Skin firmness and elasticity assessment

Skin firmness and elasticity have been evaluated respectively with a clinical evaluation and a Cutometer SM575^™ (Courage-Khazaka Electronic, Köln, Germany). The firmness evaluation was scored from “Absent/Light” to “Moderate/Important” by an examiner. The cutometer measures the elasticity of the skin in vivo by a suction test. A probe of 6 mm diameter is applied to the skin and a temporary vacuum is created (400 mbars), thus deforming the skin (on time: 3 seconds; off time: 2 seconds; repetition: 5). Adhesive tape is attached to the probe and prevents the adjacent skin from being sucked into the chamber. The device holds a spring ensuring a constant application pressure (50 g/cm²). An optical system made of a light source and a receptor determines the skin deformation and its slackness. Different parameters are measured: immediate deformation Ue (U extensibility), delayed deformation Uv (U viscous), final deformation Uf (Uf = Ue + Uv), and deformation of immediate retraction Ur, when the vacuum is removed. The ratio Ur/Ue characterizes the elasticity of the skin and is independent of the thickness of the skin.18