Abstract

P 168

A comparison of the iCare and the Perkins tonometer at the lying patient

Jordan J. F., Schild A., Schröter S., Krieglstein G. K., Dietlein T. S.
University Eye Hospital Cologne, Cologne

Objective: The Perkins tonometer is the standard for applanation tonometry in the supine position. The iCare rebound tonometer is a new, handheld device to digitally measure intraocular pressure (IOP) without topical anaesthetics. In contrast to Perkins tonometry, manual tuning for IOP measurement is not necessary. In this study, we investigate the practicability and agreement of the two methods, as well as the dependence of the obtained values on central corneal thickness.
Methods: 76 consecutive eyes of 38 patients were included into this prospective, clinical study. IOP measurement using the Perkins tonometer was performed in the supine position. iCare measurements were taken with the patients in the right or left lateral position, as this tonometer has to be held upright (mean out of six measurements). Central conrneal thickness (CCT) was measured using optical low coherence reflectometry before. Eyes presenting with corneal pathologies were excluded.
Results: Mean central corneal thickness was 534µm (min. 460µm - max. 611µm). Perkins tonometry for the right eye (OD) was mean 18,8±5mmHg, for the left eye (OS) 19,4±5,7mmHg. iCare tonometry for the right eye was mean 19,9±5,7mmHg in the right lateral position (RLP), and 19,6±6mmHg in the left lateral position (LLP). For the left eye, it was 20,5±6,2mmHg in the RLP and 20,4±6,7mmHg in the LLP, respectively. Differences between the eyes and between positions were not significant (t-test). Correlation between iCare and central corneal thickness was 0.27 (non-parametric Spearman correlation), and 0.25 between Perkins and CCT. There was very good agreement between the two methods (correlation coefficient 0.90).
Conclusions: The iCare tonometer proved to be a reliable and reproducible method for measuring IOP in patients lying in bed. There was very good agreement with the measurements obtained by the Perkins tonometer. For the pachymetric range investigated, both devices were almost equally influenced by central corneal thickness.

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