Repeatability and Reproducibility of Corneal Curvature Measurements Using the Pentacam and Keratron Topography Systems

PURPOSE: To compare the repeatability and reproducibility of corneal curvature measurements using the Pentacam eye scanner (Oculus Optikgerate GmbH) and Keratron corneal topographer (Optikon 2000 SpA). METHODS: Axial topography maps were used to acquire measurements. Twenty-six eyes of 26 healthy patients were measured to determine repeatability and reproducibility. Another 10 eyes of 10 healthy patients were included in a parallel study. Three measurements per eye were performed. Repeatability was assessed via the coefficient of variation. Reproducibility was assessed using Bland-Altman plots. Linear correlations were used to determine the agreement between devices. A P value <.05 was considered statistically significant. RESULTS: The majority of coefficient of variations for both devices were within 1%. The coefficient of variation of the Pentacam was higher in the superior cornea (P<.01). The mean difference (95% limits of agreement) in the flattest meridian between examiners was -0.03 +/- 0.27 diopters (D) (range: -0.56 to +0.49 D) for the and -0.80 +/- 0.21D (range: -0.50 +/- 0.33 D) for the Keratron. The mean difference (95% limits of agreement) in the steepest meridian was -0.10 +/- 0.26 D (range: -0.60 to +0.41 D) for the Pentacam and -0.11 +/- 0.22 D (range: -0.53 to +0.31 D) for the Keratron. The mean axial power for the central 3.0 mm of the Pentacam was statistically significantly lower than that of the Keratron (P<.01). CONCLUSIONS: Although statistically significant differences were noted, both devices provided repeatable and reproducible corneal measurements centrally. Pentacam repeatability outcomes indicate that superior corneal measurements should be interpreted with caution. [J Refract Surg. 2009;25:539-544.] doi:10.3928/1081597X-20090512-08