Purpose:
To evaluate the agreement of iCare rebound tonometer in measuring intraocular pressure (IOP) with Goldmann applanation tonometer (GAT), Tonopen XL, and noncontact air-puff tonometer (Topcon CT-10), as well as the influence of the central corneal thickness (CCT) and mean keratometry (mean KT) on IOP measurement differences.
Methods:
One randomly selected eye of 43 glaucoma patients underwent a sequence of IOP measurements with four different tonometers (iCare, GAT, Tonopen, and air-puff) in a random order, with a 2-minute interval between measurements. IOP measurements from iCare were compared with the other three tonometers. Mean keratometry and central corneal thickness were used to evaluate the influence of corneal parameters on IOP reading differences.
Results:
A total of 43 eyes from 23 female and 20 male glaucoma patients were studied. The mean (SD) IOP measurements obtained with iCare, GAT, Tonopen, and air-puff were 16.2 (5.9) mmHg, 15.8 (4.7) mmHg, 19.5 (4.9) mmHg, and 17.9 (4.3) mmHg, respectively. IOP reading differences between tonometers are shown in the Table. The mean (SD) keratometry was 43.76 (1.31) diopters and the mean (SD) central corneal thickness 545.2 (33.0) µm. There were weak correlations between IOP reading differences and CCT (r varied from 0.13 to 0.43) and mean keratometric values (r varied from -0.31 to 0.15).
Conclusions:
There was a poor agreement between iCare measurements and GAT, Tonopen, and air-puff IOP measurements. Central corneal thickness and mean keratometry were weakly correlated with these IOP differences.
Keywords: intraocular pressure • clinical (human) or epidemiologic studies: systems/equipment/techniques