Objective To investigate the incidence,height and extent of posterior vitreous detachment (PVD) after laser in situ keratomileusis (LASIK) in young adult myopes.Methods This was a prospective case-series study.Optical coherence tomography (OCT) combined with B-scan was performed to examine the PVD on 305 myopia patients (607 eyes) before LASIK and 1 day,1 month,3 months, and 6 months after surgery.The incidence of PVD was observed before and after the surgery.The eyes with preoperative PVD, which had been confirmed by OCT,were measured after surgery to examine the height and the extent of PVD (the near distance and the far distance to the fovea centralis of the macula) among various quadrants of the perimacular after surgery.Data were analyzed with a x2 test,a one-way ANOVA, and a Friedman rank test.Results The incidence of PVD at 1 day, 1 month, 3 months, and 6 months after surgery was 31.8％, 32.0％, 33.2％,34.7％, respectively.The incidence of various indicators after surgery was significantly higher than that before surgery (26.5％) (x2=10.462,P＜0.05).The heights of PVD in the superior quadrant began to increase 1 month after surgery (F=4.056,P＜0.05).Though the heights of PVD in the other three quadrants were also heightened increased after surgery, there were no statistically significant differences, compared to preoperative level.The near distances of PVD in the superior, inferior,nasal, and temporal quadrants of the perimacular area were decreased after surgery (M=321.0,102.8,113.8,228.5,P＜0.05),while the furthest distances of PVD in the above four quadrants were increased after surgery (M=276.1, 139.8, 157.6,204.7,P＜0.05).The far distance of PVD in the superior and temporal quadrants had a tendency of continuous increases,while the far distance of PVD in the inferior and nasal quadrants and the near distance tended to stabilization during the 6months after surgery.Conclusion In the short term,LASIK may increase the occurrence of PVD,raise the height of PVD and enlarge the extent of PVD in young adult myopes.