Sensory strabismus--eso or exo?

The type of horizontal strabismus from loss or impairment of vision is thought to depend on patient age at the time of vision loss. Association between the age at onset of vision loss and development of esotropia vs exotropia will be determined.

Patients with a diagnosis of sensory strabismus and visual acuity of 20/40 or poorer were reviewed as well as patients with diagnoses consistent with the development of sensory strabismus. Parameters considered were age at onset of vision loss and type of strabismus. Patients were excluded if the age at onset was not clear.

Of 123 patients with sensory strabismus reviewed: 82 (67%) had unilateral vision loss; 41 (33%) had bilateral vision loss; 75 (61%) had congenital vision loss; 50 (67%) developed esotropia; 25 (33%) developed exotropia; 48 (39%) had acquired vision loss; 5 (10%) developed esotropia; and 43 (90%) developed exotropia. A significant difference was noted between age at onset and type of horizontal strabismus (X2= 37.44; P <.0001).

Of patients with congenital vision loss, 67% developed sensory esotropia and 33% developed sensory exotropia. Of those with acquired vision loss, 10% developed sensory esotropia and 90% developed sensory exotropia. Patients with congenital vision loss are significantly more likely to develop esotropia, P <.005, and those with acquired vision loss are significantly more likely to develop exotropia, P <.001.