Evaluation of some factors affecting the agreement between the Proview Eye Pressure Monitor and the Goldmann applanation tonometer measurements

Abstract

Background:  Our aim was to examine whether training level and ocular factors could account for part of the difference in intraocular pressure (IOP) measured using the Goldmann applanation tonometer (GAT) and Proview Eye Pressure Monitor (PPT).

Methods:  One hundred and nineteen individuals (238 eyes) were enrolled in the study. The mean age was 35.8 years (range 21 to 79). All study participants obtained IOP measurements using the PPT after hearing instructions on how to perform PPT. Glaucoma patients obtained additional IOP measurements using PPT after viewing an instructional video and after 30 days of home use. IOP was also measured using the GAT at each experimental session.

Results:  The difference in IOP measured by the GAT and the PPT was 0.55 ± 3.38-mmHg, 0.17 ± 3.79-mmHg and ‐1.30 ± 3.79-mmHg for myopic, emmetropic and hypermetropic groups, respectively, which were statistically significant (ANCOVA; p = 0.014). The difference in IOP between GAT and PPT was not significantly different for measurements obtained after verbal instructions, instructional video or after 30 days of home use (Repeated‐ANCOVA; p = 0.30). The overall agreement between the GAT and the PPT was poor. Intra‐class correlation coefficient was 0.575, and the 95% confidence interval (CI) of agreement was ‐6.93 to +6.73-mmHg.

Conclusion:  There was a small systematic difference in IOP measured by the GAT and PPT when comparing the different refraction groups; however, this level of difference between the groups is unlikely to be of clinical significance. The level of training in using the PPT did not influence its measurements. The limits of agreement between the PPT and the GAT were wide and long‐term use of PPT did not improve its agreement.

Key words:

• glaucoma
• Goldmann applanation tonometer
• intraocular pressure
• Proview phosphene tonometer

ACKNOWLEDGEMENT

We would like to thank Drs Lora D Haynes and Stephen E Edgell for statistical assistance.