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pubblicata il 28.09.2012

Chen, Wuhe, et al. "Scheimpflug–Placido topographer and optical low-coherence reflectometry biometer: Repeatability and agreement." Journal of Cataract & Refractive Surgery 38.9 (2012): 1626-1632.

Author information: School of Optometry and Ophthalmology and Eye Hospital, Wenzhou Medical College, Wenzhou, Zhejiang, China.


To 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.


Eye Hospital of Wenzhou Medical College, Wenzhou, China.


Comparative evaluation of a diagnostic test or technology.


One 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.


Forty 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.


Both 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.

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