圆锥角膜患者双眼角膜生物力学性能的对称性

目的：应用超高频Scheimpflug角膜生物力学分析仪（CorVis-ST）评估双眼圆锥角膜患者角膜生物力学性能的对称性。方法：病例系列研究。于2013 年12 月至2015 年7 月间根据Amsler-Krumeich圆锥角膜分期标准诊断纳入温州医科大学附属眼视光医院视光门诊就诊的双眼圆锥角膜患者40 例（80 眼）。每只受试眼均使用CorVis-ST测量3 次，得到10 项生物力学参数及眼内压（IOP）、中央角膜厚度（CCT）等12项参数。双眼间差异分析采用Student's t检验和Mann-Whitney U检验，双眼一致性分析采用Bland-Altman方法。结果：12个CorVis-ST参数的双眼95%一致性界限分别为：第1次压平时间（AP1 T） -0.56 ~ 0.61 ms（Z=0.441，P =0.229），第1次压平长度-0.75 ~ 0.77 mm（t =-0.178，P =0.907），第1次压平速度-0.063 ~ 0.053 m/s（Z=-1.528，P =0.171），第2次压平时间（AP2 T）-1.01 ~ 0.84 ms（t =-0.848，P =0.269），第2 次压平长度-0.96 ~ 1.02 mm（t =-0.342，P =0.715），第2 次压平速度-0.22 ~ 0.22 m/s（t =-0.087，P =0.812），最大形变时间（T）-1.38 ~ 1.11 ms （Z =-1.170，P =0.162），最大形变峰间距-1.70 ~ 3.93 mm（Z =-3.321，P =0.001），最大形变曲率-2.30 ~ 2.74 mm（t =1.014，P =0.287），最大形变幅度-0.34 ~ 0.28 mm（t =-1.057，P =0.221），眼内压-3.61 ~ 3.91 mmHg（t =-1.152，P =0.267），CCT-136 ~ 152 μm（t =-0.698，P =0.323），双眼间差异除最大形变峰间距外均无统计学意义。对应的一致性比值分别为8.8%、45.0%、37.0%、4.6%、65.8%、50.0%、8.5%、78.8%、46.5%、29.1%、32.6%、32.3%。在12 个参数值中，AP1 T、AP2 T、T一致性比值较小，双眼间有着较高的一致性。结论：AP1 T、AP2 T、T拥有较高的双眼间对称性，在应用CorVis-ST对圆锥角膜患者行角膜生物力学性能研究时，应考虑到双眼间角膜生物力学对称性对结果的影响。

Inter-corneal Biomechanical Symmetry in Keratoconus Patients

Objective:To evaluate inter-corneal symmetry of biomechanical parameters in keratoconus patients as measured by an ultra-high frequency corneal visualization Scheimpflug technology (CorVis-ST).Methods:In this case series study,40 bilateral keratoconus patients diagnosed with the Amsler-Krumeich keratoconus classification were recruited from December 2013 to July 2015 at the Optometry Outpatient of the Eye Hospital,Wenzhou Medical University.The same operator,using the same CorVis-ST instrument,measured each eye three times.Twelve inter-corneal parameters measured by the instrument were recorded,including 10 biomechanical parameters,intraocular pressure,and central corneal thickness.Student's t-test and Mann-Whitney U-test were used to compare inter-corneal differences,while inter-corneal agreement was evaluated by the Bland-Altman plot.Results:The 95％ limits of agreement and agreement ratios of the 12 parameters were as follows:applanation 1 time (AP1 T),-0.56-0.61 ms (8.8％,Z=0.441,P=0.229);applanation 1 length,-0.75-0.77 mm (45.0％,t=-0.178,P=0.907);applanation 1 velocity,-0.063-0.053 m/s (37.0％,Z=-1.528,P=0.171);applanation 2 time (AP2 T),-1.01-0.84 ms (4.6％,t=-0.848,P=0.269);applanation 2 length,-0.96-1.02 mm (65.8％,t=-0.342,P=0.715);applanation 2 velocity,-0.22-0.22 m/s(50.0％,t=-0.087,P=0.812);maximum deformation time (T),-1.38-1.11 ms (8.5％,Z=-1.170,P=0.162);maximum deformation peak distance,-1.70-3.93 mm (78.8％,Z=-3.321,P=0.001);maximum deformation curvature,-2.30-2.74 mm (46.5％,t=1.014,P=0.287);maximum deformation amplitude,-0.34-0.28 mm (29.1％,t=-1.057,P=0.221);intraocular pressure,-3.61-3.91 mmHg (32.6％,t=-1.152,P=0.267);and central corneal thickness,-135.70-152.10 μm (32.3％,t=-0.698,P=0.323).Of all measured parameters,only AP1 T,AP2 T,and T had low agreement ratios,indicating high inter-corneal symmetry.Conclusions:In our study population of binocular keratoconus patients,the parameters AP1 T,AP2 T,and T had high inter-corneal symmetry.Research protocols using the CorVis-ST to study keratoconus should take these results into consideration during data analysis.