Comparison of ICare, Dynamic Contour Tonometer, and Ocular Response Analyzer with Goldmann Applanation Tonometer in Patients with Glaucoma

Abstract

To compare the intraocular pressure (IOP) readings taken by ICare, Pascal dynamic contour tonometer (DCT), and ocular response analyzer (ORA) with those taken by Goldmann applanation tonometer (GAT). We sought to evaluate the influence of central corneal thickness (CCT) on IOP measurements and to compare patients' preferences for the four tonometers. In this prospective study, 93 eyes from 93 patients were examined. Patients were randomly divided into 4 groups to vary the order in which the tonometers were applied. CCT was measured with an ultrasound pachymeter. The average CCT was 558+/-47.4 microm. The mean +/- standard deviation IOP for GAT, ICare, DCT, and ORA (Goldmann-correlated IOP) (ORA(GC)) were 15.1+/-4.8, 15.7+/-5.7, 18.2+/-5.1, and 18.3+/-6.6 mmHg, respectively. There was no significant difference between the mean IOP obtained with GAT and ICare (p=0.14). There was also no difference in IOP levels between the mean IOP obtained with DCT and ORA (p=0.26). There was no correlation between IOP measurements and CCT for the 4 instruments. Bland-Altman graphs showed disagreement between the measurements taken by GAT and the other instruments. There was no significant difference in patients' preference among the 4 instruments (p=0.48). IOP readings from ICare were consistent with those from GAT, whereas DCT readings correspond well to ORA(GC) measurements. DCT and ORA readings both overestimated the GAT readings. There was no correlation between the IOP measurements and the CCT for the 4 instruments. There was no significant difference in patients' preference among the 4 instruments.