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

Abstract

Purpose: To compare the repeatability and reproducibility of corneal curvature measurements using the Pentacam eye scanner (Oculus Optikgeräte 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 Pentacam and −0.08±0.21 D (range: −0.50 to +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.]