目的:研究3种角膜屈光手术在手术前后角膜生物力学的变化及不同术式间的差异.方法:前瞻性研究.对2016年2-4月南京医科大学附属南京医院眼科行准分子激光手术的患者64例(125眼)手术前后的角膜生物力学参数进行分析,其中55眼行飞秒激光制瓣准分子激光原位角膜磨镶术(FS-LASIK),47眼行准分子激光前弹力层下角膜磨镶术(SBK),23眼行准分子激光上皮下角膜磨镶术(LASEK).应用可视化角膜生物力学仪(CST)对患者进行测量,选取其中第一压平时间(AT1)、第二压平速度(Vout)、最大压陷曲率半径(HC-radius)、最大压陷幅度(DA)、眼压(IOP)进行分析.术后1d、1周、3个月进行随访.采用单因素方差分析、Pearson相关分析、配对t检验进行数据分析.结果:FS-LASIK组中各项生物力学参数与中央角膜厚度(CCT)(AT1∶ r=0.455,P＜0.001;Vout∶ r=-0.286,P=0.034;HC-radius∶ r=0.357,P=0.007;DA∶ r=-0.341,P=0.011;IOP:r=0.436,P=0.001)、角膜剩余基质床厚度(RST)(AT1∶ r=0.563,P＜0.001;Vout∶ r=-0.417,P=0.007;HC-radius∶ r=0.552,P＜0.001;DA∶r=-0.395,P=0.012;IOP∶ r=0.516,P＜0.001)、最大切削深度(AD)(AT1:r=-0.721,P＜0.001;Vout:r=0.466,P=0.002;HC-radius∶r=-0.407,P=0.009;DA∶r=0.596,P＜0.001;IOP∶ r=-0.612,P＜0.001)均有较强相关性.SBK组中各项生物力学参数均与CCT (AT1∶ r=0.364,P=0.012;Vout∶ r=0.408,P=0.004;HC-radius∶ r=0.326,P=0.025;DA∶ r=-0.362,P=0.012;IOP∶ r=0.387,P=0.007)有较强的相关性.LASEK组中仅AT1(r=0.625,P=0.001)、IOP(r=0.624,P=0.001)与CCT有相关性.3组的AT1、HC-radius、IOP和CCT较术前均减小(均P＜0.05),Vout、DA较术前均增加(均P＜0.05).3组间比较,术后1周时FS-LASIK组的AT1、IOP值明显大于LASEK组(AT1∶ F=7.313,P=0.001;IOP∶ F=4.979,P=0.009),Vout和DA值明显小于LASEK组(Vout∶ F=3.420,P=0.038;DA∶ F=9.024,P＜0.001),SBK组的各项参数值位于2组之间,与FS-LASIK组差异无统计学意义;术后3个月时,3组间差异无统计学意义.结论:在角膜厚度足够时,3种手术方式均能安全可靠地矫正近视.FS-LASIK由于飞秒激光切削的精确性和优越性,术后能够更快恢复生物力学的稳定性.LASEK的生物力学变化与剩余基质床厚度和切削深度的相关性较低,在患者近视度数较高,角膜相对较薄时,可以优先考虑该术式.%Objective:To study the influence of three different corneal refractive surgeries on corneal biomechanics.Methods:Sixty-four patients (125 eyes) were enrolled in this prospective case series study during February 2016 to April 2016.Fifty-five eyes underwent femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK),47 eyes underwent sub-Bowman's keratomileusis (SBK) and 23 eyes underwent laser epithelial keratomileusis (LASEK).AT1,Vout,HC-radius,DA,IOP,and CCT were obtained with a Corvis ST 1 day,1 week,and 3 months postoperatively.One way ANOVA,Pearson,correlation,paired t test were used to analyze data.Results:The biomechanical parameters in the FS-LASIK group were significantly correlated with CCT (Ar1∶ r=0.455,P＜0.001;Vout∶ r=-0.286,P=0.034;HC-radius∶ r=0.357,P=0.007;DA∶r=-0.341,P=0.011;IOP∶ r=0.436,P=0.001),with RST (AT1∶ r=0.563,P＜0.001;Vout∶ r=-0.417,P=0.007;HC-radius∶ r=0.552,P＜0.001;DA∶ r=-0.395,P=0.012;IOP∶ r=0.516,P＜0.001) and with AD (AT1∶r=-0.721,P＜0.001;Vout∶ r=0.466,P=0.002;HC-radius∶ r=-0.407,P=0.009;DA∶ r=0.596,P＜0.001;IOP∶r=-0.612,P＜0.001).The biomechanical parameters in the SBK group were strongly correlated with CCT (Ar1∶ r=0.364,P=0.012;Vout∶ r=0.408,P=0.004;HC-radius∶ r=0.326,P=0.025;DA∶ r=-0.362,P=0.012;IOP∶ r=0.387,P=0.007).For LASEK,only An (r=0.625,P=0.001),IOP (r=0.624,P=0.001) correlated with CCT.For the 3 groups,An,HC-radius,IOP and CCT decreased compared with preoperative values;Vout and DA increased compared with preoperative values (AT1∶ F=7.313,P=0.001;IOP∶ F=4.979,P=0.009).The values of Ar1 and IOP in the FS-LASIK group were significantly greater than those in the LASEK group.Vout and DA were significantly lower than the values in the LASEK group at 1 week after surgery (Vout∶F=3.420,P=0.038;DA∶ F=9.024,P＜0.001).The values of the SBK group were moderate and between the two other groups and compared with the FS-LASIK group difference was not statistically significant.There were no significant differences between the three groups three months after surgery.Conclusions:All three procedures are safe and reliable for the treatment of myopia at a sufficient corneal thickness.For FS-LASIK,biomechanical stability is restored faster after surgery because of the accuracy and superiority of femtosecond laser cutting.LASEK biomechanical changes and residual matrix bed thickness and depth have a low correlation in patients with severe myopia when the cornea is relatively thin.
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