Topography and anisotropy of the skin surface with ageing

Most studies of how the relief of the skin surface changes on ageing are based solely on topography, and a few have taken into account anisotropy parameters. However, the calculation of these parameters is often carried out manually and as the techniques of data acquisition have progressed rapidly, a certain degree of obsolescence has been reached. It is for this reason that we have undertaken a similar study but with more advanced equipment.

The Dermatop system analyses the relief of Silflo negative prints of the skin surface. It is based on the projection of interference fringes and phase shift and provides surface parameters and not profiles. In addition, the Toposurf software enables image processing and the precise and automatic calculation of the topography parameters (roughness, developed surface area and peak-trough amplitude) and anisotropy (level of anisotropy and furrow density). These parameters were studied on the forearm and temple of 40 men and 40 women evenly distributed into two groups: the first including subjects aged 25-35 years and the second 50-65 years.

Roughness of both sites increases with age, independent of sex, but to a lesser extent in women than in men. The developed surface area and the peak-trough amplitude increase significantly with age irrespective of the site and the sex. The level of anisotropy increases with age, in both men and women, on the forearm and the temple, the site more exposed to light being more affected. The density of the furrows decreases with age in both sexes and both sites but with a greater increase for the temple, which is more exposed to solar ageing.

The study of these new parameters will allow objective evaluation of the action of topical dermatological and cosmetic treatment, and new techniques in plastic surgery (e.g. laser resurfacing), and will enable the accurate follow-up of certain pathologies.