飞秒激光与常规刀片准分子激光术后角膜后表面高度早期变化的对照研究

背景 飞秒激光准分子激光角膜原位磨镶术（FS-LASIK）已广泛用于屈光不正的矫治,具有良好的安全性和可预测性,但缺乏术后角膜后表面高度动态变化的研究.了解FS-LASIK术后角膜后表面高度的动态变化对于预防医源性角膜膨隆具有重要意义. 目的 分析FS-LASIK术后早期角膜后表面高度的变化情况,并与前弹力层下准分子激光角膜磨镶术（SBK）、上皮刀辅助的准分子激光上皮瓣下角膜磨镶术（Epi-LASIK）术后情况进行比较.方法 采用前瞻性非随机对照研究设计.纳入2010年6-9月在天津市眼科医院行准分子激光角膜屈光手术的近视及近视散光患者72例144眼,分为FS-LASIK组23例46眼,SBK组28例56眼,Epi-LASIK组21例42眼.分别于术前及术后1d（Epi-LASIK组术后3d）、1周、1个月用Visante OMNI测量术眼角膜后表面水平子午线和垂直子午线上角膜顶点及距离角膜顶点1、2、3 mm共13个点的角膜后表面高度,采用重复测量的方差分析进行统计学分析. 结果 在FS-LASIK组,术前、术后1d、1周、1个月术眼角膜顶点方位角膜后表面高度分别为（2.03±0.78）、（2.26±0.96）、（2.16±0.85）和（2.06±0.89）μm；在距角膜顶点1 mm、2 mm区域,术眼的术后变化趋势与角膜顶点区域的变化相同；在距角膜顶点3 mm区域,上述4个时间点术眼的角膜后表面高度分别为（-4.64±1.68）、（-5.39±1.85）、（-4.73±1.71）和（-4.71±1.52） μm.在SBK组,术前及术后1d、1周、1个月角膜顶点区域角膜后表面高度分别为（1.44±0.63）、（1.74±0.75）、（1.66±0.69）和（1.53±0.71） μm；在距角膜顶点1 mm、2 mm区域,术眼术后角膜后表面高度变化趋势与角膜顶点区域一致；在距角膜顶点3 mm区域,上述4个时间点角膜后表面高度分别为（-5.09±1.76）、（-5.48±1.68）、（-5.27±1.81）和（-5.19±1.77）μm,术后发生了轻微后移.在Epi-LASIK组,术前,术后3d、1周、1个月在角膜顶点区角膜后表面高度分别为（2.47±0.73）、（1.55±1.43）、（1.55±1.37）和（2.37±1.06） μm,术后发生轻微后移；而在距角膜顶点1 mm、2 mm区域则与角膜顶点术后变化趋势不同,术后3d角膜后表面高度分别由术前的（1.55±0.51）μm、（-1.87±0.91）μm变为（1.92±0.91） μm、（0.24±1.35） μm,角膜发生轻微前移.在距角膜顶点3 mm区域,角膜后表面高度变化趋势与角膜顶点区相同.FS-LASIK组和SBK组术眼术后角膜后表面高度的变化较小,Epi-LASIK术后1d、1周时较术前变化较大.术后1d时,FS-LASIK相对于SBK变化较大.不同的手术方式及不同时间点角膜后表面高度的差异均无统计学意义（P＞0.05）.结论 FS-LASIK术后早期中央区和旁中央区的角膜后表面高度发生了微小的变化,但随时间的变化逐渐恢复至术前水平,与SBK、Epi-LASIK相比无明显差异.

Comparison of early change of posterior corneal elevation after femtosecond laser flap creation,sub-Bowman keratomileusis,epipolis laser in situ keratomileusis

Background Femtosecond laser flap creation （FS-LASIK） has good safety and predictability in the treatment of refractive error,but few studies have examined the dynamic change of posterior corneal elevation after FS-LASIK.The change of posterior corneal elevation after FS-LASIK is of important significance for the prevention of iatrogenic corneal expand after the surgery.Objective This study was to assess the early change of posterior corneal elevation after FS-LASIK,and compare these changes with FS-LASIK,epipolis laser in situ keratomileusis （Epi-LASIK） and sub-Bowman keratomileusis （SBK） refractive surgeries.Methods In this prospective nonrandomized controlled study,144 eyes of 72 patients were divided into FS-LASIK group （46 eyes of 23 patients）,SBK group （56 eyes of 28 patients） and Epi-LASIK （42 eyes of 21 patients）according to different surgery modes.The posterior corneal elevation was measured using Visante OMNI before operation and 1 day,7 days and 1 month after operation,respectively.The corneal elevation change values of thirteen measuring points across the posterior cornea vertex and 1,2,3 mm away from the vertex of cornea on the horizontal and vertical meridian were obtained and evaluated.The results were analyzed with one-way repeated measures ANOVA by SPSS 13.0 software.Results In the FS-LASIK group,the posterior corneal elevation in the vertex was （2.03 ±0.78）,（2.26 ±0.96）,（2.16 ± 0.85）and （2.06±0.89）μm before operation and 1 day,7 days and 1 month after operation,respectively.In the 1 mm and 2 mm districts away from the vertex,a similar change trend in the posterior corneal elevation was seen to that of the vertex,and the 3 mm district away from vertex,the posterior corneal elevation value was （-4.64 ± 1.68）,（-5.39 ± 1.85）,（-4.73 ± 1.71） and （-4.71 ± 1.52） μm at the four different time points.In the SBK group,the posterior corneal elevation of the vertex was （1.44 ± 0.63）,（1.74 ± 0.75）,（1.66 ± 0.69） and （1.53 ± 0.71） μm before operation and 1 day,7 days and 1 month after operation.In the 1 mm and 2 mm districts,the trend was the same with the vertex postoperatively,and in the 3 mm district away from vertex,the measuring value was （-5.09 ± 1.76）,（-5.48±1.68）,（-5.27±1.81） and （-5.19±1.77） μm at various time points,showing a tiny backward displacement.In the Epi-LASIK group,the posterior corneal elevation of the vertex was （2.47 ± 0.73）,（1.55 ±1.43）,（1.55±1.37） and （2.37±1.06）μm before operation and 1 day,7 days and 1 month after operation,with a tiny backward displacement; in the 1 mm and 2 mm districts away from the vertex,the change trend of corneal elevation was different from the vertex area.The posterior corneal elevation altered from preoperative （1.55 ±0.51）μm and （-1.87±0.91） μm to postoperative （1.92 ±0.91） μm and （0.24 ± 1.35） μm respectively.In the 3 mm district away from the vertex,the change was similar to vertex in postoperation.Smaller change was seen in postoperation in the FS-LASIK group and SBK group compared with the Epi-LASIK group,and posterior corneal elevation showed a bigger change in the FS-LASIK group than SBK group 1 day after operation.No statistically significant difference was found in posterior corneal elevation among the three surgery modes and various time points （all at P＞0.05）.Conclusions The posterior corneal elevation of both central and paracentral area appears tiny change in the early stage and then returns to preoperative level with time after FS-LASIK.FS-LASIK is a safe surgical technique like SBK and Epi-LASIK.