Adult-onset chronic divergence insufficiency esotropia: Clinical features and response to surgery

Purpose To analyze the clinical and demographic features and surgical outcomes of a series of patients with adult-onset chronic divergence insufficiency esotropia to investigate novel associations of this condition with race, sex, and surgical dose-response. Methods The medical records from a single practice were retrospectively reviewed to identify patients with adult-onset chronic divergence insufficiency esotropia who underwent strabismus surgery over a 12-year period. Demographic, clinical, surgical, and outcome data were analyzed to determine statistically significant findings with respect to race, sex, and surgical results. Results A total of 27 patients (all white; 23 females) were identified. The average age was 72 years. All patients underwent medial rectus recession bilaterally or unilaterally. The dose-response to surgery (1.6^Δ/mm) was significantly less than that predicted by standard surgical nomograms; however the individual dose-responses varied directly with preoperative angle. Conclusions Adult-onset chronic divergence insufficiency esotropia occurs predominantly in white women in our experience. Medial rectus recession is an effective surgical treatment when augmented recession amounts are employed. The findings that surgical dose-response was relatively low but increased with preoperative angle suggest a mixed mechanism of chronic lateral rectus weakness combined with reduced medial rectus elasticity.