Direct and non-direct measurement techniques for analysis of skin surface topography.

Estimation of skin smoothness is of ever-increasing interest especially in the field of cosmetic research. There are some established methods for assessing skin smoothness, e.g. optical and mechanical profilometry, but the presentation of recently developed new methods reflects the demand for alternatives which are more precise and practical. For fundamental research on ultrastructure of the stratum corneum surface scanning electron microscopy is a suitable method. A direct method is the surface evaluation of living skin, which is based on an optical system in a CCD camera measuring four parameters of roughness, scaling, smoothing and wrinkling. A similar but non-direct method is optical profilometry using skin replicas. Laser profilometry produces a variety of data which can be analysed using complex mathematical functions. A promising new method is transparency profilometry (skin visiometer) using a very thin skin print which allows parallel light to pass through and is analysed immediately after production. The different methods can be used for characterization of the skin microrelief in dermatoses or for dynamic measurements of time-dependent changes in skin surface topography after application of cosmetic or medical products.