Department of Ophthalmology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
Cornea. 2012 Mar;31(3):253-8. doi: 10.1097/ICO.0B013E31823D1EE0.
To investigate the severity of keratoconus in terms of corneal elevation differences with 2 different reference surfaces using topographic analysis.
Eighty-six eyes of 50 patients with keratoconus of various clinical stages (61 male and 25 female eyes) with mean age of 37.3 ± 11.6 years were evaluated. Anterior and posterior corneal elevations were measured using topographic analysis (using a rotating Scheimpflug camera), and the imaging data were analyzed to estimate elevation differences as differential values from conventional best-fit-sphere and enhanced best-fit-sphere (exclusion of a 4-mm-diameter area from the most thinned cornea). The data correlated with the keratoconus severity index and Amsler-Krumeich classification of keratoconus.
There was a significant positive correlation between elevation differences and keratoconus severity index in both anterior and posterior surfaces (Pearson correlation coefficient, r = 0.66; P < 0.001; r = 0.74; P < 0.001). Cases of larger elevation differences in the anterior and posterior corneal surfaces were staged higher in Amsler-Krumeich classification (1-way analysis of variance, P = 0.040; P < 0.001). Cases of lower staging in the Amsler-Krumeich classification had a larger area under the receiver operating characteristic curve in the posterior elevation differences than in the anterior elevation differences, suggesting a greater diagnostic value of the posterior elevation measurement.
Anterior and posterior corneal surface height data obtained by elevation-based tomography provide useful information in improving keratoconus diagnostic accuracy and in grading the severity of keratoconus.
使用地形分析，通过两种不同参考表面的角膜高程差异来研究圆锥角膜的严重程度。
评估了 50 例不同临床阶段（61 例男性和 25 例女性）的圆锥角膜患者的 86 只眼（86 只眼），平均年龄为 37.3 ± 11.6 岁。使用地形分析（使用旋转 Scheimpflug 相机）测量前、后角膜的高度，分析成像数据，估计高度差为常规最佳拟合球和增强最佳拟合球（从最薄角膜排除 4mm 直径区域）的差分值。数据与圆锥角膜严重程度指数和圆锥角膜 Amsler-Krumeich 分类相关。
前、后表面的高度差与圆锥角膜严重程度指数均呈显著正相关（Pearson 相关系数，r = 0.66；P <0.001；r = 0.74；P <0.001）。前、后角膜表面高度差较大的病例在 Amsler-Krumeich 分类中分级较高（单因素方差分析，P = 0.040；P <0.001）。Amsler-Krumeich 分类中分级较低的病例，在后角膜高度差异的受试者工作特征曲线下面积大于前角膜高度差异，表明后角膜高度测量具有更大的诊断价值。
基于高程的断层扫描获得的前、后角膜表面高度数据可提供有用的信息，有助于提高圆锥角膜的诊断准确性和分级严重程度。
