Comparison of ocular response analyzer, dynamic contour tonometer and Goldmann applanation tonometer

The aim of this study was to compare the intra-ocular pressure (IOP) obtained by ocular response analyzer (ORA), dynamic contour tonometer (DCT) and Goldmann applanation tonometer (GAT). In 102 patients (47 with primary open-angle glaucoma and 55 healthy controls) IOP was measured with GAT, ORA and DCT in one eye. The agreement between GAT, DCT and ORA values was assessed using Bland-Altman plots. The discrepancy between the methods was related to central corneal thickness (CCT), corneal hysteresis (CH) and corneal resistance factor (CRF) using linear regression models. Significant differences were observed amongst DCT, corneal compensated ORA (ORAcc) and GAT (P < 0.01). Only the ORAcc and DCT were comparable. ORAcc and DCT significantly over-estimated IOP compared to GAT and for ORAcc this difference depended on the height of IOP. A significant correlation was found between CCT and the deviation of DCT and ORAcc from corrected GAT (both P < 0.0001). Our study showed a low degree of agreement between IOP measured by ORA, DCT and GAT. DCT and ORAcc over-estimated the IOP compared to GAT.