Evaluation of the intraocular pressure measured with the ocular response analyzer

Comparison of the magnitude and repeatability of the intraocular pressure (IOP) measured with the Ocular Response Analyzer (ORA) to that measured with the Goldmann tonometer.

Two sets of IOP measurements were made, for 89 eyes of eighty-nine subjects, approximately 1-week apart. Goldmann tonometry was performed subsequent to non-contact tonometry, in which the order of measurement was randomized between the ORA and the Topcon CT80 non-contact tonometer (CT80). Each method was assessed twice for intrasession repeatability. The limits of agreement between each non-contact pressure and that measured with the Goldmann tonometer were assessed once per session. The level of statistical significance was 0.05.

The mean differences between the ORA-corneal compensated, Goldmann-correlated, and CT80-IOP (ORA-IOPcc; ORA-IOPg and CT80-IOP) versus the Goldmann IOP were -0.3 +/- 2.7 mmHg (mean +/- SD), -0.3 +/- 2.2 mmHg and -0.3 +/- 2.1 mmHg, respectively for session 1 and 0.3 +/- 3.0 mmHg, 0.2 +/- 2.2 mmHg, and -0.5 +/- 2.2 mmHg, respectively, for session 2. The repeatability coefficients were +/- 5.3 mmHg, +/- 4.2 mmHg, +/- 2.5 mmHg, and +/- 1.9 mmHg, respectively for ORA-IOPcc, ORA-IOPg, CT80-IOP, and Goldmann IOP in session 1 and +/- 3.8 mmHg, +/- 3.6 mmHg, +/- 1.6 mmHg, and +/- 1.9 mmHg, respectively for session 2.

The repeatability indices for the ORA were poorer than those with the Goldmann tonometer and the CT80 in both sessions. However, the average IOP measured with the ORA did not vary significantly from those measured with the other two tonometers in either session. The ORA provides valid, repeatable measures of IOP.