三种准分子激光手术中角膜切削厚度的对比研究

Comparison of corneal ablation depth among three different types of laser corneal refractive surgery

目的通过术中利用光学相干厚度测量的方法评估飞秒激光制瓣联合LASIK、LASIK与LASEK三种手术中角膜切削深度的差异。设计前瞻性比较性病例系列。研究对象2013年3月到2014年5月行阿玛仕准分子激光矫正手术的患者103例200眼,其中飞秒激光制瓣LASIK组50例100眼,角膜板层刀LASIK组30例57眼,LASEK组23例43眼。方法术中使用实时角膜厚度测量(OCP)技术分别测量制瓣后激光切削前和激光切削后的中央角膜厚度,从而计算实际角膜基质切削深度。比较各组实际角膜切削深度与激光系统预期最大切削深度的差异及三种术式实际角膜切削深度与理论切削深度差值的组间差异。主要指标理论角膜切削深度、实际角膜切削深度。结果飞秒激光制瓣LASIK组OCP所测角膜切削深度(117.22±31.13)μm,准分子激光系统预计角膜切削深度(99.52±25.47)μm(t=-12.55,P<0.001)。角膜板层刀制瓣LASIK组OCP所测角膜切削深度(116.30±22.93)μm,预计角膜切削深度(94.26±16.37)μm(t=-12.44,P<0.001)。LASEK组OCP所测角膜切削深度(106.72±23.77)μm,预计角膜切削深度(99.31±20.46)μm(t=-4.44,P<0.001)。实际角膜切削深度与预计值比较,飞秒激光制瓣LASIK组为(17.69±14.10)μm,角膜板层刀制瓣LASIK组为(22.04±13.38)μm,LASEK组为(7.41±10.95)μm。飞秒激光制瓣及板层刀制瓣LASIK组实际角膜切削深度与理论切削深度差值较LASEK术式组切削深度差值较大(P均<0.001)。飞秒激光组与角膜板层刀组之间差异无统计学意义(P=0.15)。结论术中实时光学相干厚度测量的方法所测三种准分子激光手术实际角膜切削深度较激光系统预计值大,术前预测角膜基质床厚度时需考虑到预计值与实际值差值存在。

Objective To compare the corneal ablation depth among three different types of laser surgery by online corneal pachymetry. Design Prospective comparative case series. Participants 200 eyes of 100 moderate and high myopia patients accepted laser surgery, including FEMTO-LASIK group 100 eyes of 50 patients, LASIK group 57 eyes of 30 patients and LASEK 43 eyes of 23 patients. Methods The corneal thickness was assessed intraoperatively with online optical coherence pachymetry （OCP） before and after laser ablation during surgery, and then the actual corneal ablation depth was calculated. The values of actual and theoretical ablation depth, and the difference in the three groups were compared. Main Outcome Measures Theoretical corneal ablation depth, actual corneal ablation depth. Results In FEMTO-LASIK group, the actual corneal ablation depth and theoretical ablation depth werel17.22± 31.13 μm and 99.52±25.47 μm respectively, t=-12.55, P〈0.001; In LASIK group, the actual corneal ablation depth and theoretical ablation depth were 116.30±22.93 μm and 94.26±16.37 μm respectively, t=-12.44, P〈0.001; In LASEK group, the actual corneal ablation depth and theoretical ablation depth were 106.72±23.77 μm and 99.31 -＋20.46 μm respectively, t=-4.44, P〈0.001. The difference between the actual corneal ablation depth and theoretical ablation depth were 17.69-＋14.10 μm in FEMTO-LASIK group, 22.04±13.38 μm in LASIK group and 7.41±10.95 μm in LASEK group. There were no difference between FEMTO-LASIK group and LASIK group, P=0.15, while the difference in LASIK and FEMTO-LASIK were significantly more than that of LASEK group, P〈0.001. Conclusions The actual corneal ablation depth is more than theoretical ablation measured by online OCP during three different types of laser surgery. The difference between the actual corneal ablation depth and theoretical ablation depth should be taken into consideration while calculating the corneal stroma thickness preoperatively.