Faculty of Medicine, Ain Shams University, Cairo, 11799, Egypt.
Al Watani Eye Hospitals, Cairo, Egypt.
Int Ophthalmol. 2021 Feb;41(2):629-638. doi: 10.1007/s10792-020-01618-8. Epub 2020 Oct 23.
Detecting the accuracy of various posterior elevation (PE) indices of Pentacam HR, and correlating them with some possibly related factors or parameters, in a cohort with early keratoconus (KC).
A cross sectional study that was conducted at Eye World Hospital, Egypt. One hundred and two corneas were enrolled, including two groups; group 1 (50 corneas) having forme fruste or early KC, and group 2 (52 corneas) for healthy controls. Corneas were scanned using Pentacam HR (Oculus, Wetzlar, Germany). The investigated PE parameters were: PE from best fit sphere (BFS), PE from best fit toric ellipsoid (BFTE), PE from exclusion map of Belin Ambrosio's display (BAD), and PE from difference map of BAD. The four PE values were correlated to age, thinnest corneal thickness "TCT," posterior aberrations, and posterior Q value.
All the investigated indices were significantly different in group 1 compared to group 2 (p < 0.001). Accuracy of PE parameters revealed the highest AUROC for PE from BFTE (AUROC = 0.989, and best cutoff > 4 um with sensitivity 96.00% and specificity 96.15%). PE from difference map was the least accurate. Correlation coefficients showed a significant correlation between all the studied PE parameters and some of the posterior aberrations (root mean square of higher order aberrations, vertical coma, and spherical aberrations), besides a significant correlation with posterior Q value.
PE indices are sensitive detectors of early ectasia. PE from BFTE had the highest deduced AUROC. Alterations in PE values can significantly alter many posterior corneal aberrations and the posterior Q.
检测 Pentacam HR 中各种后表面高度（PE）指数的准确性，并将其与一些可能相关的因素或参数相关联，在早期圆锥角膜（KC）患者中进行研究。
这是在埃及 Eye World 医院进行的一项横断面研究。共纳入 102 例角膜，分为两组；第 1 组（50 例）为亚临床或早期 KC，第 2 组（52 例）为健康对照组。使用 Pentacam HR（德国 Oculus，Wetzlar）对角膜进行扫描。研究的 PE 参数包括：最佳拟合球（BFS）的 PE、最佳拟合各向异性椭圆体（BFTE）的 PE、Belin Ambrosio 显示排除图（BAD）的 PE 和 BAD 差图的 PE。将这四个 PE 值与年龄、最薄角膜厚度（TCT）、后表面像差和后 Q 值相关联。
与第 2 组相比，第 1 组的所有研究指标均有显著差异（p<0.001）。PE 参数的准确性显示，BFTE 的 PE 具有最高的 AUROC（AUROC=0.989，最佳截断值>4 μm，灵敏度为 96.00%，特异性为 96.15%）。差异图的 PE 最不准确。相关系数显示，所有研究的 PE 参数与某些后表面像差（高阶像差均方根、垂直彗差和球差）之间存在显著相关性，此外还与后 Q 值显著相关。
PE 指数是早期角膜扩张的敏感检测指标。BFTE 的 PE 具有最高的推断 AUROC。PE 值的变化会显著改变许多后表面像差和后 Q 值。
