Self-tonometry with the Ocuton S: evaluation of accuracy in glaucoma patients

Abstract

Background: To compare two methods of measuring intraocular pressure (IOP) and to evaluate whether repeated measurements taken with the Ocuton S applanation self-tonometer can improve reliability.

Methods: Ocuton S and Goldmann applanation tonometry (GAT), and corneal thickness measurements taken with the Orbscan topography system, were successfully performed in 64 of 68 glaucoma patients.

Results: The median IOPs were 15.5 mmHg using GAT, and 16 mmHg using the first self-taken Ocuton S measurement (n = 64). The differences between the median of the GAT measurements and the first Ocuton S measurement, and the medians of the three and six separate Ocuton S measurements were within 3 mmHg in 52%, 59% and 67% of cases, respectively. The mean corneal thickness of all evaluated eyes was 545.3 microm. There was no effect of corneal thickness on the accuracy of either of the two devices (p > 0.05).

Conclusion: Repeated measurements can improve the reliability of the Ocuton S. However, even with repeated measurements only every second patient succeeds in obtaining reliable measurements.