Intermittent exotropia is the most common type of manifest exodeviation.
The onset of intermittent exotropia is usually before age 5 years, and the exotropia typically continues into adulthood. The exodeviation becomes manifest during times of visual inattention, fatigue, stress, or illness. Parents of affected children often report that the exotropia occurs late in the day or when the child is daydreaming or tired. Exposure to bright light often causes exodeviation and a reflex closure of 1 eye (which is why strabismus is sometimes referred to as a “squint”).
Exodeviations are usually larger when the patient views distant targets, and they may be difficult to elicit at near. Because most parental interactions with young children occur at near, parents of a child with intermittent exotropia may not notice it initially. Intermittent exotropia can be associated with small hypertropias, A and V patterns (see Chapter 10), and overelevation and underelevation in adduction (see Chapter 11).
Left untreated, intermittent exotropia may remain stable, resolve, or progress, sometimes to constant exotropia. Because of suppression, children younger than 10 years with intermittent exotropia rarely report diplopia. They retain normal retinal correspondence and good binocular function when orthotropic. Amblyopia may occur if the strabismus is poorly controlled or becomes constant. Adults with poorly controlled intermittent or constant exotropia often experience significant psychological stress, anxiety, and depression because of their strabismus. Adults with strabismus often report reduced quality of life, obtain lower levels of education, and may have limited career choices and advancement opportunities.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.