中文摘要：

背景飞秒激光技术在角膜屈光手术中的应用已日渐成熟，其术后角膜基质床表面的形态特点值得关注。目的观察并分析飞秒激光光爆破作用对角膜基质表面的影响及特点，探究不同能量的激光脉冲在飞秒激光制作角膜瓣中对角膜基质床表面显微结构的影响，并与机械性角膜板层刀手术后角膜基质床结构进行比较。方法分别采用125、155、195nJ脉冲能量的VisuMax飞秒激光和Moria—M2角膜板层刀对16只新鲜猪眼球进行光爆破及角膜瓣的制作，每组4只眼。术后用S-3400N型扫描电子显微镜观察术后角膜基质床表面的显微结构特点，对飞秒激光和Moria—M2角膜板层刀制瓣后角膜基质床表面的结构进行对比分析。结果飞秒激光制作角膜瓣后发生光爆破作用处的角膜组织被汽化，产生光滑的表面，气泡之间可见残留的组织间桥。125nJ脉冲能量飞秒激光制瓣组表面光滑，可见散在的组织间桥。155nJ脉冲能量飞秒激光制瓣组角膜表面光滑，无组织间桥和机械性损伤。195nJ脉冲能量飞秒激光制瓣组角膜表面可见大量组织间桥和机械性划痕，并可见较大气泡引起的圆形和椭圆形凹痕。飞秒激光制作角膜瓣后的侧切部位组织排列规则，边缘清晰、锐利，周围组织接近正常；机械性角膜板层刀制瓣组角膜基质床表面可见大量翘起的纤维组织，表面组织卷曲，排列不规则，侧切边缘呈钝角，并有纵行划痕。结论与机械性角膜板层刀制瓣法比较，飞秒激光制作角膜瓣后角膜基质床表面的结构更规则，角膜表面更光滑，飞秒激光制瓣法选择155nJ的脉冲能量最为适宜。

英文摘要：

Background The application of femtosecond laser in the corneal refractive surgery has made great progression recent years, but the morphology characteristic of corneal stroma surface after making-flap of femtoseeond laser is closely concerned. Objective This study was to analyze the influence of photodisruption of femtosecond laser on the corneal stroma surface and to investigate the effect of different laser pulse energy on the surface uhrastructure of corneal stroma. Methods Corneal flaps were made with Visu Max femtosecond laser in 16 fresh porcine eyes with the pulse energy 125 nJ, 155 nJ and 195 nJ respectively, and Moria-M2 microkeratome was used as control. Scanning electron microscopy （ S-3400N Hitachi High-Technologies Corp） was used to observe and compare the ultrastruetural characteristic of corneal stroma bed surface after making of corneal flap. Results The corneal stroma was evaporated and created a smooth surface when photodisruption happened in the femtoseeond laser group. Residual tissue bridges could been exhibited among the cavitation bubbles under the scanning electron microscope. Corneal stroma surface was smooth in the 125 nJ pulse energy group, but some tissue bridges still were visible. In the 155 nJ pulse energy group,much more smooth surface was seen without tissue bridges and mechanical damages on the corneal surface. However, the surface quality was worse and many tissue bridges and grooves existed in the 195 nJ pulse energy group. In addition,different sizes of slots caused by big cavitation bubbles were visible with the round and oval shape. The edges were regular and sharp with small damage zone after cutting with femtosecnnd laser. However, many elevated fibril tissues could be seen on the corneal surface after making of flap with microkeratome. Many crimp and irregularity tissues were found on the surface. Blunt surface and indentations appeared in the cutting edge. Conclusions The microslructure of corneal stroma surface is more smoother after making of corneal flap with femt