Mapping, in vivo, the uniformity of two skin properties alongside the human face by a 3D virtual approach.

OBJECTIVE: To determine the homogeneity in the distribution of two cutaneous functions (hydration and elasticity) along the entire human face. MATERIAL AND METHODS: The half faces (right or left, randomly chosen) of two groups of Caucasian women were measured on 24 different small sites (elasticity) and 41 others (hydration), by instruments of small-sized probes (Cutometer® and Corneometer® , respectively). Hydration of the face was recorded at different times (up to 24 h), post application of a highly hydrating product. The recorded values (left and right half faces) were further gathered and digitally positioned on a virtual feminine face and their intensity was illustrated through a colored white (lower values)-blue (higher values) scale. RESULTS: The reconstitution of the mapping of the two measured parameters (from the left and right sides of different subjects), shows a perfect symmetry vis à vis the nose axis. However, both parameters present slightly variable but significant values along the human face. Sites from the temple are less elastic than chin or forehead. The upper and lower parts of the forehead show slight disparities in their elasticity values. Cheeks are significantly less prone at retaining their imparted hydration status (lost 2 h after application of a hydrating product) as compared to sub-ocular regions or chin that retain their hydration up to 24 h. Attempts to establish a mutual relationship between the two skin properties unsurprisingly failed. CONCLUSION: The two studied skin properties show a slight but highly symmetric disparity along the entire human face.

Seasonally-induced alterations of some facial signs in Caucasian women and their changes induced by a daily application of a photo-protective product.

OBJECTIVES: These were two-fold: (i) to assess the possible changes in some facial signs induced in a 6-month period by the periodical shift from winter to summer in Caucasian women and (ii) to appraise the preventive effects of a strong photo-protective product. METHODS: The facial signs of two cohorts of French women (N= 40 and 42), of comparable ages were graded between winter to summer. One group was left unprotected whereas the other daily applied a strong photo-protective product for 6 months. Facial signs (structural and pigmentation-related) were graded in blind by a panel of 12 experts from photographs taken under standard conditions. A global and focused analysis of the skin colour or dark spots, when present, was carried out through spectro-radiometry under diffuse and standardized visible light, using the L*, a*, b* referential system. RESULTS: The unprotected group showed significant changes in summer as compared to winter on 10 facial signs (two-third of the studied signs) that presented an increased severity, of variable respective amplitude. Five signs among the 10 were particularly and significantly affected by the seasonal transition, of an amplitude above the precision of the grading scale. Three of these five signs concerned structural elements (wrinkles), the two others being related to vascular disorders (redness). These season-induced alterations appear efficiently reduced in the photo-protected group. The colour of the facial skin then appears more homogeneous, less red, less dull, all criteria being quantified by the L*, a*, b* referential system. The comparison with a previous work carried out on Chinese women, through a similar protocol, shows that the photo-protective product brings, in Caucasian women, a more important effect upon structural and vascular features than upon pigmentation disorders, inversely to the results previously observed in Chinese women. CONCLUSION: The alterations in some facial signs occurring in a 6-month period between winter and summer are confirmed in Caucasian women, mostly related to structural (wrinkles) and vascular elements. Such changes appear alleviated or prevented by daily applications of a strong sun photo-protective product.