Comparison of Intraocular Pressure Measurements Obtained by Icare PRO Rebound Tonometer, Tomey FT-1000 Noncontact Tonometer, and Goldmann Applanation Tonometer in Healthy Subjects.

Abstract

To compare intraocular pressure (IOP) measurements obtained by Icare PRO rebound tonometer (RT), Tomey FT-1000 noncontact tonometer (NCT), and Goldmann applanation tonometer (GAT) in healthy subjects, and to investigate the influence of central corneal thickness (CCT) on IOP measurements. A total of 132 eyes of 66 healthy subjects were included in the study. All IOP measurements were applied in a sitting position and always in the same order (RT, NCT, and GAT). CCT was measured by noncontact anterior segment optical coherence tomography. The mean CCT was 523.5±31.2 μm. The mean IOPs with GAT, NCT, and RT measurements were 14.56±2.77, 13.42±2.99, 14.18±2.55 mm Hg, respectively. A significantly good agreement was found between RT and GAT measurements (P=0.515). The mean difference between RT and GAT measurements was -0.38 mm Hg. An underestimation was found in NCT measurements compared with GAT ones as defined from paired comparisons (P=0.003). The mean difference between NCT and GAT measurements was -1.14 mm Hg. There was no significant difference between NCT and RT readings (P=0.069). The mean difference between NCT and RT measurements was -0.76 mm Hg. There was a significant correlation between GAT-NCT (r=0.740, P<0.001), GAT-RT (r=0.743, P<0.001), NCT-RT (r=0.729, P<0.001) measurement methods. The increment in measured IOP for a 10 μm increase in CCT was 0.16, 0.33, and 0.18 mm Hg for the GAT, NCT, and RT, respectively. The IOP readings with the new Icare PRO RT showed good correlation with those obtained by GAT. Tomey FT-1000 NCT underestimated the IOP compared with GAT.