Evaluation of Corneal Power Measured With Rotating Scheimpflug Photography and Scanning-Slit Corneal Topography

Abstract

Purpose: : To investigate the repeatability, reproducibility, and agreement in anterior, posterior, and in particular the total corneal power of two topography devices, rotating Scheimpflug photography (RSP) and scanning-slit topography (SST).

Methods: : Seventeen eyes from 17 subjects (mean 24.7 ± 4.1 years) were included in the study. The corneal shapes within the central 3.0 mm were measured with rotating Scheimpflug photography Pentacam (Oculus) and scanning-slit corneal topography Orbscan II (Bausch&Lomb). We evaluated the within-instrument repeatability and reproducibility with two raters and the overall between-instrument agreement of the measurements by using intra-class correlation coefficients (ICCs) and the Bland-Altman method.

Results: : The repeatability of both Scheimpflug photography and scanning-slit corneal topography were high, with ICCs ranging from 0.7 to 0.9. Scheimpflug photography outperformed scanning-slit corneal topography for anterior power, posterior power, and total corneal power. The reproducibility results were similar, with agreement limits consistently narrower for RSP. The between instrument agreement was moderate, with agreement limits around the average value for total corneal power of 0.46 from 0.032 to 0.889.

Conclusions: : Our results suggest that repeatability and reproducibility in Scheimpflug photography are higher than in scanning-slit topography.The agreement between rotating Scheimpflug photography and scanning-slit topography for total corneal power was moderate.

Keywords: cornea: basic science • topography • refraction