Influencing factors for eye cyclotorsion and pupil centroid shift during LASIK

Objective To investigate the influencing factors for eye cyclotorsion and pupil centroid shift during LASIK.Design Non-controlled retrospective case series.Participant 131 patients (262 eyes) with myopia received bilateral LASIK.Methods Eye cy- clotorsion and pupil centroid shift were measured with Custom Vue~(TM) software during operation and compared with age,gender,right or left eye,flap-making method,spherical equivalent (SE),pupil diameter before and during operation.Main Outcome Measures The de- gree of eye cyclotorsion and distance of pupil centroid shift during LASIK.Results The mean eye cyclotorsion during LASIK was 3.07°±2.07°(0°-8.6°).The mean pupil centroid shift was 0.33±0.14 mm (0.04-0.51 mm).The eye cyclotorsion was relevant to preoperative pupil size,difference of pupil size before and during operation,and preoperative SE (r=0.188,0.156,0.130,all P0.05).Eye cyclotor- sion of subjects with preoperative pupil diameter7.0 mm was higher than that of with pupil diameter≤7.0mm (3.35°±2.17°,2.71°±1.89°,P=-0.014).Pupil centroid shift was higher in fight eyes than that in left eyes (0.39±0.12 mm,0.28±0.13 mm,P=0.000).Conclu- sion Eye cyclotorsion and pupil centroid shift during LASIK can be measured with Custom Vue~(TM) system.The eye cyclotorsion may be influenced by the preoperative pupil size.The pupil centroid during LASIK was more significant in the right eyes than in the left eyes.