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Comparison of ICare Tonometer with Goldmann Applanation Tonometer in Glaucoma Patients

Brusini, Paolo MD; Salvetat, Maria Letizia MD; Zeppieri, Marco MD; Tosoni, Claudia MD; Parisi, Lucia

doi: 10.1097/01.ijg.0000212208.87523.66
Original Articles

Purpose To compare the intraocular pressure (IOP) readings taken with the new ICare tonometer and with the Goldmann applanation tonometer (GAT) and to evaluate the influence of central corneal thickness (CCT) on the IOP measurements.

Patients and Methods One eye of 178 consecutive patients with primary open-angle glaucoma underwent ultrasonic CCT measurement, followed by IOP evaluation with the GAT and with the ICare tonometer. The deviation of ICare readings from GAT values, corrected according to the Doughty and Zaman formula, was calculated and correlated to CCT by a linear regression model. The agreement between the 2 devices was assessed by use of the Bland-Altman method.

Results The average CCT was 552±39 μm. The mean IOP and the mean corrected IOP with GAT were 19.4±5.4 mm Hg, and 18.5±5.7 mm Hg, respectively. The mean ICare IOP reading was 18.4±5.2 mm Hg. The deviations of ICare readings from corrected GAT values were highly correlated with CCT values (r=0.63, P<0.01). Linear regression analysis showed that a CCT change of 10 μm resulted in an ICare reading deviation of 0.7 mm Hg. The Bland-Altman scatter-plot showed a reasonable agreement between the 2 tonometers.

Conclusions The ICare tonometer can be useful in a routine clinical setting. The IOP readings are quite in accordance with those obtained by GAT. The measurements seemed to be influenced by CCT variations, and thus pachymetry should always be taken into consideration.

Department of Ophthalmology, Santa Maria della Misericordia Hospital, Udine, Italy

Reprints: Paolo Brusini, Department of Ophthalmology, Santa Maria della Misericordia Hospital, P. le S. Maria della Misericordia, 15-33100 Udine, Italy (e-mail:

Received for publication March 14, 2005; accepted October 25, 2005

The authors have no proprietary interest in any of the devices used in this study.

© 2006 Lippincott Williams & Wilkins, Inc.