Abstract
Purpose: :
The non-contact Reichert Ocular Response Analyser (ORA) avoids several of the limitations of Goldmann applanation tonometry (GAT), which is the current clinical gold standard for intraocular presssure (IOP) measurement. We sought to compare agreement of IOP measurements using GAT and Goldmann correlated intraocular pressure (IOPg) generated by ORA.
Methods: :
260 consecutive patients presenting for glaucoma evaluation underwent ORA assessment followed by examination including GAT by an ophthalmologist masked to IOPg. For each ORA assessment, measurements were taken until a waveform score (WS) of 6.5 was obtained or until 5 measurements were obtained per eye. The relationship between GAT and IOPg and the influence of the WS upon this relationship was evaluated using linear regression. A Bland-Altman plot was used to determine agreement between GAT and IOPg.
Results: :
518 eyes of 260 patients were included. Increasing WS was found to predict a smaller difference between GAT and IOPg (β=-0.160, p≤0.001). Selecting the highest WS among ORA assessments of each eye, WS continued to predict concordance between GAT and IOPg (β=-0.158, p≤0.01). Regression analysis revealed that an increase in WS from 0 to 10 predicts a decrease in variance between GAT and IOPg of only 1.6 mm Hg. The mean IOP difference between methods was 0.115 mm Hg, which was found to be a statistically insignificant difference (p=0.391). 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. IOPg and GAT were strongly correlated (r=0.825, p≤0.001); this correlation remained strong when controlling for the following covariates: patient age, CCT, corneal hysteresis, and MD (r=0.765, p≤0.001) . A Bland-Altman plot showed limits of agreement between -5.989 and 6.219 mm Hg.
Conclusions: :
In this clinical study of patients under evaluation for glaucoma, IOPg is highly correlated with GAT. While 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 the quality of an IOPg measurement.
Keywords: intraocular pressure