Reliability of Measurements Using Ocular Response Analyzer as a Screening Tonometer and Corneal Hysteresis Values in the Presence or Absence of Glaucomatous Changes in Fundus

Precis: Use of the Ocular Response Analyzer (ORA) as a screening tonometer in clinical practice yielded reliable measurements in over 80% of eyes screened. Including corneal hysteresis (CH) data in screening may improve the accuracy of glaucoma detection. Purpose: To examine measurement reliability when the ORA is used as a screening tonometer, and to compare CH measurements in eyes with and those without glaucomatous changes in the fundus. Patients and Methods: 1488 eyes of 747 patients (mean age: 53.5 +/- 20.4 y, range: 6-94 y) underwent intraocular pressure (IOP) measurement using ORA as screening. The percentage of eyes with a waveform score >= 6, the recommended threshold indicating reliability, was calculated. Eyes that had waveform score >= 6 and had undergone fundus photography and optical coherence tomography were assessed for the presence or absence of glaucomatous changes in fundus from optical coherence tomography and fundus images, and CH was compared between the 2 groups. Results: Mean +/- SD (range) of ORA measurements were: Goldmann-correlated IOP 14.9 +/- 4.8 (1.0-63.2) mm Hg, corneal-compensated IOP 16.2 +/- 4.7 (3.2-73.6) mm Hg, CH 9.7 +/- 1.5 (0.0-20.6) mm Hg, and waveform score 7.3 +/- 1.5 (0.1-9.7). Eighty-four percent of eyes had a waveform score >= 6. Among 192 eyes (127 patients, aged 53.5 +/- 18.0 y) with waveform score >= 6 and evaluable for glaucomatous changes in the fundus, 53 eyes were determined as positive and 139 eyes as negative. CH was 9.6 +/- 1.4 (6.8-13.3) mm Hg in the positive group and 10.2 +/- 1.2 (6.9-13.3) mm Hg in the negative group, and was significantly lower in the positive group (P=0.003). Conclusion: When using ORA as a screening tonometer, reliable results were obtained in similar to 80% of the eyes. CH was lower in the glaucomatous change-positive group compared with the glaucomatous change-negative group, but the ranges overlapped between the 2 groups.