Clinical Validation of M-TONX: A Novel Combo Rebound Tonometer and Pachymeter

This study aims to perform a clinical investigation of an innovative rebound technology-based device, the M-TONX, to simultaneously measure intraocular pressure (IOP) and central corneal thickness (CCT).

The IOP and CCT of the patients were first measured by the M-TONX. Then, the measurements were repeated by the Goldman applanation (GAT) and the Pentacam corneal topographer, as the standard devices. For the statistical analysis, the patients were stratified based on their IOPs to group 1 (IOP < = 16 millimeters of mercury [mm Hg]), group 2 (16 mm Hg < IOP < 23 mm Hg), and group 3 (IOP > = 23 mm Hg). The stratification was also performed for the CCTs as: class 1 (CCT < = 475 µm), class 2 (475 < CCT < 574 µm), and class 3 (CCT > = 575 µm).

Of the 374 eyes (225 subjects and 43% women), 262, 66, and 46 eyes belonged to group 1, group 2, and group 3, respectively. Very high IOP (>35 mm Hg) was observed in 12 eyes. The overall confidence interval of the deviation (confidence level = 95%) from the standard devices was estimated to be 0.7 to 1.2 mm Hg for IOP, and -12.7 to -5.4 µm for CCT. The stratified analysis showed substantial agreement with the standard devices with the intraclass correlation > 0.65 and the Pearson Correlation > 0.8 calculated for all the groups and classes.

The M-TONX exhibited a reliable performance concerning the standards for measuring IOP and CCT. Its accuracy remains stable for a broad range of IOP and CCT. The M-TONX successfully incorporates two separate functionalities into a single compact user-friendly device.

This study uncovers the conformity of the technology with the standards, linking fundamental research to clinical care.