Comparison of measurement performance among Tono-Vera vet, Tono-Pen vet, and Tono-Vet plus using an ex vivo porcine eye model.

Abstract

BACKGROUND: Accurate measurement of intraocular pressure (IOP) is critical in veterinary ophthalmology, yet performance differences between handheld tonometers remain a clinical challenge. This original article aims to directly evaluate the newly launched ReichertTono-Vera Vet (TVV) compared to two commonly used tonometers, the IcareTono-Vet Plus (TVP) and ReichertTono-Pen Vet (TPV), using an ex vivo porcine eye model across a wide range of IOP levels. METHODS: Ten eyes were used to compare the accuracy and consistency of TVV, TVP, and TPV across physiological (5-25 mmHg) and high (30-70 mmHg) intraocular pressure (IOP) ranges. Bias assessment, Bland-Altman plots, regression analysis, and receiver operating characteristic (ROC) analysis were conducted. RESULTS: TVV demonstrated superior accuracy in the physiological range, with a mean deviation of 1.16&#x2009;&#xb1;&#x2009;2.31 mmHg and narrow limits of agreement (min =-3.38 mmHg, max&#x2009;=&#x2009;5.69 mmHg). At higher pressures, TVV's variability increased (mean deviation&#x2009;=&#x2009;0.566&#x2009;&#xb1;&#x2009;5.95 mmHg). TVP consistently overestimated IOP, particularly at high pressures (mean deviation&#x2009;=&#x2009;5.68&#x2009;&#xb1;&#x2009;6.46 mmHg), while TPV significantly underestimated IOP (mean deviation =-11.0&#x2009;&#xb1;&#x2009;8.55 mmHg; p&#x2009;<&#x2009;0.001). Bland-Altman analysis confirmed TVV's better agreement with true IOP in the physiological range. Regression analysis showed a strong correlation for TVV (R&#xb2; > 0.90), and ROC analysis highlighted its strong discriminative ability (AUC&#x2009;=&#x2009;0.913). None of the devices effectively differentiated accurate measurements at high IOPs. CONCLUSIONS: TVV outperformed TVP and TPV in accuracy and consistency, particularly for physiological IOPs. Its reliability supports its use in routine IOP assessments, though all devices showed limitations at elevated pressures.