Objective: To evaluate the influence of corneal thickness (CT) on the intraocular pressure (IOP) measurements, the agreement of IOP readings with I Care rebound tonometer (RBT) and Goldmann applanation tonometer (GAT), and the agreement of central and peripheral IOP values obtained by RBT.
Methods: Thirty-seven eyes of 34 patients after Descemet's stripping with automated endothelium keratoplasty (DSAEK) underwent CT measurement using anterior segment OCT (AS-OCT) followed by IOP evaluation with the GAT at corneal center and with the RBT at corneal center and at 1 mm from the limbus in the nasal and temporal directions. The mean IOP measurement by the RBT and measurement by the GAT were analysed by paired t test. Pearson correlation analysis were performed to assess the correlations between the measurement and the influence of CT on IOP values. Agreement between the tonometers was calculated using the Bland-Altman method.
Results: IOP obtained by GAT was (16.2 ± 4.7) mm Hg (1 mm Hg = 0.133 kPa), and IOP obtained from central cornea, nasal cornea and temporal cornea by RBT were (16.0 ± 5.3) mm Hg, (17.4 ± 5.0) mm Hg and (17.1 ± 5.0) mm Hg, respectively. There was no statistical difference between the IOP on central cornea obtained by GAT and RBT (t = 0.77, P = 0.446), IOP on the peripheral cornea were higher than on central cornea by RBT (t = 3.24, 3.17, P = 0.003), and they were positively correlated (r = 0.869, 0.911, P < 0.05). The IOP readings showed positive relationship to CT values. Bland-Altman scatter plots showed reasonable inter-method agreement between each technique of IOP measurements.
Conclusions: After DSAEK, the IOP readings obtained by RBT or GAT show positive relationship to CT values. There are reasonable agreements between each technique of IOP measurements. Considering the special advantages, RBT is an effective method to observe the IOP changes after DSAEK.