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Abstract
Corynebacterium acnes synthesizes porphyrins. Partially or totally closed sebaceous glands show particularly high fluorescence intensity. Many comedos, especially in the nasolabial fold, may be detected in this way. To attain quantitative data on the density of facial comedos, definite skin sites were to be investigated following regular application of products to be analyzed for comedogenicity. This was performed in the following way: skin sites irradiated with long-wave ultraviolet A light; recording of the resulting yellow fluorescence by a light-amplifying video camera; suppression of reflection by special filters; and image analysis to count and measure the size of the yellow spots.
The influence of pretreatment on signal intensity and its parallel determination by commercial, light-guide-equipped fluorometers will be discussed. The relation between visual and instrumental counting will be shown. The comedogenicity of raw materials, products, and skin care products is reported.