What question did this study set out to answer?

This research aims to evaluate differences in intraocular pressure measurements using three tonometry methods in glaucoma patients.

April 5, 2026Open Access

Cross-sectional observational study comparing intraocular pressure measurements taken with three different methods of tonometry

Key Points

This research aims to evaluate differences in intraocular pressure measurements using three tonometry methods in glaucoma patients.
Cross-sectional comparative design involving 80 patients with suspected POAG
Three tonometers compared: iCare IC200, Goldmann applanation tonometry, and Tono-Pen AVIA
Statistical analysis conducted with paired t-tests and linear mixed models
160 eyes analyzed, with 51 women and 29 men
No significant difference between Goldmann tonometry and iCare IC200
Tono-Pen AVIA tended to understate intraocular pressure compared to Goldmann tonometry

Abstract

Objective: To determine if there is a statistical difference in the measurement of intraocular pressure (IOP) between the rebound tonometer iCare IC200 (iCare Finland Oy, Vantaa, Finland), Goldmann applanation tonometry (GAT) and portable digital hand-held tonometer Tono-Pen AVIA (Reichert, Inc., Depew, NY, USA) in patients with suspected glaucoma or open-angle glaucoma (POAG).Method: Cross-sectional comparative study with 80 patients from the glaucoma clinic of the Mexican Institute of Ophthalmology, adults, with a diagnosis of POAG or suspected glaucoma, without previous eye surgery, keratometries between 500-600 mm and corneal astigmatism less than 3 diopters.A paired t-test analysis was performed, as well as a linear mixed model with the three independent variables adjusting for the individual effect, presented by means of a boxplot with all observations.Results: A total of 160 eyes out of 80 patients were analyzed, of which 51 were women (63.75%) and 29 men (36.25%).When performing the univariate and multivariate comparison between the tonometers, it is concluded that there was no significant difference between the GAT and the iCare IC200, not being the case with the Tono-Pen AVIA and the GAT.Conclusions: This study shows that the iCare IC200 tonometer is a comparable instrument in its measurement of IOP with the GAT in this group of patients, while the Tono-Pen AVIA tonometer shows a tendency towards underestimation.

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