Skin microrelief topography measurements of ageing skin using a light transmission method

Anti-wrinkle creams, anti-ageing products and allkinds of skin care products, developed to affectskin relief and reduce lines and wrinkles, are verypopular and good sellers. Also for these products,it is necessary to comply with the actual cosmeticEU legislation and to substantiate the claims made.The recently developed Skin Visiometer basedon light transmission through blue coloured sili-cone replicas, can be used to study skin micro-relief. In the present experimental study, thequestion is answered whether this method is ascientifically acceptable technology to study skintopography and whether it can be used in theassessment of micro relief properties of dermato-cosmetic properties.Calibrated metal plates, displaying lines withdepths between 6 and 361 mm, were used to deter-mine the accuracy, sensitivity and reproducibilityof the technique as well as the parameters of im-portance during measurement. The precision ofthe measurements was particularly good between10 and 361 mm. The sensitivity of the method wasbetween 10 and 20 mm.Replicas of volar forearm skin were takenfrom six groups (n  15) of male and female vol-unteers in the age ranges of 20 to 35, 35 to 45, 45 to55 and 55 to 65 years. In addition to the instrumen-tal roughness parameters (Rz, Rt, Rm and Ra), thesurface of the furrows, the number of primary andsecondary lines and the number of intersectionswere determined. For both sexes, significantlylower values were observed for Rz, Rm and Rt in the younger age group than in the older agegroup. In addition, the numbers of primary andsecondary lines and the number of intersectionswere higher, pointing to a more structured micro-relief in younger forearm skin.Diurnal rhythm, the relative humidity of themeasuring room and the position of the forearmwere found to be significant factors, while roomtemperature and pre-cleansing of the skin withmild products were not.Following the application of a hydrating cream(twice daily for 14 days) to the forearm skin of theolder female age group, the Rz, Rt, Rm and Radecreased, while the other parameters measured,except for the surface taken in by the lines, in-creased indicating that the microrelief was modi-fied towards the typical pattern observed inyoung skin.