Long-term postoperative development of stereopsis in infantile exotropia

Purpose: The purpose of this study was to investigate serial changes in stereopsis in patients with infantile exotropia during follow-up testing. Design: This was a retrospective case series. Methods: Twenty-one patients diagnosed with exotropia before age 1 who underwent surgery and examination for stereopsis at least 3 times after surgery were included in this study. Clinical records of the patients were retrospectively reviewed. Patients with binocular sensory test results exceeding 8 prism diopters (PD) of exodeviation or 5 PD of esodeviation were excluded from the study. The change in binocular status and associated clinical features were assessed in all patients. The patients were followed up for a mean of 54 months. Results: The average ages at the initial and final stereopsis tests were 4.7 years and 7.1 years, respectively. The mean angle of deviation at the final stereopsis test was 1.33 ± 2.48 PD at distant and 0.86 ± 2.24 PD at near. Initial stereopsis ranged from 3000 (including no stereopsis) to 60 arc seconds. Three patients had excellent stereopsis of 60 arc seconds in the initial test. Five of the other 18 patients initially showed gross stereopsis but developed excellent stereopsis of 60 arc seconds by the final test. Conclusions: Even if patients do not show excellent stereopsis of 60 arc seconds in an initial diagnostic test, they should receive regular screenings as they age to assess the development of stereopsis in infantile exotropia.