In divergence insufficiency, the characteristic finding is an esodeviation that is greater at distance than at near. The deviation is horizontally comitant, and fusional divergence is reduced. There are 2 forms of divergence insufficiency: a primary, isolated form; and a secondary form that is rare and associated with neurologic abnormalities, including pontine tumors, increased intracranial pressure, or severe head trauma. In these secondary cases, the divergence insufficiency is probably due to a mild sixth nerve paresis. Patients with secondary divergence insufficiency require neuroimaging to rule out treatable intracranial lesions.
Primary divergence insufficiency is an increasingly diagnosed type of adult strabismus. More recently termed age-related distance esotropia, the entity is a slowly progressing, benign condition that occurs predominantly in patients older than 50 years. Affected individuals report a gradual onset of horizontal diplopia that is present at distance but not at near. Imaging may demonstrate thinning, elongation, and rupture of the connective tissue between the lateral and superior rectus muscles and sagging and elongation of the lateral rectus muscles. Management consists of base-out prisms, botulinum toxin injection of the medial rectus muscles, and strabismus surgery. In patients with age-related distance esotropia, reestablishment of binocular fusion generally occurs following treatment.
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.