Objective To investigate the difference in visual quality between oval and round corneal flaps in femtosecond excimer laser in situ keratomileusis(FS-LASIK).Methods In a prospective randomized controlled clinical study,patients who voluntarily underwent FS-LASIK surgery in Wuhan University Affiliated Aier Ophthalmology Hospital from June 2022 to February 2023 were randomly divided into oval valve group and round valve group,with 36 patients(72 eyes)in each group.During FS-LASIK,oval and round corneal flaps were made,and excimer laser surgery was performed in parallel.Observe intraoperative and postoperative complications.The unaided visual acuity(UCVA)and spherical equivalent(SE)at 1 day,1 week,1 month and 3 months after surgery were compared between the two groups at 3 months after surgery,and the modulation transfer function(MTF),Strel ratio(SR)and total higher-order aberration at 3 months after surgery were compared between the two groups.Results All patients had successfully completed the surgery without serious complications.There was no significant difference between the oval valve group and the round valve group in UCVA at 1 day,1 week after surgery,1 month after surgery,3 months after surgery.There was no significant difference between the two groups on the postoperative SE at 1 day,1 week after surgery,1 month after surgery,and 3 months after surgery.There was no significant difference in MTF,SR and total higher-order aberration between the two groups at 3 months after surgery.Conclusion Ideal visual acuity can be achieved with either oval or round corneal flap during FS-LASIK,and there is no significant difference in visual quality between the two in the early postoperativeperiod.