Abstract
BACKGROUND: Sagging of facial skin is a critical factor associated with an aged appearance. However, the mechanism of sagging has not been fully elucidated. The facial skin contains vellus hair (fine hair), but the contribution of vellus hair to skin condition and facial aging has yet to be studied. AIM: We aimed to clarify the influence of vellus hair on the physical properties and sagging severity of facial skin by establishing an evaluation system for vellus hair condition. METHOD: Photographs were taken to assess the vellus hair condition in the cheek area in 30 middle-aged female volunteers. Skin elasticity was measured with a cutometer and sagging severity was evaluated by using previously established photograph-based grading criteria. RESULTS: Facial skin vellus hairs were divided into three types: fine, thick, and normal thickness. Based on this observation, we established a 6-grade photograph-based grading system based on the dominant type of vellus hair in the target area and used it to evaluate vellus hair condition at the cheek. We found that vellus hair condition is significantly positively related to skin elasticity parameters Ua/Uf (representing overall elasticity including creep and creep recovery), Ur/Ue (representing net elasticity without viscoelastic creep), and Ur/Uf (ratio of elastic recovery to total deformation). Further, vellus hair condition was significantly negatively correlated to sagging severity. CONCLUSION: Our results suggest that vellus hair condition positively contributes to the skin's physical properties, and consequently deterioration of the vellus hair condition promotes an aged facial appearance.