Exotropia (divergent strabismus) is less common than esotropia. As it is usually acquired, the disorder is encountered more often in adults than in children, who more frequently exhibit esotropia. Exotropia less frequently leads to amblyopia because the strabismus is often alternating. Occasionally what is known as "panorama vision" will occur, in which case the patient has an expanded binocular field of vision. The following forms are distinguished:
❖ Intermittent exotropia. This is the most common form of divergent strabismus. In intermittent exotropia, an angle of deviation is present only when the patient gazes into the distance; the patient has normal binocular vision in near fixation (Figs. 17.6a and b). The image from the deviating eye is suppressed in the deviation phase. This form of strabismus can occur as a latent disorder in mild cases, meaning that the intermittent exotropia only becomes manifest under certain conditions, such as fatigue.
❖ Secondary exotropia occurs with reduced visual acuity in one eye resulting from disease or trauma.
❖ Consecutive exotropia occurs after esotropia surgery. Often the disorder is overcorrected.
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