Postoperative change in lateral rectus muscle insertion measured by anterior segment optical coherence tomography

Abstract

Aims: The aims of this study were to investigate the longitudinal change in lateral rectus (LR) muscle insertion after recession surgery, and to evaluate a relationship between insertion distance and postoperative amount of deviation. Methods: We recruited 31 patients who underwent primary LR recession surgery with normal anterior segment structures. An AS-OCT scan of the LR muscle was performed at every visit. Data on sex, age, degree of deviation (prism diopter), and spur-LR insertion distance using AS-OCT were collected at preoperatively and postoperative months 1, 3, and 6. Spur-LR insertion was defined as the shortest distance between the insertion of the LR muscle and the scleral spur was measured using the caliper function in the AS-OCT software. Results: The mean distance of spur-LR insertion measured with AS-OCT was 5.5±0.7 mm preoperatively, and 11.1±0.9 mm at 1 month, 11.5±0.8 mm at 3 months, and 11.0±0.7 mm at 6 months postoperatively. There were significant differences in spur-LR insertion between postoperative 1 and 3 months, and between 3 and 6 months (generalized estimating equation, all P<0.001). The overall spur-LR insertion measurement has a significantly negative correlation with postoperative amount of deviation (Pearson’s correlation, P=0.035, r=−0.218). Conclusions: AS-OCT is a useful instrument for understanding postoperative changes in EOM after tissue swelling subsides.