飞秒激光LASIK手术前后角膜后表面高度变化的研究

目的应用Pentaeam探讨VisuMax飞秒激光准分子激光原位角膜磨镶术（LASIK）矫正高度近视术后角膜后表面高阶像差的变化规律。方法前瞻性连续病例研究。选择行LASIK矫正近视（球镜度数从-0．45D到-8．25D，柱镜度数从0．00D到-3．50D）患者30例（36只眼），使用VisuMax飞秒激光制瓣，采用Pentacam—HR三维眼前节分析诊断系统（Oeulus，Wetzlar，Germany），分别在术前、术后1d、1周、1个月及3个月对术眼进行眼前节三维图像采集，分别测量角膜中央及2、4、6mm直径范围内45°-225°及135°～315°两条子午线上不同点角膜后表面高度值。采用方差分析进行统计分析。结果从统计结果可以看出，在角膜的不同取值部位，术前与术后1d、1周、1个月、3个月相比均无明显统计学差异（P〉0．05）。术后45°～225°子午线上各点角膜后表面高度在1d到1周之间前凸趋势较明显，1个月时已经开始恢复，术后135°～315°子午线上各点以中央及315°半子午线上2mm区域点为分界点分别表现相反的变化趋势，角膜后表面高度在1d到1个月之间变化趋势较小，从术后1个月到术后3个月表现了明显的变化趋势，虽然变化方向相同，但变化的幅度较大。结论飞秒激光LASIK术后角膜后表面高度并未发生明显的变化，提高了手术的安全性，并且随时间区域不同的角膜后表面形态变化规律也揭示了更为复杂的角膜愈合机制，有待进一步的探索。

Analysis on the shape of posterior corneal surface in different corneal regions after laser in situ keratomileusis with femtosecond laser

Objective To observe and evaluate the influence of FS-LASIK on the shape of posterior corneal sur- face by using Pentacam. Methods Thirty-six eyes were evaluated by using Pentacam-HR pre-and post LASIK with Vi- suMax femtosecond laser. The posterior corneal elevation was measured with Scheimpflug imaging （ Pentacam, Oculus ） be- fore FS-LASIK and at lday, 1 week, 1 and 3 months after the surgeries along the 4 optical zones （ center, 2 - ram, 4 - mm, and 6 -mm diameters） at the meridians of 45°-225°and 135°-315°. Results Compared with the values before FS-LASIK, there was no significant shift postoperatively at almost all regions （ P 〉 0.05）. The posterior corneal elevation exhibited a slight forward displacement at 45° -225° meridian from 1day to 1 month postoperatively, returned to original levels from 1 month after FS-LASIK. At 135°-315°meridian, the posterior surface showed as region-dependent changes that could be divided into superior and inferior parts, which displayed backward and forward shift trends, respectively. Conclusion LASIK with the femtosecond laser（VisuMax） can effectively corrected myopia and astigmatism, it also showed extremely safeties. However, more experimental data should be studied to provide better explanations to the changes in corneal shape as a response to FS-LASIK procedures.