Age dependency of the reduced scattering coefficient and viscoelastic character, and their relationship in Japanese female skin

Abstract

We measured the reduced scattering coefficient (µ_s') with the edge-loss method at skin sites on the faces and upper arms of Japanese females aged 20s to 50s, and observed significant negative correlations at all sites, including the mouth. At the same mouth site, we also measured the viscoelastic properties with a Cutometer MPA580 and evaluated their correlation with µ_s'. Significant correlations were observed for the parameters of pliability, the portion of the viscoelasticity during the suction phase, and total recovery from the Cutometer against µ_s' with the effect of age removed. The results experimentally suggest the relation between µ_s' and the collagen condition.

Fig. 1.

LUTs for associated (a): µ_a (mm^-1) and (b): µ_s’ (mm^-1) for given R and T. Intermediate levels are at regular intervals on a logarithmic scale.

Fig. 2.

Suction cycle of the MPA580 skin elasticity probe and output parameters related to viscoelasticity. The description of each parameter (rightmost) is according to the MPA580 brochure.

Fig. 3.

Average spectra of (a) R and (b) T for each age group and each measurement site. The results of Welch’s t-test between each pair of adjacent groups at 700 nm are displayed as *: p < 0.05; **: p < 0.01; ***: p < 0.001; NS: not significant.

Fig. 4.

Average spectra of (a) µ_a and (b) µ_s’ for each age group for each measurement site. The results of Welch’s t-test between each adjacent group at 700 nm in (b) are displayed as *: p < 0.05; **: p < 0.01; ***: p < 0.001; NS: not significant.

Fig. 5.

Plots of (a) µ_a and (b) µ_s’ at 700 nm against age for each measurement site. Correlation coefficients with significance are displayed as ***: p < 0.001; NS: not significant.

Fig. 6.

Residual plots for linear regression of (a) R0, (b) R6, (c) R8, and (d) µ_s’ at 700 nm at the side of the mouth against age.