Purpose: To measure orbital opening angles using magnetic resonance imaging (MRI) and evaluate the utility and reproducibility of measurements.
Patients and methods: Among patients who visited the outpatient clinic of the Department of Ophthalmology of Baptist Eye Clinic or the Department of Ophthalmology, Kyoto Prefectural Medical University Hospital for strabismus between January 2015 and April 2018, 90 patients who underwent imaging of T1-weighted images via orbital MRI and for whom image analyses were possible were included. Orbital opening angles were measured using image analysis software (ImageJ^Ⓡ), and intraclass correlation coefficients (ICC) and Bland-Altman analyses were used as indicators of reproducibility. Reproducibility between and within examiners were also assessed.
Results: The mean orbital opening angle in 180 eyes of all 90 patients measured in this study was 46.9°±4.7°. Inter-examiner ICC was 0.506 in the right and 0.658 in the left, and intra-examiner ICC was 0.784 in the right and 0.823 in the left, with moderate agreement observed when assessments were performed by different examiners. In the Bland-Altman analysis, the variability was also low both between examiners and within examiners, and the orbital opening angle and variability did not show certain tendencies.
Conclusion: The measurement of orbital opening angles using MRI was shown to be highly reproducible, which may be helpful in elucidating the pathophysiology of strabismus in the future.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 124: 479-483, 2020.