Agreement of rebound tonometer in measuring intraocular pressure with three types of applanation tonometers

PURPOSE: To evaluate the agreement of iCare rebound tonometer in measuring intraocular pressure (IOP) with Goldmann applanation tonometer (GAT), Tonopen XL, and noncontact tonometer, and the influence of the central corneal thickness (CCT) on IOP measurements made with these four tonometers in 45 (12 control and 33 glaucomatous or ocular hypertensive) eyes. DESIGN: Clinically relevant experimental study. METHODS: Tonometer intermethod agreement was assessed by the Bland-Altman method. The relations of CCT with absolute IOP values and intertonometer differences were analyzed by linear regression. RESULTS: The mean differences (95% limits of agreement) in IOP readings between iCare and GAT, Tonopen XL, and noncontact tonometer were 1.40 +/- 4.29, 0.00 +/- 4.78, and 2.22 +/- 4.19 mm Hg, respectively. All tonometries had a marked association with CCT. As the CCT got thicker, iCare considerably overestimated GAT and Tonopen XL. CONCLUSIONS: Although influenced by CCT, iCare agrees well with applanation tonometers.