飞秒激光小切口角膜基质透镜取出术后角膜生物力学变化的影响因素分析

Changes in corneal biomechanical properties and their influencing factors after small incision lenticule extraction

目的 探讨飞秒激光小切口角膜基质透镜取出术(SMILE)术后角膜生物力学特性变化相关的影响因素。方法 回顾性病例对照研究。选取2020年7月至2022年8月于西南医科大学附属医院眼科进行SMILE手术的患者108例203眼,应用Corvis ST测量所有研究对象硬度参数A1(SPA1)、综合半径(IR)、水平方向Ambrósio相关厚度(ARTh)、1 mm范围内形变幅度比(DAR/1 mm)、2 mm范围内形变幅度比(DAR/2 mm)和最大形变幅度(DA),并应用统计学方法分析角膜生物力学参数术后3个月与术前的改变量与年龄、球镜度、柱镜度、等效球镜度(SE)、眼轴长度(AL)、眼压(IOP)、中央角膜厚度(CCT)、残余基质厚度(RST)、RST/CCT、角膜帽厚度(CAP)/CCT、切削厚度和组织改变百分比(PTA)之间的相关性。结果 经相关性分析,PTA与ΔDAR/1 mm(r=0.302,P<0.001)(Δ指术后3个月与术前的改变量)、ΔDAR/2 mm(r=0.355,P<0.001)、ΔARTh(r=0.470,P<0.001)、ΔIR(r=0.501,P<0.001)、ΔSPA1(r=0.318,P=0.016)均呈显著正相关;RST与ΔDAR/1 mm(r=-0.202,P=0.004)、ΔDAR/2 mm(r=-0.365,P<0.001)、ΔARTh(r=-0.244,P<0.001)、ΔIR(r=-0.402,P<0.001)、ΔSPA1(r=-0.169,P=0.016)均呈显著负相关;CAP/CCT与ΔARTh(r=-0.339,P<0.001)、ΔIR(r=-0.141,P=0.044)、ΔSPA1(r=-0.243,P<0.001)均呈显著负相关;AL与ΔARTh(r=0.434,P<0.001)、ΔIR(r=0.245,P=0.001)、ΔSPA1(r=0.336,P<0.001)均呈显著正相关。PTA与ΔIR的6阶拟合曲线提示,当PTA>26%时曲线斜率明显增大。结论 PTA越小、RST越大、CAP/CCT越大,SMILE术后安全性越高,且当PTA>26%时,较小的切削厚度占比增加即可造成SMILE术后较大的角膜生物力学改变。

Objective To analyze the variations of corneal biomechanical properties after small incision lenticule extraction(SMILE)and their influencing factors.Methods In this retrospective case-control study,108 patients(203 eyes)who received SMILE surgery in the Department of Ophthalmology,Affiliated Hospital of Southwest Medical University,from July 2020 to August 2022,were selected.The stiffness parameter at the first applanation(SPA1),integrated radius(IR),Ambrósio’s relational thickness to the horizontal profile(ARTh),deformation amplitude ratio at 1 mm(DAR/1 mm),deformation amplitude ratio at 2 mm(DAR/2 mm),and the maximum deformation amplitude(DA)were measured with Corvis ST.Changes in corneal biomechanical parameters three months after surgery were analyzed using the statistical method,and their correlations with age,spherical power,cylindrical power,spherical equivalent(SE),axial length(AL),intraocular pressure(IOP),central corneal thickness(CCT),residual stromal thickness(RST),RST/CCT,cap thickness(CAP)/CCT,cutting thickness and percent tissue altered(PTA)were discussed.Results Correlation analysis showed that PTA was positively correlated withΔDAR/1 mm(r=0.302,P<0.001)(Δrefers to the change in parameters after SMILE in three months),ΔDAR/2 mm(r=0.355,P<0.001),ΔARTh(r=0.470,P<0.001),ΔIR(r=0.501,P<0.001),andΔSPA1(r=0.318,P=0.016);RST was negatively correlated withΔDAR/1 mm(r=-0.202,P=0.004),ΔDAR/2 mm(r=-0.365,P<0.001),ΔARTh(r=-0.244,P<0.001),ΔIR(r=-0.402,P<0.001),andΔSPA1(r=-0.169,P=0.016);CAP/CCT was negatively correlated withΔARTh(r=-0.339,P<0.001),ΔIR(r=-0.141,P=0.044),andΔSPA1(r=-0.243,P<0.001);AL was positively correlated withΔARTh(r=0.434,P<0.001),ΔIR(r=0.245,P=0.001),andΔSPA1(r=0.336,P<0.001).The 6-order fitting curve about PTA andΔIR indicated that the curve slope increased significantly when PTA exceeded 26%.Conclusion Lower PTA and larger RST and CAP/CCT mean higher safety after SMILE.When PTA exceeds 26%,a mild increase in the cutting thickness ratio may cause significant variations of corneal biomechanical properties after SMILE.