Repeatability and Reproducibility of Measurements Using a NT-530P Noncontact Tono/Pachymeter and Correlation of Central Corneal Thickness with Intraocular Pressure

Purpose. To investigate the repeatability and reproducibility of intraocular pressure (IOP) and central corneal thickness (CCT) measurements using a noncontact tono/pachymeter (NT-530P) and to assess the correlation of CCT with IOP. Methods. Forty-six eyes of healthy volunteersweremeasured by two examiners. Three consecutivemeasurements per eyewere performed. Repeatability was assessed using the coefficient of variation, and reproducibility was assessed using Bland-Altman plots. Linear correlations were used to determine agreement between CCT and noncorrected IOP and CCT and corrected IOP, which was calculated using a formula built into the NT-530P. Results. The coefficient of variation for IOP was 6.4% and for CCT was 0.4%. The 95% limits of agreement between examiners were -0.17 +/- 1.42 mmHg (range: -2.95 to 2.61mmHg) for IOP, -0.93 +/- 4.37.. m (range: -9.50 to 7.64.. m) for CCT. The corrected IOP was significantly higher than the noncorrected IOP (p= 0.010.3). The noncorrected IOP significantly correlated with CCT (r= -0.4883,.. = 0.0006). The corrected IOP showed no significant correlation with CCT (r= -0.0285, p= 0.8509). Conclusions. NT-530P offered repeatability and reproducibility in both IOP and CCT measurements. The corrected IOP calculated using the NT-530P was independent of the CCT, suggesting that this IOP may be less influenced by the central corneal thickness.