# Agreement and Clinical Utility of the Easytone Transpalpebral Tonometer Compared with Goldmann Applanation, Tono-Pen, and Icare in Healthy Eyes

## TL;DR

This study compares four devices for measuring eye pressure in healthy people and finds that the Easytone device tends to give higher readings than others.

## Contribution

The study evaluates the clinical utility and agreement of the Easytone tonometer compared to established methods in healthy eyes.

## Key findings

- The Easytone tonometer overestimates intraocular pressure compared to Goldmann applanation.
- The Icare 200 underestimates intraocular pressure compared to other devices.
- The Tonopen AVIA shows the closest agreement to Goldmann applanation measurements.

## Abstract

Objective: To compare intraocular pressure (IOP) measurements obtained using the Easytone Transpalpebral Tonometer (ETT) with the Icare 200 (IC200), Tonopen AVIA (TPA), and Goldmann Applanation Tonometer (GAT) in healthy individuals. Methods: Fifty-eight right eyes of 58 healthy volunteers underwent IOP measurement with all four devices. Three consecutive readings were taken per device and averaged. Two masked observers performed all measurements. Agreement was assessed using intraclass correlation coefficients (ICCs) and Bland–Altman analysis, and repeated-measures ANOVA compared mean IOP values. Results: Mean IOP values were 15.18 ± 1.88 mmHg (ETT), 14.45 ± 2.24 mmHg (TPA), 13.38 ± 2.65 mmHg (IC200), and 14.33 ± 2.03 mmHg (GAT) (p < 0.001). ETT provided significantly higher values than IC200, TPA, and GAT, while IC200 underestimated IOP compared with TPA and GAT. No difference was observed between TPA and GAT. Inter-observer agreement was excellent (ICC 0.805–1.000). Agreement analysis showed weaker ICC values for ETT–TPA (0.642) and ETT–IC200 (0.615). Bland–Altman plots confirmed the closest agreement between GAT and TPA, and the poorest agreement between ETT and IC200. Conclusions: ETT tends to overestimate and IC200 to underestimate IOP compared with GAT. TPA demonstrated the closest agreement with GAT and may be the most reliable alternative in clinical practice. ETT can be useful when applanation is not feasible, but its limited agreement should be considered.