Accuracy of anterior segment optical coherence tomography for pre-operative localization of insertions of extraocular recti muscles

Abstract

Introduction: To study the accuracy of anterior segment optical coherence tomography (AS-OCT) function of Cirrus HD-OCT 500 (Carl Zeiss Meditec, Dublin, CA) in calculating the insertion of rectus muscles from the limbus in patients undergoing primary squint surgery. Methodology: A prospective, double-masked, observational study was conducted on 128 muscles of 46 patients with strabismus who were planned for strabismus surgery between January 2019 and December 2019. Insertion distance from limbus was measured using AS-OCT function of Cirrus HD-OCT 500 preoperatively. Intraoperative measurements were taken using Castroviejo caliper. A Bland-Altman analysis was performed to determine the agreement between the readings. Results: A total of 128 muscles were successfully imaged and evaluated, including 13 superior recti (10.15%), 23 inferior recti (17.96%), 35 medial recti (27.34%) and 57 lateral recti (44.53%). 124 muscles (96.9%) were within 1mm difference, which was considered clinically acceptable. Bland-Altman plots showed the level of agreement between the two methods was good. Conclusion: Anterior segment scan function of Cirrus HD-OCT 500 is an accurate method to detect the insertion of extraocular recti muscles in patients of primary strabismus surgery.