotropia develops in older children or adults with one eye that does not see well.
Intermittent exotropia is the most common type of exotropia and has a usual onset between infancy and 7 years of age. The intermittent deviation is more likely to be present when the child is fatigued, ill, or in a lowered mental state.
Consecutive exotropia occurs in a patient with a history of esotropia treated with glasses or surgery, and then converts to exotropia.
Risk Factors for Exotropia
Risk factors include neurologic disorders, prematurity, maternal substance and alcohol abuse during pregnancy, genetic abnormalities, uncorrected refractive errors and a family history of strabismus. Although there is no specific racial predilection for exotropia, Asians with strabismus are more often exotropic when compared to other racial groups.
Symptoms of Exotropia
The symptoms of exotropia may be mild or severe, but include:
- Reduction in binocular vision
- Reduction in stereopsis
- Diplopia (double vision)
- Asthenopia (eye strain/fatigue)
- Frequent headaches
All patients with exotropia need a comprehensive eye exam. The doctor will measure visual acuity, assess binocular function and stereopsis, evaluate motility, perform strabismus measurements, measure fusional amplitudes, and complete a cycloplegic refraction. A health assessment of the front and the back of the eye will be performed.
Treatment is primarily refractive correction, binocular visual training therapy and surgery, but their indications are not well-defined or measurable. The goal of surgery is to treat the maximum measured distance angle.