A prospective study of treatments for adult-onset divergence insufficiency–type esotropia

PURPOSE: To describe 10-week and 12-month outcomes following treatment for divergence insufficiency-type esotropia in adults.

METHODS: In this prospective observational study, 110 adults with divergence insufficiency-type esotropia, with a distance esodeviation measuring 2 Δ to 30 Δ and at least 25% larger at distance than near, and binocular diplopia present at least "sometimes" at distance, were enrolled at 28 sites when initiating new treatment. Surgery, prism, or divergence exercises/therapy were chosen at the investigator's discretion. Diplopia was assessed at enrollment and at 10-week and 12-month outcome examinations using a standardized diplopia questionnaire (DQ). Success was defined as DQ responses of "rarely" or "never" when looking straight ahead in the distance, with no alternative treatment initiated.

RESULTS: Of the 110 participants, 32 (29%) were prescribed base-out prism; none had received prior treatment for esotropia. Success criteria were met by 22 of 30 at 10 weeks (73%; 95% CI, 54%-88%) and by 16 of 26 at 12 months (62%; 95% CI, 41%-80%). For the 76 (68%) who underwent strabismus surgery (82% of whom had been previously treated with prism), success criteria were met by 69 of 74 at 10 weeks (93%; 95% CI, 85%-98%) and by 57 of 72 at 12 months (79%; 95% CI, 68%-88%).

CONCLUSIONS: In this study cohort, both base-out prism as initial therapy and strabismus surgery (usually following prism) were successful in treating diplopia for most adults with divergence insufficiency-type esotropia when assessed during the first year of follow-up.