Evaluation of anti-wrinkle effects on humans

Synopsis Image analysis provides a practical method for studying the cutaneous relief and better understanding of the formation of wrinkles during ageing and their regression induced by an anti-wrinkle product. Quantimet 900 degrees allows a fully automated analysis of 40 replicas of skin surface per cycle of 6 h. The basic principle consists of measuring shadows, generated by incident lighting at the surface of Silflo replicas. Incident light of 38 degrees was selected for analysing crow's feet wrinkles and 26 degrees for the microrelief when crow's feet were absent (slight furrows less than 50 mu-m). The following parameters were recorded: the number of wrinkles, their mean depth, and the coefficient of developed skin surface (CDSS). An O/W emulsion containing 30% biological ingredients was applied daily on the face of 140 female subjects, aged from 20 to 57 years, during 4 weeks. Replicas were made before the first application (t(0)) and 24 h after the last one (t(0)). Data obtained with the image analysis method showed a decrease in number and depth of crow's feet from t(0), to t(4) of 16% and a sharp decrease of the CDSS (30%). No modification of the microrelief was observed. These results were confirmed by measuring forehead casts with the Anaglyphographc(R) apparatus (a profilometric method) on the same subjects: a decrease of 40% in number and 23% in depth were recorded for the forehead wrinkles, with no modification of the microrelief. Both image analysis and profilometry measured the effects provoked by this treatment. The CDSS, which might measure the reservoir of extensibility of the surface of the skin, should be the best parameter to demonstrate the efficiency of anti-wrinkle products.