[Photodynamic therapy: principles and therapeutic indications].

Photodynamic therapy consists in destroying a tumoral or a non tumoral tissue by the effect of both a photosensitizing molecule and a laser light. This simple concept has needed numerous years in order to be used in routine treatments with both photosensitizers and laser light delivered optimally. Researches in chemistry lead to new porphyrin and bacteriochlorophyl derivatives which alleviate the decrease of light absorption by endogenous molecules and in consequence allow a deeper light penetration. Short half-life of these compounds allows an easier treatment monitoring. In parallel, improvements in both laser technology and fibers allow new indications in various pathologies. First applications took place in treatment of respiratory, digestive and urologic cancers. The biggest success to date is recorded in ophthalmology with the treatment of age related macular degeneration. New approaches are explored and clinical studies are ongoing.