Scheimpflug–Placido topographer and optical low-coherence reflectometry biometer: Repeatability and agreement

PurposeTo assess the repeatability of common measurements with the Sirius Scheimpflug–Placido topographer and Lenstar LS900 optical low-coherence reflectometry (OLCR) biometer and the limits of agreement (LoA) between the devices.SettingEye Hospital of Wenzhou Medical College, Wenzhou, China.DesignComparative evaluation of a diagnostic test or technology.MethodsOne randomly healthy eye of subjects was scanned 3 times with both devices. The parameters assessed were central corneal thickness (CCT), anterior chamber depth (ACD) from the corneal epithelium and from the endothelium, mean keratometry (K), and white-to-white (WTW) corneal diameter. The repeatability of scans was calculated using the within-subject standard deviation after 1-way analysis of variance was performed. The agreement between devices was assessed using the Bland-Altman LoA method, which equals the mean difference between devices ± 1.96 × standard deviation of the differences. The mean of 3 scans of each device was used to assess the LoA.ResultsForty subjects were evaluated. The repeatability of the Scheimpflug–Placido topographer and OLCR biometer was 3.10 μm and 3.32 μm for CCT, 0.04 mm and 0.05 mm for WTW corneal diameter, and 0.17 D and 0.10 D for mean K, respectively. The repeatability for both devices was 0.02 mm for the ACD from the corneal epithelium and the ACD from the corneal endothelium. On Bland-Altman LoA analysis, all parameters were within clinically acceptable limits.ConclusionBoth devices had excellent repeatability for all parameters assessed. Good LoAs were found between the 2 devices, indicating they can be used interchangeably for the parameters assessed.Financial DisclosureNo author has a financial or proprietary interest in any material or method mentioned.