LASIK后角膜后表面形态的研究

目的：研究激光角膜原位磨镶术（LASIK）前后，角膜后表面屈光度及曲率半径的改变以及影响因素。方法：随机选择停戴隐形眼镜一月以上的中高度近视41眼进行LASIK治疗，依角膜光学区直径的不同，分3mm区及5mm区两组，应用Orbscan分别观察分析其术前及术后3天、3月角膜后表达屈光度和曲率半径。结果：各组术前与术后各期相比，角膜后表面屈光度和曲率半径的改变均有显著性意义（P＜0.05)，角膜中央变化较周边明显（P＜0.05），角膜3mm区术后3月与3天相比差异有显著性意义（P＜0.05)，角膜后表面曲率半径的改变与患眼正常眼压无关，与 术后角膜厚度存在统计学相关性（r=-0.6,P＜0.05)，厚度小于350μm时角膜后表面形态变化较厚度大于350μm时明显（P＜0.01)。结论：激光角膜原位磨镶术可引起角膜后表面屈光度增大，曲率半径减少，术后角膜厚度是主要影响因素，将术后角膜厚度大于350μm作为安全指标仍需作进一步的研究。

The study on the posterior corneal surface topography after LASIK

Objective：To investigate the changes in the posterior corneal surface topography after LASIK and the factors that influence the results.Methods：This study comprised 41 eyes of middle and high myopia(2 patients) that had undergone LASIK. Diopter and radius of curvature of posterior corneal surface were measured by Orbscan before operation, and at 3rd day, 3rd month post-operatiion. Eyes were divided into two groups(3mm area and 5mm area) according to the optical diameter of cornea.Results：Significant difference in posterior corneal surface topography existed between pre-operation and post-operation(P<0.05) in corneal center and peripheral(P<0.05). There is significant difference in 3 months and 3 days post operation in 3mm area(P<0.05). The change in radius of curvature of posterior corneal surface was correlated with corneal thickness after LASIK(r=-0.6,P<0.05), but irrelevant to IOP. The change of posterior corneal surface topography was more significant in the corneal thickness less than 350μm(P<0.01).Conclusion：LASIK can decrease the radius of curvature of the posterior corneal surface. The corneal thickness after LASIK is a major contributing factor.