 The aim of this study is 1 to evaluate the reliability and accuracy of AS-OCT in the measurement of the lateral rectus LR insertion distance, 2to investigate the longitudinal change of LR muscle insertion after strabismus surgery, and 3to determine the effect of insertion movement on the angle of deviation after strabismus surgery. An AS-OCT scan of the LR muscle was performed every visits. Preoperative limbus-LR insertion distance was compared with intraoperative surgical caliper measurement of LR insertion using intraclass correlation coefficient analysis ICC. Data on gender, age, degree of deviation prism diopter, and spur-LR insertion distance using AS-OCT were collected at postoperative months 1,3 6. 