A novel Hartman Shack-based topography system: repeatability and agreement for corneal power with Scheimpflug+Placido topographer and rotating prism auto-keratorefractor

The purpose of this study is to analyze the repeatability and agreement of corneal power using a new Hartman type topographer in comparison to Scheimpflug+Placido and autorefractor devices. In this cross sectional, observational study performed at the cornea services of a specialty hospital, 100 normal eyes (100 consecutive candidates) without any previous ocular surgery or morbidity except refractive error were evaluated. All candidates underwent three measurements each on a Full gradient, Hartman type topographer (FG) (iDesign, AMO), Scheimpflug+Placido topographer (SP) (Sirius, CSO) and rotating prism auto-keratorefractor (AR) (KR1, Nidek). The parameters assessed were flat keratometry (K1), steep keratometry (K2), steep axis (K2 axis), mean K , J 0 and J 45 . Intra-device repeatability and inter-device agreement were evaluated. On repeatability analysis, the intra-device means were not significantly different (ANOVA, p > 0.05). Intraclass correlations (ICC) were >0.98 except for J 0 and J 45 . In terms of intra-measurement standard deviation (Sw), the SP and FG groups fared better than AR group ( p 0.05, R 2 0.05). ICC ranged from 0.92 to 0.99 ( p