Association between Rates of Visual Field Progression and Intraocular Pressure Measurements Obtained by Different Tonometers.

ABSTRACT

PURPOSE: To investigate the associations between intraocular pressure (IOP) measurements obtained by different tonometric methods and rates of visual field loss in a cohort of patients with glaucoma followed over time. DESIGN: Prospective, observational cohort study. PARTICIPANTS: This study included 213 eyes of 125 glaucomatous patients who were followed for an average of 2.4±0.6 years. METHODS: At each visit, IOP measurements were obtained using Goldmann applanation tonometry (GAT), the Ocular Response Analyzer (ORA) (Reichert, Inc., Depew, NY), corneal-compensated IOP (IOPcc), and the ICare Rebound Tonometer (RBT) (Tiolat, Oy, Helsinki, Finland). Rates of visual field loss were assessed by standard automated perimetry (SAP) mean deviation (MD). Linear mixed models were used to investigate the relationship between mean IOP by each tonometer and rates of visual field loss over time, while adjusting for age, race, central corneal thickness, and corneal hysteresis. MAIN OUTCOME MEASURES: Strength of associations (R2) between IOP measurements from each tonometer and rates of SAP MD change over time. RESULTS: Average values for mean IOP over time measured by GAT, ORA, and RBT were 14.4±3.3, 15.2±4.2, and 13.4±4.2 mmHg, respectively. Mean IOPcc had the strongest relationship with SAP MD loss over time (R2 = 24.5%) and was significantly different from the models using mean GAT IOP (R2 = 11.1%; 95% confidence interval [CI] of the difference, 6.6-19.6) and mean RBT IOP (R2= 5.8%; 95% CI of the difference, 11.1-25.0). CONCLUSIONS: Mean ORA IOPcc was more predictive of rates of visual field loss than mean IOP obtained by GAT or RBT. By correcting for corneal-induced artifacts, IOPcc measurements may present significant advantages for predicting clinically relevant outcomes in patients with glaucoma.