Evaluation of agreement between intraocular pressure measurements using Goldmann applanation tonometry and Goldmann correlated intraocular pressure by Reichert's ocular response analyser

Abstract

Purpose: To compare agreement of intraocular pressure (IOP) measurements using Goldmann applanation tonometry (GAT) and Goldmann correlated intraocular pressure generated (IOPg) by the Reichert ocular response analyser (ORA).

Methods: Consecutive patients presenting for glaucoma evaluation underwent ORA assessment followed by examination including GAT. For each ORA assessment, measurements were taken until a waveform score (WS) of 6.5 was obtained or until five measurements were obtained per eye. The relationship between GAT and IOPg and the influence of the WS upon this relationship was evaluated. A Bland-Altman plot and linear regression were used to determine agreement between GAT and IOPg.

Results: A total of 518 eyes of 260 patients were included in the final analysis. Increasing WS was found to predict a smaller difference between GAT and IOPg (β=-0.2, P≤0.001). Selecting the highest WS among ORA assessments of each eye, WS continued to predict concordance between GAT and IOPg (β=-0.2, P=0.006). The mean IOP difference between methods was 0.1 mm Hg (±0.3), which was found to be statistically insignificant (P=0.391). This relationship between GAT and IOPg was successfully validated using a second distinct data set of 100 eyes. GAT and IOPg measurements varied by 2 mm Hg or less in 53.9% of eyes and 5 mm Hg or less in 92.3% of eyes.

Conclusion: In clinical practice IOPg is strongly related to GAT. Although higher WS is indicative of greater IOPg/GAT concordance, its influence is minimal. This study does not support the use of a specific WS cutoff to determine quality of an IOPg measurement.