Pentacam系统角膜后表面参数在临床前期圆锥角膜筛查中的作用

The role of the posterior corneal parameters measured by Pentacam in subclinical keratoconus screening

目的探讨Pentacam测量所得的角膜后表面参数对于筛查临床前期圆锥角膜的作用。设计前瞻性病例对照研究。研究对象正常对照组45例73眼,临床期圆锥角膜组14例20眼,临床前期圆锥角膜组43例58眼。方法经TOPOLYZER角膜地形图仪和裂隙灯显微镜检查确诊的临床前期、临床期圆锥角膜组,用Pentacam测量获得角膜后表面参数水平,分别与正常对照组所得的相应参数进行对比。主要指标角膜后表面的高度最大值、高度最小值、高度差、最小矢状曲率、角膜中央3mm平均散光度。结果正常对照组和临床期、临床前期圆锥角膜组间有统计学显著性差异的角膜后表面参数为:角膜后表面的高度最大值(P均<0.001)、高度最小值(P均<0.001)、高度差(P均<0.001)、最小矢状曲率(P<0.001、P=0.014)、角膜中央3mm平均散光度(P<0.001、P=0.008),它们均与圆锥角膜的发展相关,并依照ROC曲线,计算出角膜后表面高度最大值、高度差、角膜中央3 mm平均散光度在区分正常角膜和临床期、临床前期圆锥角膜时的切点、敏感度及特异度。结论Pentacam测量的角膜后表面参数可以有效地筛查临床前期圆锥角膜及确诊临床期圆锥角膜。

Objective To estimate the role of the posterior corneal parameters measured by Pentaeam in screening subclinical keratoeonus. Design Retrospective case-controlled study. Participants Forty five healthy subjects （73 eyes）, 14 keratoconus patients （20 eyes）, 43 subclinieai keratoconus patients （58 eyes）. Methods Based TOPOLYZEB- and biomieroscope signs, eyes were diagnosed as subclinical keratoconus and kcratoconus to compare the differnces of related posterior corneal parameters provided by Pentaeam in normal eyes and subclinical keratoconus or keratoconus eyes. Main Outcome Measures Baek-Diff （6 ram） max, Baek-Diff （6 mm）min, Back-Difference （6 ram）, Back-Rmin, Baek-Astig. Results The parameters which were statistically different between normal corneas and clinical keratoeonus,normal corneas and subclinical keratoconus include Back-Diff（6 ram）marx （P〈0.001）, Back-Diff （6 ram） rain （P〈0. 001）, Back-DiffereHce （6ram） （P〈0.001）, Back-Rmin （P〈0.001, 0.014）, Back-Astig （P〈0.001, 0.008）. ROC eurves were used to identify optimal cutoff points of posterior corneal parameters, which were statistically different in subclinical keratocnnus, keratoeonus and normal eyes, to maximize sensitivity and specificity in discrinfinating keratoeonus and subclinical keratoconus from normal eorneas. Conclusion Pentacam can play a role in screening subclinical keratoconus and diagnosing keratoeonus.