To evaluate the inter- and intra-observer variability of ocular response analyzer (ORA) measurements, and to evaluate the relationships among the intraocular pressures (IOPs) obtained by ORA, Goldmann applanation tonometer (GAT) and non-contact tonometer (NCT).

The present study included 45 normal eyes from 45 volunteers. Three masked observers performed ORA measurements. NCT and GAT measurements were performed by one independent observer. The reproducibility of ORA was assessed by ANOVA-based intraclass correlation coefficient (ICC) and coefficient of variation (CV). Comparison among the tonometers was performed using the Bland-Altman plot and paired t -test.

The ICC for inter-observer reproducibility of ORA parameters was 0.90 to 0.97. The corresponding CV values were 13.2% to 19.1%. The intra-observer ICC values for IOP cc were 0.78 to 0.88. CV was 11.2% to 16.8%. For CRF, ICC values were 0.80 to 0.84 with CV values as 11.6% to 15.9%. For CH, ICC values were 0.74 to 0.82 and CV values were 13.0% to 15.9%. The difference in mean IOP values between IOP cc and IOP g was statistically significant ( p = 0.04). However, no difference was found among other tonometers, and only IOP cc did not result in significant correlation with central corneal thickness (CCT) ( p = 0.38).

The intra- and inter-observer reproducibility was substantial for IOP cc, IOP g, CH and CRF, for all observers. Additionally, IOP measured with ORA did not result in significant differences from GAT and NCT.