The Interday Repeatability of Parameters for the Assessment of Progressive Disease in Subjects With Less Advanced Keratoconus

•Obtaining measurements by the Pentacam HR over time increases variation in measurements. The assessment of interday repeatability is thus importance understanding at which change magnitude a true progression can be suspected.•The Kmax depends on disease and must considered.•The use single, or mean several, when estimating affects common auto-keratometer could helpful assessing more advanced equipment not available. PurposeTo evaluate measurement parameters used for detection keratoconus prediction limits (PL) single measurements, coefficient (RC) replicate measurements.DesignProspective reliability analysis cases control eyes.MethodsTwenty-five eyes 25 subjects with KC healthy controls were included. Four consecutive made, 3 days apart, tomographic instrument (denoted Pentacam) Nidek ARK 560-A keratometer). Main outcome measures intra- RC keratoconus.ResultsThe most repeatable parameter obtained was curvature power central flat meridian (K1, 0.44 D [RC], -0.55 to 0.60 diopter [D] [PL]), followed steep (K2, 0.72 -0.90 0.94 [PL]). K1 K2 similar using keratometer 0.32 -0.66 0.57 [PL], K2, 0.93 -1.36 1.08 steepest point (Kmax, 0.84 1.11 [PL]) would benefit from being stratified: = PL -0.49 0.67 < 49.0 D, -1.19 1.42 ? D.ConclusionsThe replicate, should considered diagnosing progressive disease. exhibited best intraday repeatability. benefits stratified according severity. To Prospective eyes. Twenty-five keratoconus. D.