两种飞秒激光制作准分子激光原位角膜磨镶术角膜瓣形态学和角膜生物力学指标的比较

目的评估并比较IntraLase飞秒激光和ZiemerLDV飞秒激光制作的准分子激光原位角膜磨镶术（LASIK）角膜瓣的均匀性、可预测性、精确性和重复性以及术后角膜生物力学各指标的变化。方法前瞻性、平行对照研究。对接受飞秒激光制瓣的LASIK手术患者30例（60眼）进行随访，14例使用IntraLase飞秒激光制作角膜瓣．16例使用ZiemerLDV飞秒激光制作角膜瓣，2组预期制得的角膜瓣厚度均为110μm。术前及术后1周、1个月、3个月使用Visante眼前节光学相干断层扫描（OCT）测量中央角膜厚度．并对制得的角膜瓣水平及垂直方向各7个点（角膜顶点以及距离顶点鼻、颞侧和上、下方各为1．0、2．0、3．0mm处）的厚度进行测量。对2组术前及术后1个月、3个月应用眼反应分析仪测量角膜阻力因子（CRF）和角膜滞后量（CH）的变化。数据采用重复测量方差分析和独立样本t检验。结果术后1周、1个月、3个月IntraLase组制得角膜瓣角膜顶点处平均角膜瓣厚度分别为（125±11）Ixm、（125±10）μm和（126±7）Ixm．各时间点2个方向上不同测量点间的角膜瓣厚度差异有统计学意义（F=11．85、12．638、8．78、8．18、4．81、5．39，P〈0．01）。ZiemerLDV组分别为（106±6）μm、（109±7）μm、（109±5）μm，各时间点两个方向上不同测量点间的角膜瓣厚度差异有统计学意义（F=28．20、9．43、18．00、7．14、5．65、4．92，P〈O．01）。术后1周、1个月、3个月IntraLase组制得角膜瓣各测量点的厚度与预期制得的角膜瓣厚度的差值平均值分别为（20．9±3．8）μm、（19．0±3．0）μm、（18．7±3．3）txm，ZiemerLDV组分别为（2．1±3．7）μm、（2．5±3．2）μm、（1．7±2．4）μm，2组各时间点角膜瓣测量点的厚度与预期厚度的差值比较，差异均有统计学意义（P〈0．01）。IntraLase组制得的角膜瓣各测量点的厚度与预期制得的角膜瓣厚度的差值标准差在7～15μm之间，ZiemerLDV组在4～8μm之间。术后1个月、3个月IntraLase组CRF值分别为（7．26±1．45）mmHg、（7．12±1．18）mmHg，CH值分别为（8．53±1．07）mmHg、（8．48±1．02）mmHg，ZiemerLDV组CRF值分别为（6．61±0．65）mmHg、（6．59±0．71）mmhg，CH值分别为（7．99±0．90）mmHg、（7．88±0．86）mmHg，均较术前显著降低，差异有统计学意义（P〈0．01），但2组间差异无统计学意义（P〉0．05）。结论ZiemerLDV制瓣较IntraLase在可预测性、精确性和重复性方面更有优势。2种飞秒激光制瓣的LASIK术后角膜生物力学各参数均较术前显著降低．但两者间无差异。

Corneal flap morphological analysis and corneal biomechanical comparison in laser in situ keratomileusis with two femtosecond lasers

Objective To assess and compare the morphology of laser in situ keratomileusis （LASIK） flaps created by the IntraLase femtosecond laser and the Ziemer LDV femtosecond laser and to assess the effects on corneal biomechanics. Methods This was a prospective and parallel control test. Sixty eyes of thirty patients were treated with LASIK： fourteen patients underwent IntraLase femtosecond laser surgery, while sixteen patients underwent Ziemer LDV femtosecond laser surgery. The corneal flap was set at 110 μm. Flap thickness was assessed at 14 measuring points across each flap at 1 week, 1 month and 3 months postoperatively with a Visante optical coherence tomography （OCT）. The corneal resistance factor （CRF） and corneal hysteresis （CH） were examined before surgery and 1 month and 3 months after surgery with an ocular response analyzer. Data were analyzed using repeated measured ANOVA and independent t test. Results The respective mean corneal flap thicknesses at the top 1 week, 1 month and 3 months postoperatively were 125±11μm, 125~10 μm, 126±7 Ixm in the IntraLase group and were 106±6 μm, 109±7μm, 109±5 μm in the Ziemer LDV group. The mean deviations between achieved and attempted flap thickness were 20.9±3.8 μm, 19.0±3.0 μm, 18.7±3.3 μm in the IntraLase group and were 2.1±3.7μm, 2.5±3.2 μm, 1.7-＋2.4 μm in the Ziemer LDV group. The differences were statistically significant （P〈0.01）. The standard deviation between achieved and attempted flap thickness was 7-15 Ixm in the IntraLase group and was 4~8 Ixm in the Ziemer LDV group. The CRF and CH significantly decreased after surgery in both groups but there were no statistical differences between them. Conclusion The predictability, accuracy and reproducibility were better with the Ziemer LDV femtosecond laser than Intralase femtosecond laser. There were no statistical differences in the corneal biomechanical effects between the two instruments.