Validation of Automated Fixed Force Applanation Tonometry.

Authors

Joanne C Wen, Rohan Vora, Hongyi Jiang, Stuart McKinnon, Kelly W Muir, Stacy L Tantum

Published in

Ophthalmology science. Volume 6. Issue 10. Pages 101370. Epub Aug 17, 2026.

Abstract

To validate fixed force applanation tonometry against traditional Goldmann applanation tonometry (GAT) and compare interuser reproducibility.
Prospective cross-sectional pilot study.
Patients presenting for their routine eye care at an academic glaucoma practice.
A prototype adaptor containing a camera was attached to the Goldmann tonometer of a standard slitlamp microscope set to a fixed force in conjunction with a custom tonometer tip. Recorded applanation mires were converted to an intraocular pressure (IOP) using the Imbert-Fick formula. Standard GAT was also performed. Clinical GAT, research GAT, and prototype IOP measurements among different users were also completed.
Goldmann applanation tonometry and prototype IOPs were compared in a pilot validation study, and interuser reproducibility was assessed using the 2 devices.
In the validation study, 100 eyes from 50 subjects were included. The mean difference between the prototype and standard GAT measurements was +1.0 mmHg, with 95% limits of agreement (LoA) of -3.4 to 5.5 mmHg. The mean absolute difference (± standard deviation) between the prototype IOP and the standard GAT measurement was 1.9 ± 1.5 mmHg. In the reproducibility study, 42 eyes from 21 subjects were included. The mean difference between the research technician prototype IOP and the ophthalmologist prototype IOP measurements was 0.01 mmHg with LoA of -2.5 to 2.4 mmHg. The mean absolute difference between users was significantly lower when using the prototype compared with standard GAT (0.9 ± 1.2 mmHg vs. 1.6 ± 1.1 mmHg, P = 0.003).
Preliminary measurements using a fixed force applanation tonometry method demonstrated comparable results with standard GAT with improved interuser reproducibility.
The authors have no proprietary or commercial interest in any materials discussed in this article.

PMID:
42763533
Bibliographic data and abstract were imported from PubMed on 20 Sep 2026.

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