[Protection against light in normal and diseased skin]

At the beginning of the holiday season dermatologists are regularily confronted with questions of light protection. Based on these questions and the respective replies the above subject is discussed. The following differentiation has to be considered: Cosmetical light protection. Light protection in case of pathological sensitivity to light. Light protection in case of light dermatoses. Besides a few exceptions (e.g. in the therapy of porphyria and similar diseases) light protection is a physical, absorptive process, i.e. a part of the UV rays is absorbed before reaching the skin. In abnormal light sensitivity, the UVA with longer wave lengths plays a part too, whereas for "normal skin" UVB with medium wave lengths is responsible for the light induced reactions. Details concerning selection, application, and effect of light protecting measurements are discussed.