Schwenteck T, Knappe M, Moros I
Klin Monbl Augenheilkd. 2012 Sep;229(9):917-27. doi: 10.1055/s-0031-1299536. Epub 2012 Sep 12.
Golmann applanation tonometry represents a well-established procedure for measuring intraocular pressure (IOP). This implies the necessity of an accurate measurement of IOP with the reference tonometer. One example is the contour tonometer Pascal with a measuring probe, adapted to the cornea geometry, for measuring the IOP and the ocular pulse amplitude. There is controversy of how strongly corneal thickness affects the measurement of IOP. We thus analysed, for a number of eyes, the correlation of IOP, as measured by two types of applanation tonometers and one contour tonometer and the central corneal thickness.
In all 158 patient eyes were investigated in a clinical comparison of applanation tonometers AT 870 and Ocuton-A. The study was performed by a trained ophthalmologist and the comparison was in accordance with international standard ISO 8612. In addition, the corneal thickness in the vertex was repeatedly determined using an Oculus Pentacam. The potential effect of central corneal thickness on the IOP as measured by the mentioned tonometers was statistically evaluated by rank correlation analysis.
We found that the measured IOP values for the three investigated tonometers were not normally distributed. The central corneal thickness values, in contrast, measured on 158 eyes by means of an ultrasound pachymeter and additionally on 235 eyes by the Pentacam, obeyed a Gaussian distribution. For the correlation analysis of both parameters the Spearman linear rank correlation coefficient (r) was considered. We found a very weak (|r| < 0.2) correlation between central corneal thickness and IOP for all 3 tonometers. The softness of the correlation is also illustrated by a large standard deviation of the regression line. A comparison of the different devices for corneal-thickness measurements shows less variance and a smaller variation coefficient when the ultrasoundpachymeter AL-1000 is used.
The measured values for IOP are only very weakly correlated to the central corneal thickness. For the 3 tonometer types studied there is no need to correct the indicated pressure values according to the central corneal thickness of the investigated eye. Clinical comparisons according to the ISO 8612 standard between a tonometer under test and a reference Goldmann applanation tonometer are always a time-consuming procedure. Additional measures to determine the central corneal thickness of every investigated eyes are dispensable.
Goldmann压平眼压计是一种成熟的测量眼压（IOP）的方法。这意味着需要使用标准眼压计准确测量眼压。一个例子是带有测量探头的轮廓眼压计Pascal，该探头可适应角膜几何形状，用于测量眼压和眼脉搏振幅。角膜厚度对眼压测量的影响程度存在争议。因此，我们分析了多只眼睛的眼压（通过两种压平眼压计和一种轮廓眼压计测量）与中央角膜厚度之间的相关性。
在一项对压平眼压计AT 870和Ocuton - A的临床比较中，共对158只患者眼睛进行了研究。该研究由一名训练有素的眼科医生进行，比较符合国际标准ISO 8612。此外，使用Oculus Pentacam反复测量角膜顶点的厚度。通过等级相关分析对中央角膜厚度对上述眼压计测量的眼压的潜在影响进行统计学评估。
我们发现，三种被研究眼压计测量的眼压值并非呈正态分布。相比之下，通过超声测厚仪在158只眼睛上以及通过Pentacam在另外235只眼睛上测量的中央角膜厚度值服从高斯分布。在对这两个参数进行相关分析时，考虑了Spearman线性等级相关系数（r）。我们发现，对于所有三种眼压计，中央角膜厚度与眼压之间的相关性都非常弱（|r| < 0.2）。回归线较大的标准差也说明了这种相关性的微弱程度。当使用超声测厚仪AL - 1000进行角膜厚度测量时，不同测量设备之间的比较显示出较小的方差和变异系数。
眼压测量值与中央角膜厚度之间的相关性非常弱。对于所研究的三种眼压计类型，无需根据被检查眼睛的中央角膜厚度校正所显示的压力值。根据ISO 8612标准，在被测眼压计与参考Goldmann压平眼压计之间进行临床比较始终是一个耗时的过程。确定每只被检查眼睛中央角膜厚度的额外措施是不必要的。
