Repeatability, Reproducibility, and Agreement Between Three Different Scheimpflug Systems in Measuring Corneal and Anterior Segment Biometry

Purpose: To assess the reliability of three different Scheimpflug systems and their agreement.

Methods: Eighty-four eyes of 42 patients were examined with three Scheimpflug devices: the Galilei G2 Dual Scheimpflug Analyzer (Ziemer Ophthalmic Systems AG, Port, Switzerland), Pentacam HR system (Oculus Optikgerate GmbH, Wetzlar, Germany), and Sirius 3D imaging system (Costruzione Strumenti Oftalmici, Florence, Italy). The central corneal thickness, maximum anterior and posterior corneal elevation, anterior radius of curvature, total higher-order aberrations, and anterior chamber depth were evaluated. Repeatability and re-producibility were evaluated using coefficients of variation and intraclass correlation coefficients. Interdevice agreement was assessed by Bland-Altman comparison analysis.

Results: The three Scheimpflug systems had excellent repeatability for central corneal thickness, anterior radius of curvature, and anterior chamber depth (coefficients of variation being less than 1%). Repeatability for anterior and posterior corneal evaluation was good for the Pentacam HR and Galilei G2 (coefficients of variation < 10%) and excellent for the Sirius 3D (coefficients of variation = 0). Reproducibility was excellent in the three devices, (intraclass correlation coefficient of more than 0.9). Interdevice agreement was excellent (P > .05) for anterior radius of curvature, central corneal thickness, and anterior chamber depth, but was poor (P < .05) for corneal elevation and higher-order aberrations.

Conclusions: Reliability was good to excellent in the three devices for all measured variables. Interdevice agreement analysis suggests that measurements for anterior radius of curvature, central corneal thickness, and anterior chamber depth, but not for maximum anterior and posterior corneal elevation and total higher-order aberrations, from the Sirius 3D and Galilei G2 can be interchangeable with the Pentacam HR.