Fig. 3
Correlations between the Cer [NP]/[NS] ratio and various skin properties in the healthy female facial skin. Correlation between the Cer [NP]/[NS] ratio and the SC functional parameter, TEWL (rS= − 0.369, p < 0.01) (a). Correlation between the Cer [NP]/[NS] ratio and the skin surface roughness parameter, surface texture score (roughness and smoothness) (rS= 0.343, p < 0.01) (b). Correlation between the Cer [NP]/[NS] ratio and the skin photometric color parameters, L* value (lightness) (rS = 0.254, p < 0.01) (c) and a* value (redness) (rS = − 0.227, p < 0.01) (d). Spearman’s correlation; the correlation coefficients (rS) and p-values are shown. TEWL, transepidermal water loss; AU, arbitrary units