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Editors Selection IGR 25-2

Clinical Examination Methods: Tono-Vera: a promising new handheld rebound tonometer?

Comment by Lama Assi & Leo Seibold on:

126398 Intraocular Pressure Measurements With the Tono-Vera: A New Handheld Rebound Tonometer, Beniz LAF; Jammal AA; Malek DA et al., Journal of Glaucoma, 2025; 34: 343-348

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While intraocular pressure (IOP) is no longer recognized as a defining feature in glaucoma, it remains the most important modifiable risk factor in its development and progression. In the glaucoma clinic, Goldmann applanation tonometry (GAT) remains the gold standard for measuring IOP.¹ However, it requires trained staff and the use of anesthetic eye drops, and can be influenced by variables such as central corneal thickness (CCT) and surface irregularity. In response to these limitations, other devices and methods of tonometry have been developed with a goal of more automation and accuracy. In certain patients and clinical settings such as community screenings or general eye clinics, these other instruments may be more appropriate.

In this study, the authors compared IOP measurments obtained by Tono-Vera, a new rebound tonometer, to Goldmann-correlated IOP [IOPgc] measurements obtained by the Ocular Response Analyzer (ORA), a noncontact tonometer.² The Tono-Vera is a new device with a positioning system that guides the user to the central cornea with an interactive color display of the eye, making it easier to obtain reproducible measurements. The study authors found that IOP measurements obtained by Tono-Vera and ORA were comparable to each other, among patients with and without open angle glaucoma. They also reported that CCT (among other variables) was not significantly associated with mean difference between measurements obtained by each method. These findings help support its potential viability as an alternative tonometry method.

However, the choice of control significantly limits the usefulness of the study, as it neither compares the device to the gold standard, GAT, nor to previously validated rebound tonometers, such as the iCare. The authors justify their choice by stating that “ORA provides an IOPgc which has been shown in previous studies to agree well with GAT measurements” without citing any evidence.² This is not consistent with current evidence that ORA measurements (including IOPgc) cannot be used interchangeably with those obtained by GAT.^3-5 As stated by the authors, GAT measurements can be limited by operator bias, which could be used to justify using an alternative device as control. However, a more valuable comparison would have been to another well-studied rebound tonometer, with evaluation of technician and patient preference or ease of use.

In conclusion, there is good agreement between IOP measurements from Tono-Vera and ORA, suggesting that Tono-Vera could be used in settings where portable, easy-to-use instruments are valuable. Expanding its use routinely in the glaucoma clinic requires future studies comparing it to GAT and examining the relationship between IOP measurements and glaucoma outcomes.

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