RESUMO
PURPOSE: The aim of this study was to provide normative databases of Fourier analysis (FA) and Belin-Ambrósio enhanced ectasia display (BAD) in healthy White 4-year-old emmetropic children. METHODS: FA parameters analyzed were spherical component (SRmin), spherical eccentricity (SEcc), maximal decentration (MD), regular astigmatism at the center (Astigm. C) and periphery (Astigm. P), and irregularity (I). The parameters obtained by BAD included summary indicator BAD D, anterior corneal curvature (K1 and K2, D), maximal keratometry (Kmax, D), maximal Ambrósio relational thinnest (ART max), and pachymetric and BAD indices. RESULTS: Eighty-nine eyes of eighty-nine 4-year-old children were included. The mean values of FA parameters were the following: SRmin 7.77, SEcc 0.600, MD 0.160, Astigm. C 0.070, Astigm. P 0.050, and I 0.019. The mean K1 and K2 in our study group were 42.92 ± 1.29 D and 43.75 ± 1.41 D, with the mean BAD D value 0.42 ± 0.67. The mean PPI min 0.629 ± 0.117, PPI max 1.059 ± 0.155, PPI avg 0.847 ± 0.103, Kmax 44.10 ± 1.39, and median of ART max 515.0 were recorded. No statistically significant differences between male and female sex in any of FA or BAD parameters were found. CONCLUSIONS: This is the first study providing large normative data on FA and BAD in 4-year-old White emmetropic children. We proposed a cutoff D value for early ectasia and clinical keratoconus in 4-year-old children.