Accuracy Of Tonometry Measurements From A Robotic Non-Contact Device

Unlike Goldmann Applanation Tonometry (GAT), which requires topical anesthetic drops and fluorescein dye, automated non-contact tonometry (NCT) uses an air puff to measure intra-ocular pressure (IOP), making it less invasive, easy to use, rapid, and more comfortable for patients. The purpose of this study is to evaluate the accuracy of measurements of IOP from a robotic NCT device, thereby facilitating measurements within pre-test rooms in high volume clinical settings. 

Data collection happened from February to April 2024, as single visit, in two sites in the United States: New View Optometric Center, La Mesa, CA and Illinois College of Optometry, Chicago, IL. This study was conducted in compliance with the ethical principles that have their origin in the Declaration of Helsinki.

This was a randomized multi-center study. Inclusion criteria were subjects older than 22 years of age and able to provide informed consent. Subjects with high corneal astigmatism (>3D), difficulty fixating, history of recent contact lens wear, diseases of the cornea, or corneas thinner than 500 µm or thicker than 600 µm were excluded. The study aimed to collect data from at least 40 subjects in each of three pressure categories: group 1 (<7 to 16 mmHg), group 2 (>16 to < 23 mmHg), and group 3 (≥ 23 mmHg). An optometrist took the IOP measurements with the TRK-3 OMNIA (Topcon Corporation, Tokyo, Japan) then performed the GAT measurement. The GAT result was compared to the final TRK-3 measurement using Bland-Altman analysis.

A total of 125 subjects were enrolled and 120 completed the study. In group 1, TRK-3 shows slightly higher mean values compared to GAT (16.6 and 14.5 mmHg, respectively). In group 2, both devices provide similar results, with mean values of 19.2 mmHg (GAT) and 19.0 mmHg (TRK-3). In group 3, GAT reports a higher mean than TRK-3 (26.7 and 24.3 mmHg, respectively). The overall mean IOP is similar between the devices (20.1 mmHg for GAT, SD 5.8 and 19.9 mmHg for TRK-3, SD 4.5). There is a non-statistically significant over-estimation with low IOPs and under-estimation with high IOPs with the TRK-3 OMNIA compared to GAT. This is a common phenomenon among various NCTs. The limits of agreement within all IOP ranges are within ±5 mmHg.

The TRK-3 OMNIA measures IOP within the accuracy limits specified by ANSI standards for tonometry. The ability to reliably capture IOP using a robotic, non-invasive, and rapid device facilitates objective measurements in routine eye exams and large-scale screening programs.