PURPOSE To analyze the potential benefit of the newly developed Tomography and Biomechanical Index (TBI) for early keratoconus screening. METHODS In this retrospective study, the discriminatory power of the corneal tomography Belin/Ambrósio Enhanced Ectasia Display (BAD-D) index and the newly developed Corvis Biomechanical Index (CBI) and TBI to differentiate between normal eyes, manifest keratoconus eyes (KCE), very asymmetric keratoconus eyes with ectasia (VAE-E), and their fellow eyes with either regular topography (VAE-NT) or regular topography and tomography (VAE-NTT) were analyzed by applying the t test (for normal distribution), Wilcoxon matched-pairs test (if not normally distributed), and receiver operating characteristic curve (ROC). The DeLong test was used to compare the area under the ROC (AUROC). Further, the cut-offs of the analyzed indices presented in a study by Ambrósio et al. from 2017 were applied in the study population to enable a cross-validation in an independent study population. RESULTS All indices demonstrated a high discriminative power when comparing normal and advanced keratoconus, which decreased when comparing normal and VAE-NT eyes and further when analyzing normal versus VAE-NTT eyes. The difference between the AUROCs reached a statistically significant level when comparing TBI versus BAD-D analyzing normal versus all included keratoconic eyes (P = .02). The TBI presented with the highest AUROCs throughout all conducted analyses when comparing different keratoconus stages, although not reaching a statistically significant level. Applying the cut-offs presented by Ambrósio et al. to differentiate between normal and VAE-NT in the study population, the accuracy was reproducible (accuracy in our study population with an optimized TBI cut-off: 0.72, with the cut-off defined by Ambrósio et al. 0.67). CONCLUSIONS The TBI enables karatoconus screening in topographical and tomographical regular keratoconic eyes. To further improve the screening accuray, prospective studies should be conducted. [J Refract Surg. 2018;34(12):840-847.].

中文翻译：

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层析成像和生物力学Scheimpflug成像对圆锥角膜的表征：当前指标的验证。

目的分析新开发的层析成像和生物力学指数（TBI）对圆锥角膜早期筛查的潜在益处。方法在这项回顾性研究中，角膜断层扫描Belin /Ambrósio增强性角膜扩张显示（BAD-D）指数以及最新开发的Corvis生物力学指数（CBI）和TBI的辨别力可区分正常眼，圆锥角膜显像（KCE），通过应用t检验（正态分布）分析了非常不对称的圆锥角膜扩张性圆锥角膜眼（VAE-E）和规则形貌（VAE-NT）或规则形貌和断层扫描（VAE-NTT）的另一只眼睛，Wilcoxon匹配对测试（如果不是正态分布的话）和接收器工作特性曲线（ROC）。使用DeLong测试比较ROC（AUROC）下的面积。进一步，Ambrósio等人在一项研究中提出的分析指标的临界值。自2017年起将其应用于研究人群中，以在独立研究人群中进行交叉验证。结果当比较正常和晚期圆锥角膜时，所有指数均显示出较高的鉴别力，当比较正常和VAE-NT眼时以及分析正常与VAE-NTT眼时，该指数均降低。当比较TBI与BAD-D来分析正常的和所有包括的圆锥形圆锥眼时，AUROC之间的差异达到了统计学上的显着水平（P = .02）。在比较不同的圆锥角膜分期时，尽管没有达到统计学上的显着水平，但TBI在所有进行的分析中呈现出最高的AUROC。应用Ambrósio等人提出的临界值。为了在研究人群中区分正常人群和VAE-NT，准确性是可重复的（在我们的研究人群中，优化的TBI临界值：0.72，Ambrósio等人定义的临界值为0.67）。结论TBI可以在地形和断层常规圆锥角膜眼睛中进行圆锥角膜筛查。为了进一步提高筛查的准确性，应该进行前瞻性研究。[J Refract Surg。2018; 34（12）：840-847。]。