Laser therapy has been performed for about 50 years. Initially, with quite low power between 1-5 mW HeNe laser (Prof. Mester), namely for wound healing. Later, higher power followed in the range of therapy laser class 3B up to 500 mW (Low-Level-Laser-Therapy, LLLT). Therapeutic application was extended to class 4 lasers about 10 years ago (High-Level-Laser-Therapy, HLLT, class 4 laser devices).