The Association between Level of Control and Exodeviation after the Monocular Occlusion Test in Pediatric Patients with Intermittent Exotropia

PURPOSE: We investigated the association between the level of control and exodeviation after the monocular occlusion test (MO) in pediatric patients with intermittent exotropia. METHODS: We retrospectively reviewed the records of pediatric patients with intermittent exotropia who visited Yeungnam University Hospital between September 2015 and December 2020. The largest exodeviation obtained before and after 1 hour of MO were compared. The LACTOSE (Look And Cover, then Ten seconds of Observation Scale for Exotropia) control scoring system was used to measure the level of control. Controllability was defined when the patient had the subjective awareness of exotropia and the instinctive ability to correct ocular deviation. RESULTS: Five hundred and three consecutive patients (260 male and 243 female patients; mean age, 7.8 years) were included. In all control scores, exodeviation significantly increased after the MO (p < 0.001). However, the patients with an increase in exodeviation ≥5 prism diopters (PD) after the test did not show any significant association with the control scores. The presence of controllability was significantly associated with an increase of ≥5 PD at near (p = 0.034). CONCLUSIONS: Exodeviation showed significant increase after the MO, regardless of the level of control, in pediatric patients with intermittent exotropia. There was no significant association between the control scores and an increase of ≥5 PD after the MO. Patients with controllability were more likely to show increase in exodeviation after the MO.