Comparison of three methods of tonometry in normal subjects: Goldmann applanation tonometer, non-contact airpuff tonometer, and Tono-Pen XL

Abstract

Ihsan Yilmaz, Cigdem Altan, Ebru Demet Aygit, Cengiz Alagoz, Okkes Baz, Sibel Ahmet, Semih Urvasizoglu, Dilek Yasa, Ahmet DemirokBeyoglu Eye Training and Research Hospital, Istanbul, TurkeyObjective: We aimed to compare intraocular pressure (IOP) measurements via three different tonometers: the Goldmann applanation tonometer (GAT), the Tono-Pen® XL (TPXL), and a non-contact airpuff tonometer (NCT).Methods: This was a cross-sectional study of 200 eyes from 200 patients. Right eyes of all patients were included in this study. IOP was measured via GAT, NCT, and TPXL by three physicians. Each physician used one of the tonometers. Measurements via the three devices were compared.Results: The mean IOP was 15.5±2.2 mmHg (range 10–22) with the GAT, 16.1±3.0 (range 9–25) with the TPXL, and 16.1±2.8 (range 10–26) with the NCT. Bland–Altman analysis showed that the mean difference between measurements from the NCT and the GAT was 0.6±2.3 mmHg. The mean difference between the TPXL and GAT measurements was 0.7±2.5 mmHg. The mean difference between the NCT and TPXL measurements was −0.02±3.0 mmHg. There was no significant difference between the groups according to a one-way analysis of variance (ANOVA) test. P-values were 0.998 for NCT–TPXL, 0.067 for NCT–GAT, and 0.059 for TPXL–GAT.Conclusion: The NCT and TPXL provide IOP measurements comparable to those of the gold standard GAT in normotensive eyes.Keywords: tonometry, noncontact tonometry, Goldmann applanation tonometer, Tono-Pen