Khanal Safal, Walton Meredith, Davey Pinakin Gunvant
School of Optometry and Vision Science, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand.
Heights Optometry, San Diego, California, USA.
Clin Exp Optom. 2017 Mar;100(2):179-183. doi: 10.1111/cxo.12454. Epub 2016 Oct 4.
The aims of this study were to evaluate the intra- and inter-observer repeatability of intraocular pressure (IOP) estimates obtained using an iCare rebound tonometer and to investigate the variation in IOP measurements due to positional differences in probe placement on the cornea.
The IOP estimates were obtained by two observers, twice on one eye, of 114 subjects using an iCare tonometer on the central cornea. Additionally, IOP and corneal thickness were measured in 38 subjects at three locations, namely, central, at 1.5 mm nasally and at 1.5 mm temporally from the central cornea. Agreement among measurements was assessed using Bland and Altman plots and the difference in measurements obtained by the observers was compared using paired t-test. Values obtained from central, nasal and temporal regions were compared using one-way analysis of variance.
The mean IOP measurements obtained by observer 1 on two attempts were 16.2 and 16.0 mmHg (p > 0.05) were significantly different from the IOP values obtained by observer 2 on two occasions (16.3 and 15.7 mmHg; p < 0.0001). The limits of agreement (LOA) of intra-observer repeatability were -2.9 to +2.6 mmHg and -3.4 to +2.2 for observers 1 and 2, respectively. The LOA of inter-observer repeatability for first and second sequences were -2.8 to +3.0 mmHg and -3.3 to +2.7 mmHg with the second sequence of measurements being significantly different (p = 0.03). Although the corneal thickness was significantly greater nasally and temporally, when compared to the central location, by 32 and 20 microns respectively (p < 0.0001), the measured IOPs on those locations were not significantly different, when compared to the central measurements (p = 0.14).
There is good intra- and inter-observer repeatability of IOP data, as obtained by the iCare rebound tonometer, although the results may be slightly influenced by practitioner experience. The difference in IOP estimates obtained by different observers is unlikely to be of clinical significance. Corneal thickness showed regional variation; however, this did not influence IOP measurements obtained from those locations.
本研究旨在评估使用Icare回弹式眼压计获得的眼压（IOP）估计值在观察者内和观察者间的重复性，并研究由于角膜上探头放置位置不同导致的眼压测量差异。
114名受试者的一只眼睛由两名观察者使用Icare眼压计在中央角膜上测量两次眼压估计值。此外，对38名受试者在中央角膜、中央角膜鼻侧1.5毫米处和中央角膜颞侧1.5毫米处三个位置测量眼压和角膜厚度。使用Bland和Altman图评估测量值之间的一致性，并使用配对t检验比较观察者获得的测量值差异。使用单因素方差分析比较从中央、鼻侧和颞侧区域获得的值。
观察者1两次测量获得的平均眼压值分别为16.2和16.0 mmHg（p>0.05），与观察者2两次测量获得的眼压值（16.3和15.7 mmHg；p<0.0001）有显著差异。观察者1和观察者2的观察者内重复性一致性界限（LOA）分别为-2.9至+2.6 mmHg和-3.4至+2.2 mmHg。第一次和第二次测量序列的观察者间重复性LOA分别为-2.8至+3.0 mmHg和-3.3至+2.7 mmHg，第二次测量序列有显著差异（p=0.03）。尽管与中央位置相比，鼻侧和颞侧的角膜厚度分别显著增加32和20微米（p<0.0001），但与中央测量值相比，这些位置的测量眼压无显著差异（p=0.14）。
Icare回弹式眼压计获得的眼压数据在观察者内和观察者间具有良好的重复性，尽管结果可能会受到从业者经验的轻微影响。不同观察者获得的眼压估计值差异不太可能具有临床意义。角膜厚度显示出区域差异；然而，这并未影响从这些位置获得的眼压测量值。
