Clinical Features According to the Type of Intermittent Exotropia: Korean Intermittent Exotropia Multicenter Study

Abstract

Background/Objectives: To determine the clinical features of different types of intermittent exotropia according to the distance and near angles of exodeviation. Methods: This study included 5331 patients with intermittent exotropia. The patients were divided into three groups according to the near-distance differences in their exodeviations: (1) Basic-type: difference between distant and near angles of the exodeviation < 10 prism diopters (PD); (2) Convergence insufficiency (CI)-type: near-distance angle >= 10 PD; (3) Divergence excess (DE)-type: distance-near angle >= 10 PD. The main outcome measures were demographics, clinical characteristics of exotropia, subjective symptoms, medical history, and family history. Results: Overall, 4599 (86.2%) patients had basic-type exotropia, 500 (9.4%) had CI-type, and 232 (4.4%) had DE-type exotropia. Older age and greater magnitude of myopia were associated with CI-type exotropia. A-pattern exotropia, superior oblique (SO) overaction, good fusional control, good stereoacuity, and diplopia were most common in CI-type exotropia. SO underaction and photophobia were most frequently observed in DE-type exotropia compared to the other types. Conclusions: The clinical characteristics varied among the different types of intermittent exotropia. CI-type exotropia was most frequently associated with older age and greater myopia. DE-type exotropia was associated with frequent photophobia.