方法：对2013-01/06在我院行LASIK手术的63例120眼患者分别用EX500和A型超声测厚仪进行CCT测量，按A超测量值>550μm，500～550μm，<500μm分为三组。用Moria公司SBK微型角膜刀切开角膜瓣后再次分别用EX500和A超进行CCT测量。EX500进行准分子激光消融，完成后测量剩余角膜基质床厚度。对以上数据进行配对t检验。

结果：术前CCT的平均测量值：A超为527.9±34.3μm，EX500为528.5±34.6μm，两者差异无统计学意义(t=1.736，P=0.085)。其中CCT>550μm组的平均测量值：A超为571.4±17.3μm，EX500为572.7±15.7μm，两者差异无统计学意义(t=1.857，P=0.072)。CCT 500～550μm组的平均测量值：A超为523.4±13.1μm，EX500为524.2±12.4μm，两者差异无统计学意义(t=1.934，P=0.058)。CCT<500μm组的平均测量值：A超为484.5±9.8μm，EX500为483.7±8.9μm，两者差异无统计学意义(t=1.395，P=0.174)。掀起角膜瓣后CCT的平均测量值：A超为401.3±34.2μm，EX500为393.4±38.9μm，两者差异有统计学意义(t=6.669，P=0.000)，EX500测量平均值明显低于A超组。准分子激光消融完成后测量剩余角膜基质床厚度的平均测量值：A超为332.6±38.3μm，EX500为307.3±37.1μm，两者差异有统计学意义(t=17.165，P=0.000)。

结论：对于LASIK患者术前角膜CCT的测量，EX500与A超的平均测量值无明显差异，但对于掀起角膜瓣后和准分子激光消融后角膜剩余基质床厚度的测量，EX500测量值低于A超的测量值。

METHODS: The CCT of 120 eyes(63 patients)who had LASIK between January 2013 and June 2013 were measured by A-scan and EX500. Three groups were classified: >550μm, 500～550μm, <500μm according the CCT value of A-scan. The CCT were measured again by corneal flap creating by moria SBK microkeratome. The thickness of the corneal bed stroma were measured by A-scan and EX500 after keratomileusis. All outcomes were analyzed with paired t test.

RESULTS: The average preoperative CCT value was 527.9±34.3μm measured by A-scan, 528.5±34.6μm measured by EX500. There was no significant difference between these two measurements(t=1.736, P=0.085). In group which CCT >550μm, the average preoperative CCT value was 571.4±17.3μm measured by A-scan, 572.7±15.7μm measured by EX500. There was no significant difference between these two measurements(t=1.857, P=0.072). In group which CCT 500～550μm, the average preoperative CCT value was 523.4±13.1μm measured by A-scan, 524.2±12.4μm measured by EX500. There was no significant difference between these two measurements(t=1.934, P=0.058). In group which CCT <500μm, the average preoperative CCT value 484.5±9.8μm measured by A-scan, 483.7±8.9μm measured by EX500. There was no significant difference between these two measurements(t=1.395, P=0.174). The average CCT value after corneal flap lifting was 401.3±34.2μm measured by A-scan, 393.4±38.9μm measured by EX500. There was a significant difference between these two measurements(t=6.669, P=0.000). The average thickness of the corneal bed stroma value after keratomileusis was 332.6±38.3μm measured by A-scan, 307.3±37.1μm measured by EX500. There was a significant difference between these two measurements(t=17.165, P=0.000).

CONCLUSION: There is no significant difference between preoperative CCT value measured by A-scan and EX500. After corneal flap lifting and keratomileusis, the CCT value measured by EX500 is smaller than measured by A-scan.