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Evaluation of a rebound tonometer (Tonovet |
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| Authors: | Elina Rusanen† Marion Florin† Michael Hässig‡ Bernhard M Spiess† |
| Institution: | Department of Equine and Small Animal Medicine, Section of Surgery, University of Helsinki, Helsinki, Finland;, Equine Department, Section of Ophthalmology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland;, Department of Farm Animals, Section of Herd Health, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland |
| Abstract: | Objective To determine the accuracy of and to establish reference values for a rebound tonometer (Tonovet Procedures Six enucleated eyes were used to compare both tonometers with direct manometry. Intraocular pressure (IOP) was measured in 100 cats to establish reference values for rebound tonometry. Of these, 22 cats were used to compare rebound tonometry with and without topical anesthesia and 33 cats to compare the rebound and applanation tonometers. All evaluated eyes were free of ocular disease. Results Both tonometers correlated well with direct manometry. The best agreement with the rebound tonometer was achieved between 25–50 mmHg. The applanation tonometer was accurate at pressures between 0 and 30 mmHg. The mean IOP in clinically normal cats was 20.74 mmHg with the rebound tonometer and 18.4 mmHg with the applanation tonometer. Topical anesthesia did not significantly affect rebound tonometry. Conclusions As the rebound tonometer correlated well with direct manometry in the clinically important pressure range and was well tolerated by cats, it appears suitable for glaucoma diagnosis. The mean IOP obtained with the rebound tonometer was 2–3 mmHg higher than that measured with the applanation tonometer. This difference is within clinically acceptable limits, but indicates that the same type of tonometer should be used in follow-up examinations in a given cat. |
| Keywords: | applanation tonometry cat direct manometry intraocular pressure rebound tonometry |