亚临床期圆锥角膜在Pentacam和orbscan-Ⅱ中角膜地形图指标的差异分析

Differences in topographic map index analyses of normal and subclinical keratoconus eyes obtained with Pentacam and Orbscan-Ⅱ

目的 应用Pentacam和Orbscan-Ⅱ对比分析正常眼与亚临床期圆锥角膜眼的角膜地形图差异,为寻找Pentacam和orbscan-Ⅱ筛查和诊断亚临床期圆锥角膜的敏感地形图指标提供依据.方法 横断面研究.选取正常对照组30例（30眼）和亚临床期圆锥角膜组22例（22眼）,分别行Pentacam和Orbscan-Ⅱ检查.对7个共同的地形图指标包括角膜最薄点厚度（TP）、前表面最小曲率（K1）、前表面最大曲率（K2）、角膜前表面最佳拟合球面曲率半径（ABFS）、角膜后表面最佳拟合球面曲率半径（PBFS）、角膜前表面高度（前Diff值）和角膜后表面高度（后Diff值）进行分析比较.同一检测指标在正常对照组及亚临床期圆锥角膜组间的比较用秩和检验（资料非正态分布）.Orbscan-Ⅱ和Pentacam两仪器间的对比用两个相关样本比较的秩和检验（资料非正态分布）.结果 Pentacam和Orbscan-Ⅱ的7个共同的地形图指标在正常对照组和亚临床期圆锥角膜组之间有明显的差异（P＜0.01）;正常对照组Pentacam和Orbscan-Ⅱ检测值比较,前表面K1、前Diff值、后Diff值差异有统计学意义（P＜0.01）.亚临床期圆锥角膜组Pentacam和Orbscan-Ⅱ检测值比较,TP、前Diff值及后Diff值差异有统计学意义（P＜0.01）.结论 TP、K1、K2、ABFS、PBFS、角膜前Diff值及角膜后Diff值与圆锥角膜的发展密切相关;Pentacam与Orbscan-Ⅱ相比,Pentacam在测量与高度有关的指标时优势明显,尤其是测量后表面的高度时。

Objective To compare corneal topography index measurements of normal and subclinical keratoconus eyes obtained with Pentacam and Orbscan-Ⅱ,providing evidence for seeking a sensitive index with the 2 instruments to identify subclinical keratoconus.Methods Thirty uormal eyes from 30 participants and 22 subclinical keratoconus eyes from 22 participants were included for measurements with Pentacam and Orbscan-Ⅱ for a retrospective analysis.The differences between normal and subclinical keratoconus eyes were compared for the 7 common corneal topography indexes measured by Pentacam and Orbscan-Ⅱ.The measurements included corneal thickness of the thinnest point （TP）,the minimum curvature of the front surface （K1）,the maximum curvature of the front surface （K2）,the anterior corneal surface best fit spherical radius of curvature （ABFS）,the posterior surface of the cornea behind the best fit spherical radius of curvature （PBFS）,the anterior corneal surface height （front Diff value） and the posterior corneal surface height （posterior Diff value）.A rank sum test was used to compare the same parameters between Pentacam and Orbscan-Ⅱ （dates were non-normally distributed）.The test was also used to compare two related samples obtained by the 2 instruments （dates were non-normally distributed）.Results The 7 common parameters measured with Pentacam and Orbscan-Ⅱ showed obvious differences between the normal and subclinical groups.Thus,the 7 parameters have significance in the diagnosis of keratoconus.There were significant differences between Pentacam and Orbscan-Ⅱ in the topography indexes for the normal group （P〈0.01） for K1,front Diff value （P〈0.01）,and posterior Diff value （P〈0.01）.For the subclinical group,there were statistically significant differences （P〈0.01） for TP,front Diff value （P〈0.01） and posterior Diff value （P〈0.01）.Conclusion TP,K1,K2,ABFS,PBFS,front Diff value and posterior Diff value are closely related to the development of keratoconus.Pentacam has an advantage compared to Orbscan-Ⅱ in the measurement of indexes for the surface height,except for the posterior surface.