Purpose: To measure the orbital opening angle (OOA) in patients with strabismus via magnetic resonance imaging (MRI) and analyze its association with acquired esotropia.
Subjects and methods: This study involved 142 patients who underwent orbital MRI at an outpatient consultation for strabismus at the department of ophthalmology of Kyoto Prefectural University of Medicine or Baptist Eye Clinic from December 2015 to April 2018. Patients with a history of surgery for strabismus were excluded, and 180 sides of 90 patients［46 males/44 females; mean age: 45.3±23.8 years (range: 7-89 years) ］were analyzed. Patients were categorized into six groups: Group A: highly myopic strabismus (esotropia with dislocation of the globe, 10 cases); Group B: acquired comitant esotropia with myopia (17 cases); Group C: sixth cranial nerve palsy (7 cases); Group D: esotropia other than that in Groups A, B, or C (18 cases); Group E: exotropia (7 cases); and Group F: others (31 cases). We measured the angle between the midline and the deep lateral orbital wall in a horizontal section.
Results: In Groups A, B, C, D, E, and F, the mean OOA was 53.3±4.9° (mean±SD), 46.0±3.8°, 47.6±2.9°, 47.3±4.4°, 48.1±3.7°, and 48.4±3.7°, respectively.
Conclusions: The OOA was significantly larger (p<0.01) in patients with highly myopic strabismus (Group A) than in the patients in the other five groups. The OOA may be associated with the cause of acquired esotropia.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 124: 555-563, 2020.