Department of Medicine and Health Sciences, University of Ghent, Ghent, Belgium; Department of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.
Department of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium; Department of Ophthalmology, Antwerp University Hospital, Edegem, Belgium.
Am J Ophthalmol. 2020 Nov;219:154-162. doi: 10.1016/j.ajo.2020.06.013. Epub 2020 Jun 20.
To evaluate the repeatability of an extensive number of relevant indices with the Pentacam HR in keratoconus of varying severity and normal eyes.
Reliability analysis.
This study was performed at Antwerp University Hospital, Belgium, and enrolled 20 healthy volunteers (20 eyes) and 69 patients (69 eyes) with keratoconus. Three consecutive measurements were performed by the same operator with Pentacam HR in keratoconus and normal eyes. Exclusion criteria included past ocular surgery, recent rigid contact lens wear, and corneal scarring. The keratoconus group was subdivided according to the Belin/Ambrosio total deviation value: subclinical, mild, and moderate. The within-subject standard deviation and repeatability limit were computed for repeatability assessment. The tolerance index (TI) was calculated to compare across parameters with different measurement scales. For the sample size included, TI > 0.36 signified statistical significance at the 0.05 level.
Repeatability in subclinical keratoconus did not differ significantly from controls (P > .05), except for wavefront aberrations. In mild keratoconus, 11 of 18 (61.1%) anterior corneal, 7 of 14 (50%) posterior corneal, 2 of 5 (40%) pachymetry, 7 of 11 (63.6%) combined, and 1 of 6 (16.7%) densitometry parameters showed significantly worse repeatability compared to controls (TI > 0.36). Repeatability of most parameters worsened in moderate disease. In particular, maximal keratometry and anterior astigmatism showed significantly worse repeatability in moderate keratoconus.
Measurement variability of Pentacam HR is of clinical relevance when assessing for progression of keratoconus. We provide reference repeatability values and scale independent analysis of relevant corneal parameters in keratoconus of varying degrees.
评估 Pentacam HR 在不同严重程度的圆锥角膜和正常眼中大量相关指标的重复性。
可靠性分析。
本研究在比利时安特卫普大学医院进行，纳入 20 名健康志愿者（20 只眼）和 69 名圆锥角膜患者（69 只眼）。同一位操作者用 Pentacam HR 在圆锥角膜和正常眼中进行了 3 次连续测量。排除标准包括过去的眼部手术、最近佩戴硬性隐形眼镜和角膜瘢痕。圆锥角膜组根据 Belin/Ambrosio 总偏差值分为亚临床、轻度和中度。计算了各向同性标准偏差和重复性限以评估重复性。计算了容差指数（TI）以比较不同测量尺度的参数。对于纳入的样本量，TI>0.36 表示在 0.05 水平上具有统计学意义。
亚临床圆锥角膜的重复性与对照组无显著差异（P>0.05），除了波前像差。在轻度圆锥角膜中，18 个前角膜参数中有 11 个（61.1%）、14 个后角膜参数中有 7 个（50%）、5 个角膜厚度参数中有 2 个（40%）、11 个综合参数中有 7 个（63.6%）和 6 个密度参数中有 1 个（16.7%）的重复性明显比对照组差（TI>0.36）。中度疾病时大多数参数的重复性变差。特别是在中度圆锥角膜中，最大角膜曲率和前散光的重复性明显较差。
在评估圆锥角膜进展时，Pentacam HR 的测量变异性具有临床意义。我们提供了不同程度圆锥角膜相关角膜参数的参考重复性值和与尺度无关的分析。
