目的: 探讨近视眼准分子激光原位角膜磨镶术(laser in situkeratomileusis，LASIK)对角膜后表面稳定性的影响。 方法:采用Orbscan-Ⅱz及Pentacam眼前节分析仪测量近视眼LASIK手术前、手术后1wk;1,3,6mo的角膜后表面高度，统计分析其术前、术后变化情况。 结果: Orbscan-Ⅱz测量发现LASIK术后角膜后表面向前膨隆（P=0.000），且与术前近视度数、中央角膜厚度呈负相关（r=-0.403,P=0.001; r=-0.349,P=0.004）和切屑深度呈正相关（r=0.411,P=0.001）。Pentacam测量结果显示LASIK术后角膜后表面并未发生前移或后移（P＞0.05）。 结论: LASIK术后角膜后表面并未发生前凸等改变， Orbscan-Ⅱz眼前节分析系统测量结果显示的LASIK术后角膜后表面前凸可能是因为LASIK手术改变了角膜对Orbscan检查设备成像系统的放大效应。

AIM: To check whether myopic laser in situ kerato- mileusis(LASIK) induces changes on the posterior corneal surface. METHODS: Orbscan-Ⅱz and Pentacam were used to measure preoperative and postoperative posterior corneal topography in 66 eyes (of 66 subjects) that had undergone standard myopic LASIK surgery. Changes in the posterior corneal elevation, and anterior chamber depth were compared using the paired sample t test. RESULTS: Measured with Orbscan-Ⅱz, significant forward shifting of the central posterior corneal surface was found after LASIK (P=0.000), while measured with Pentacam, no significant difference in posterior corneal displacement was found (P＞0.05). Preoperative refraction (r=-0.403,P=0.001), central corneal thickness (r=-0.349, P=0.004), ablation depth (r=0.411, P=0.001) were significantly correlated with the posterior corneal displacement measured with Orbscan-Ⅱz. CONCLUSION: No forward shifting of the central posterior corneal surface occurred after LASIK. Orbscan-Ⅱz was affected by the magnification effect of corneas after LASIK, when it was used to measure the posterior corneal surface.