Comparison of the Intraocular Pressure Measured Using the New Rebound Tonometer Icare ic100 and Icare TA01i or Goldmann Applanation Tonometer.

Abstract

We evaluated the agreement between the intraocular pressure (IOP) values of new rebound tonometer, Icare ic100, and Icare TA01i or Goldmann applanation tonometer (GAT). We studied one eye each of 106 subjects (57 with primary open-angle glaucoma, 49 healthy subjects). IOP was randomly measured twice with the patient in sitting position using the Icare ic100, Icare TA01i, and GAT. Tonometer measurements were evaluated using Bland-Altman analysis. The relationship between IOP difference (Icare ic100-GAT) and age, sex, disease, axial length, central corneal thickness (CCT), and corneal curvature was investigated using multivariate regression analysis. IOPs measured using Icare ic100, Icare TA01i, and GAT were 11.7±3.0 (mean±standard deviation), 12.2±2.9, and 16.0±3.2 mm Hg, respectively (P<0.001, one-way analysis of variance). Icare ic100 showed significantly lower IOPs than GAT (P<0.05), but not than Icare TA01 (P>0.05; Tukey-Kramer test). Bland-Altman analysis revealed that the mean differences between Icare ic100 and Icare TA01i and those between Icare ic100 and GAT were -0.46 and -4.2 mm Hg, respectively (95% limits of agreement, -3.35 to 2.42 and -10.10 to 1.61 mm Hg, respectively). For IOP differences between Icare ic100 and GAT, parameters selected in the optimal model were CCT (coefficient, 20.3, P=0.029), corneal curvature (3.0, P=0.020), and glaucoma-normal (-1.0, P=0.004). The new rebound tonometer Icare ic100 almost constantly showed IOPs lower than GAT. The difference was affected by CCT, corneal curvature, and disease.