When UVA light strikes the surface of the Stratum Corneum (SC), particularly when the SC is dry, the dry corneocytes exhibit strong fluorescence, resulting in the emission of visible light. This phenomenon of UV-induced visible light fluorescence forms the basis of the Visioscan VC 20plus camera (Courage and Khazaka, Cologne, Germany), which is commonly used for imaging dry skin. In addition to its use for dry skin, this technique has also been applied in the imaging of psoriasis, mosaic melanoderm patterns, and residual sunscreen on the skin.

By capturing images, the Visioscan not only visualizes the skin’s surface but also allows for analysis of dry skin. Dry areas, which fluoresce more intensely and appear white, can be quantitatively assessed to determine the extent and distribution of dryness. The tool is especially useful for tracking changes in skin dryness over time, offering a detailed view of how different skin conditions progress.