Purpose

To evaluate the diagnostic ability of the ratio of anterior and posterior corneal surface areas (As/Ps) comparing with other keratoconus screening indices in distinguishing forme fruste keratoconus (FFKC) from normal eyes.

Methods

In this comparative study, 13 eyes of 13 patients with FFKC, 29 eyes of 29 patients with keratoconus (KC) and 88 eyes of 88 patients with normal subjects were involved.

The As/Ps measured by the anterior segment optical coherence tomography (AS-OCT) and other indices measured by AS-OCT and rotating Scheimpflug–based corneal tomography were evaluated. The area under receiver-operating-characteristics (AU-ROC) was calculated to assess the diagnostic ability in discriminating FFKC from normal eyes.

Results

The As/Ps, the Belin/Ambrosio display enhanced ectasia total derivation value (BAD-D) and posterior and anterior elevation values showed the AU-ROC 0.9 or more in differentiating FFKC from normal eyes (0.980, 0.951, 0.924 and 0.903, respectively). The sensitivity and specificity were 0.92 and 0.96 for the As/Ps, 1.00 and 0.90 for BAD-D, 0.85 and 0.86 for posterior elevation value, and 0.85 and 0.96 for anterior elevation value, respectively.

Conclusions

Among the several indices for keratoconus screening which we evaluated, the As/Ps obtained by AS-OCT had the large AU-ROC with high sensitivity and specificity in detecting FFKC, which was comparable with BAD-D obtained by rotating Scheimpflug–based corneal tomography. The As/Ps may provide information for improving the diagnostic accuracy of KC, even in the initial stage of the disease.

中文翻译：

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角膜表面积的前后比率：用于检测早期圆锥角膜的新指标。

目的

为了评估与其他圆锥角膜筛查指标相比，角膜前和后角膜表面积比（As / Ps）的诊断能力，以区分正常人眼的圆锥角膜圆锥角膜（FFKC）。

方法

在这项比较研究中，涉及13眼FFKC患者的13眼，29例圆锥角膜（KC）患者的29眼和88例正常受试者的88眼。

评估了通过前段光学相干断层扫描（AS-OCT）测量的As / P，以及通过AS-OCT和基于Scheimpflug的旋转角膜断层扫描测量的其他指标。计算接收器操作特征（AU-ROC）下的面积，以评估区分FFKC和正常眼睛的诊断能力。

结果

As / Ps，Belin / Ambrosio表现出增强的扩张期总衍生值（BAD-D），前后正值表明FFKC与正常眼睛的区别是AU-ROC 0.9或更高（分别为0.980、0.951、0.924和0.903） ）。As / Ps的敏感性和特异性分别为0.92和0.96，BAD-D的敏感性和特异性分别为1.00和0.90，后部升高值分别为0.85和0.86，前部升高值分别为0.85和0.96。

结论

在我们评估的数个圆锥角膜筛查指标中，AS-OCT获得的As / P具有较大的AU-ROC，对FFKC的检测具有很高的灵敏度和特异性，这与通过旋转基于Scheimpflug的角膜层析成像获得的BAD-D相当。即使在疾病的初始阶段，As / Ps仍可为改善KC的诊断准确性提供信息。