Acne vulgaris.

Acne vulgaris is one of the most common dermatological diseases, and caused by a combination of pathogenetic factors including follicular hyperkeratosis, seborrhea, colonization with Propionibacteriumacnes and inflammatory phenomena. Various medical treatments address these causative factors, but they are not always well tolerated. In the last decades, there has been increased interest in laser and light-based treatments. These optical devices mainly target Propionibacteriumacnes by activating porphyrins produced by the bacterium, whereas some treatments directly lead to the destruction of sebaceous glands. Photodynamic therapy can enhance these effects through the prior application of a photosensitizing agent. Many laser and light-based treatments have shown excellent clinical results in the reduction of inflammatory acne lesions and improved acne severity. Although relapses are frequent, results can be improved by combination therapy with conventional medical treatments. Data of randomized controlled studies or studies with a split-face design are contradictory and difficult to compare. Furthermore, the cost of the treatments is often a limiting factor. In summary, some optical devices are an important additional tool in the treatment of patients with mainly inflammatory acne where conventional treatments are not well tolerated.