Abstract: Objective To observe the changes of posterior corneal surface after transepithelial photorefractive keratectomy (T-PRK) and epipolis laser in situ keratomileusis (Epi-LASIK) for myopia. Design Prospective comparetive case series. Participants 134 eyes of 68 miopia patients were divided into T-PRK group (81 eyes) and Epi-LASIK group (53 eyes). Methods Posterior corneal elevation and Q-value were analyzed using pentacam before and 1 week, 1, 3 and 6 months after operation，respectively. Main Outcome Measures Posterior coneal elevation and Q-value. Results In the T-PRK group, at 1st and 6th month after surgery and in the Epi-LASIK group at 6th month after surgery, the posterior corneal elevation have a statistically significant backward displacement（all P＜0.05）. No statistically significant difference was found in the postoperative corneal Q-value in both groups before and after surgery（all P＞0.05）. There was also no statistically significant difference of postoperative corneal surface elevation and Q-value between the two groups （all P＞0.05）. Conclusion The posterior corneal elevation showing a backward displacement after T-PRK for myopia，while posterior corneal asphericity has no changed.

Key words: myopia, corneal refractive surgery, posterior corneal surface, Q-value