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Accuracy of Measurements With the iCare HOME Rebound Tonometer
Julia Termühlen1, Natasa Mihailovic, Maged Alnawaiseh
1*Department of Ophthalmology, University of Münster, Münster †Center of Ophthalmology, University of Cologne, Cologne ‡Department of Ophthalmology, University of Würzburg, Würzburg, Germany.
Purpose:
To evaluate the accuracy of intraocular pressure (IOP) measurements obtained with the newly available iCare HOME (RTHOME) rebound tonometer compared with the iCare ONE (RTONE) tonometer and Goldmann applanation tonometry (GAT), and possible correlation with central corneal thickness (CCT).
Materials And Methods:
IOP measurements were obtained from 154 patients by an ophthalmologist (doc) using each of the above-mentioned tonometers. In addition, patients (pat) measured their own IOP with the RTHOME and RTONE. The means and SD of results obtained with the different tonometers were compared. Agreement between the tonometers was calculated using the Bland-Altman method.
Results:
Mean IOPs for the right eyes only were 15.9±6.4 mm Hg (RTONEdoc), 15.8±6.4 mm Hg (RTONEpat), 15.0±5.9 mm Hg (RTHOMEdoc), 14.9±6.3 mm Hg (RTHOMEpat), and 15.8±4.4 mm Hg (GAT). Bland-Altman analysis revealed mean differences (bias) between RTONEdoc and RTHOMEdoc, between RTHOMEdoc and RTHOMEpat, and between RTHOMEdoc and GAT of 0.8, 0.1, and -0.8 mm Hg, respectively, with 95% limits of agreement of -3.5 to 5.2, -4.9 to 5.1, and -7.2 to 5.6 mm Hg, respectively. Linear regression of the comparisons revealed a proportional error over the range of pressures examined in the case of RTHOMEdoc versus GAT (slope=0.32, P<0.001). Considering the data from all eyes, the difference between RTHOMEdoc and GAT correlated significantly with the CCT (P=0.01).
Conclusion:
RTHOME readings correlate well with the GAT results although some limitations such as dependency of readings on CCT and increasing differences at lower and higher IOP levels need to be taken into account.
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