Intrasubject repeatability of corneal morphology measurements obtained with a new Scheimpflug photography–based system

PurposeTo evaluate in normal healthy eyes the intrasubject repeatability of anterior and posterior corneal curvature measurements and other anatomic anterior segment measurements obtained with a new topography system combining Scheimpflug photography and Placido-disk technology.SettingVissum Corp., Alicante, Spain.DesignEvaluation of technology.MethodsAll eyes received a comprehensive ophthalmologic examination including anterior segment analysis with the Sirius system. Three consecutive measurements were performed with the device to assess the intrasubject repeatability of the following parameters: anterior and posterior corneal curvature and shape factor, white-to-white (WTW) corneal diameter, central and minimum corneal thickness, and anterior chamber depth (ACD). The within-subject standard deviation (Sw) and intraclass correlation coefficient (ICC) were calculated.ResultsThis study included 117 eyes of 117 subjects (mean age 42 years; range 7 to 80 years). For anterior and posterior corneal curvatures, the Sw was 0.04 mm or lower and the ICC was higher than 0.990. For shape-factor measurements, the Sw was below 0.08 in all cases and ICC values ranged between 0.909 and 0.994. Significantly larger Sw values were found for the anterior and posterior shape factor calculated for 8.0 mm compared with 4.5 mm (P<.01). An Sw value below 3 μm was observed for the central and minimum thickness, with ICC values close to 1. The mean Sw for ACD and WTW was below 0.1 mm.ConclusionIn healthy eyes, the new topography system provided repeatable measurements of several anterior segment parameters, including anterior and posterior curvature and pachymetry.Financial DisclosureNo author has a financial or proprietary interest in any material or method mentioned.