Since the method was first tested on test animals in the late 1960’s, more than 2500 studies have been published. A large part of these were cell and animal studies. Several are clinical studies – of these clinical studies, 145 have been double-blinded studies. This means that neither the therapist, patient or researcher know, if a real laser or a “dummy laser” was used for treatment: This eliminates the possibility of biases.
Of these 145 clinical studies, 105 found laser treatment to have a statistically significant positive effect. This however means that 1/3 did not show laser treatment to have an effect. By the late 1960’s researchers had found that different wavelengths of light had varying effects – among other reasons, because they had different depths of penetration. They also discovered that a minimum dosage is required for laser treatment to have an effect and that the treatment approach should change according to the biological conditions. The researchers who conducted the “negative” studies seem to have been limited in their knowledge of laser therapy.
This is evidenced by their use of extremely low dosage, incorrect calculations of dose and poor treatment technique, etc. Some negative studies seem to reach legitimate conclusions. They confirm that not all conditions can be affected, or simply, that the wavelengths of lights and/or doses used in the study were insufficient for a biological response.
One can therefore safely assert that laser therapy has a solid scientific basis. It definitely has enough basis to be accepted as a medical treatment method. Due to the complexity of laser treatment there is obviously a need for further scientific research, e.g. to determine optimal doses and treatment techniques.