Measuring corneal hysteresis: threshold estimation of the waveform score from the Ocular Response Analyzer

Background

The aim of this study was to determine a threshold waveform score (WS) for the best score value (BSV) in the Ocular Response Analyzer (ORA).

Methods

Retrospective study. One hundred and thirty-three healthy adults were recruited. Measurements were done with the ORA 2.04.

Results

Two hundred and sixty-six eyes were analyzed. Mean age was 56.49?±?15.97?years. The mean waveform score of the BSV was 7.39?±?1.32. The waveform scores ranged from 2.8 to 9.7. Kolmogorov–Smirnov test for normality was significant (p?≤ 0.0001). Linear regression showed a significant positive correlation between IOPg (measured with the ORA) and IOP measured with Goldmann applanation tonometry (p?≤?0.0001), as well as significant negative correlation between the difference IOPg–IOP Goldmann and waveform score of the BSV values. Threshold estimation considering 95?% confidence interval was 7.23. Meanwhile, threshold estimation considering the difference IOPg–IOP Goldmann, for 3?mmHg, was 6.7.

Conclusions

When using the ORA device, we recommend that clinicians try to obtain several waveform score measurements of 7 or above. Waveform scores lower than 7 may render less reliable results.