The evaluation of tonometry and self-tonometry with Ocuton tonometers.

Background: The purpose of the present study was to evaluate the clinical applicability of the Ocuton-A and Ocuton-S applanation tonometers, and to compare their use and accuracy parameters to those of Goldmann applanation tonometry (GAT).

Material/methods: In the first study, intraocular pressure (IOP) was measured with an Ocuton-A tonometer, followed by another measurement using GAT in 15 subjects (30 eyes). Ocuton-tonometry was performed on three occasions separated by three-minute intervals. In Study 2 the impact of increased patient familiarity on measurement accuracy using the self-tonometer was investigated in 5 subjects (10 eyes) by comparing two consecutive series of five Ocuton-S measurements. In Study 3 nine trained volunteers measured their own IOP with an Ocuton-S self-tonometer after GAT and Ocuton-A measurements by an experienced investigator.

Results: Study 1 showed that the measured IOP value was significantly higher using the Ocuton-A tonometer, compared to values obtained using GAT. In Study 2 we found that increased practice in self-tonometry did not alter measurement accuracy. In Study 3 the difference between IOP readings obtained with the Ocuton-S and Ocuton-A instruments was not significant.

Conclusions: The portable Ocuton-A tonometer may become a useful instrument for IOP measurement by professional workers outside the clinic. Qualified patients are able to use the Ocuton-S self-tonometer reliably even after limited training, and its measurement accuracy is acceptable for IOP monitoring. Both the Ocuton A and S devices consistently overestimate the IOP by approximately 2 mm Hg compared to the corresponding Goldmann readings.