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Abstract #11465 Published in IGR 6-3
Comparison of the Tono-Pen and Goldmann tonometer for measuring intraocular pressure in patients with glaucoma
Horowitz GS; Byles J; Lee J; D'Este CClinical and Experimental Ophthalmology 2004; 32: 584-589
AIM: To estimate agreement between measurement of intraocular pressure (IOP) by the Tono-Pen and by the Goldmann tonometer. The hypothesis tested was that the mean difference in measurements would be < -2 mmHg. METHODS: A prospective, single-centre, comparison study was carried out. The Tono-Pen was compared to the Goldmann tonometer in 138 patients systematically selected from two glaucoma clinics and among selected patients known to have high pressures (n = 22). For both groups the investigators were masked to the value of the Goldmann readings, the instruments were used in random order, and duplicated readings were taken with both tonometers. RESULTS: In the systematically selected group, for right eyes, the mean difference in measurement between the Tono-Pen and Goldmann tonometer was -0.41 mmHg (SD: 2.59). The 95% limits of agreement were -5.5 to 4.7 mmHg, and the intraclass correlation coefficient (ICC) was 0.90. Results for left eyes were very similar. For patients with high pressures (≥ 25 mmHg), the mean difference between instruments (Tono-Pen reading minus Goldmann reading): was -4.2 mmHg (P = 0.0004), SD: 4.6, 95% limits of agreement: -13.2 to 4.8 mmHg and ICC = 0.76. Combining the analysis for both groups, the Tono-Pen significantly underestimated the IOP when the pressure was > 20 mmHg. CONCLUSIONS: The Tono-Pen cannot replace the Goldmann tonometer in the sense that it will give the same readings of IOP. The accuracy of the Tono-Pen is increased, if at least two measurements are taken per eye and then averaged.
Dr. G.S. Horowitz, Sydney Eye Hospital, Sydney, Australia
Classification:
6.1 Intraocular pressure measurement; factors affecting IOP (Part of: 6 Clinical examination methods)
