To analyze and characterize the medial and lateral rectus muscles in patients with exotropia using anterior segment optical coherence tomography (AS-OCT). This study included 24 patients with exotropia (48 eyes) and 25 healthy individuals (50 eyes). Anterior segment optical coherence tomography was used to construct the en face images. The anterior chamber angle to the extraocular muscle insertion distance, muscle width, and muscle fiber angle from the muscle insertion sites were compared between the exotropia and the control groups. The correlation between these parameters and age or angle of deviation was evaluated. The mean ages were 13.2±4.1 years for the exotropia group and 17.6±7.2 years for the control group. The lateral rectus angle was significantly more inwardly rotated in the exotropia group than in the control group (1.6±6.3°, −1.4±4.0°, p=0.014). With increasing angle of deviation, the width of the lateral rectus increased (p=0.002). Our results indicate that the lateral rectus angle is significantly more inwardly rotated in patients with exotropia. These findings should contribute to a deeper understanding of the extraocular muscles in patients with this condition.