Reliability of Intraocular Pressure Using the Ocular Response Analyzer G3 in Eyes with Ocular Hypertension

Abstract

Purpose : The increase in intraocular pressure (IOP) is the main risk factor for glaucoma to both develop and progress. IOP reduction for whatever approach has been shown to delay or stop the progression of the disease. Therefore, IOP measurement is a crucial clinical maneuver to evaluate glaucoma patients and glaucoma suspects. The ocular response analyzer (ORA) is a method to assess IOP and some biomechanical properties of the cornea. The repeatability of this method has been demonstrated in its previous versions, but not for the generation 3 (G3) one. The objective of this study is to investigate the reliability ORA G3 in eyes with high intraocular pressure.

Methods : This cross-sectional study to assess the reliability of IOP included 26 non-consecutive patients diagnosed either with glaucoma or ocular hypertension with IOPs at the moment of the study of at least 21 mm Hg. Three consecutive measurements were made, with an interval of 1 to 2 minutes between each measurement to restart the equipment, all of them by the same operator. In all subjects, central corneal thickness (CCT) was measured with the Cirrus 6000 optical coherence tomography (OCT). The statistical package SPSS version 25 was used to analyze the intraobserver reliability with the intraclass correlation coefficient (ICC) test, as well as the Pearson test to evaluate the correlation of the variation with the central corneal thickness (CCT).

Results : Forty four eyes of 26 patients were analyzed (13 female, 13 male). The mean age was 61.3 ± 17.2 years. The most frequent diagnosis was primary open-angle glaucoma (50%), followed by glaucoma suspicion (36.3%). In regards of the reliability analysis an excellent intraclass correlation coefficient was demonstrated in all values of ORA G3, corneal compensated IOP (IOPcc), corneal hysteresis (CH), Goldmann correlated IOP (IOPg), and Waveform score (WS) (r = 0.98 p = 0.0005, r = 0.93 p = 0.0005, r = 0.97 p = 0.0005 and r = 0.77 p = 0.0005, respectively). The mean CCT was 532 ± 39 µm and there was a very weak, non-significant correlation between CCT and the level of variation of IOPcc (r = -0.04, p = 0.7) or in with IOPg (r = 0.01 p = 0.9).

Conclusions : This study demonstrates that performing IOP measurements using ORA G3 in patients with ocular hypertension has excellent reliability, making it a very good method to assess the IOP.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.