Abstract
OBJECTIVE: To study the correlation and effect of sequential measurement of intraocular pressure (IOP) with Goldmann applanation tonometer (GAT), ocular response analyzer (ORA), dynamic contour tonometer (DCT), and Corvis ST. SETTING AND DESIGN: Observational cross-sectional series from the comprehensive clinic of a tertiary eye care center seen during December 2012. METHODS: One hundred and twenty-five study eyes of 125 patients with normal IOP and biomechanical properties underwent IOP measurement on GAT, DCT, ORA, and Corvis ST; in four different sequences. Patients with high refractive errors, recent surgeries, glaucoma, and corneal disorders were excluded so as to rule out patients with evident altered corneal biomechanics. STATISTICAL ANALYSIS: Linear regression and Bland-Altman using MedCalc software. RESULTS: Multivariate analysis of variance with repeated measures showed no influence of sequence of device use on IOP (P = 0.85). Linear regression r2 between GAT and Corvis ST, Corvis ST and Goldmann-correlated IOP (IOPg), and DCT and Corvis ST were 0.37 (P = 0.675), 0.63 (P = 0.607), and 0.19 (P = 0.708), respectively. The Bland-Altman agreement of Corvis ST with GAT, corneal compensated IOP, and IOPg was 2 mmHg (-5.0 to + 10.3), -0.5 mmHg (-8.1 to 7.1), and 0.5 mmHg (-6.2 to 7.1), respectively. Intraclass correlation coefficient for repeatability ranged from 0.81 to 0.96. CONCLUSIONS: Correlation between Corvis ST and ORA was found to be good and not so with GAT. However, agreement between the devices was statistically insignificant, and no influence of sequence was observed.