Investigation of the relationship between wrinkle formation and deformation of the skin using three-dimensional...

Although there have been many studies investigating facial movements using three-dimensional (3D) quantitative analysis, the possible relationship between the levels of wrinkles and the movement distance of facial skin has previously not been reported.

Forty-four healthy Japanese women (from 20 to 50 years, average = 47.7 ± 3.6 years) were recruited for this study with written informed consent. Infrared reflective marks were attached on their forehead skin, and then moving images of facial skin motions (raising the eyebrows) were captured using two infrared cameras under infrared ray irradiation. Calibration for the absolute value of distance was established using an exact one-point 3-m cube having infrared reflective marks at each apex. The two pupils and the top of the nose were setup as fixed standard points. 3D motion analysis was then carried out using Move-tr/3D(™) software to determine the absolute distances of skin surface movements. Levels of wrinkles were determined using a 3D roughness analyzer (PRIMOS) directly at rest and when raising the eyebrows.

The wrinkle levels at rest showed a relatively high and significant correlation with wrinkles when strongly raising the eyebrows. Although the wrinkle levels at rest showed no correlation with the movement distance, the wrinkle levels when raising the eyebrows showed a significant correlation with the movement distance. The ratio of change based on the distance between the marks at rest and when raising the eyebrows showed similar correlation results.

These results suggest that both the levels of skin deformation caused by movements and the wrinkles at rest are important factors that determine the wrinkle level when raising the eyebrows. However, the level of skin deformation is not important for wrinkle levels at rest, which indicates that other factors such as skin elasticity are also important for the formation of wrinkles.