274 .§. tn 185000 165000 145000 125000 105000 85000 65000 45000 25000 5000 a 5 JOURNAL OF COSMETIC SCIENCE 10 15 20 shear rate (s- 1 ) 25 _..,__ upper curve at opening - - ♦ - · back curve at opening --+--upper curve after 1 day - - •- - · back curve after 1 day -upper curve after 3 days - - •- - · back CU1Ve after 3 days --+--upper cL1Ve after 7 days - - + - · back curve after 7 days ---e--upper curve after 1 O days - - 0- - · back CLD'Ve after 1 0 days Figure 13. Flux rheograms of RETI C concentrate emulsion after storage at 25°C. Table II Conductivity of RETI C and RETI C Concentrate Emulsions After Storage at 25°C Days of storage RETI C RETI C concentrate 1 1.06 mS 1.00 mS 3 0.96mS 0.55 mS 7 0.98 mS 0.51 mS 10 0.71 mS 0.46 mS (a) (b) Figure 14. Microphotographs (1250 x) of RETI C emulsion at opening (a) and after storage at 40 ° C for 10 days (b).

ANTI-AGING EFFECTIVENESS OF RETINOL EMULSIONS 275 (a) (b) Figure 15. Microphotographs ( 12 5 0 x) of RETI C concentrate emulsion at opening (a) and after storage at 40 ° C for 10 days (b). IN VIVO TEST The effectiveness of the emulsions employed in the anti-aging treatment was demon­ strated by evaluating the visible results on the skin surface. As an example, we report a few images corresponding to the face skin of a volunteer, before and after the treatment. These images have been selected because they are the sharpest and most representative ones. The selection derived from a wary examination of the results in vivo. It can be assumed that for all ten panelists subjected to the in vivo test, the products studied were able to reduce the wrinkles so that the results are very similar. In Figure 16 the images of forehead skin of the volunteer woman before (Figure 16a) and after (Figure 166) treatment with RETI C emulsion for eight weeks are reported. The cream gives a notable reduction of the lion wrinkle (the forehead-nose junction between the eyebrows) depth. Figure 17 shows the nose-mental wrinkle (the junction between the nose and the mouth's corner) before (Figure 17a) and after (Figure 176) treatment with RETI C concentrate emulsion. Also, in this case, the studied product is able to reduce the wrinkles, making them less deep and visible. (a) (b) Figure 16. Microphotographs of the skin surface before (a) and after (b) anti-aging treatment with RETI C emulsion for 8 weeks. In the images the lion wrinkle is visible.