As defined, photobiomodulation therapy is a nonthermal process, yet there is a soothing warmth. What is the explanation?
As shown in the animation, light that penetrates into the tissue can be absorbed by melanin, hemoglobin, oxyhemoglobin, water, and other endogenous tissue chromophores. Energy from these absorption events will be dissipated as heat, generating a soothing warmth in the tissue. This is not considered as part of the photobiomodulation process.
Other laser manufacturers have suggested that the higher power lasers can cause damage. Is this true?
The higher power lasers are able to treat a larger area in a shorter time. There is some absorption of the light by other chromophores which does generate a soothing warmth. This generated heat is safe. The FDA approval of the therapy lasers is for this warmth for elevating tissue temperature for temporary relief of minor muscle and joint pain, muscle spasm, pain and stiffness associated with arthritis and promoting relaxation of the muscle tissue and to temporarily increase local blood circulation. Practitioners are carefully instructed on the proper techniques to safely deliver a therapeutic dose to patients.
Other laser manufacturers suggest that research has not been done with higher power lasers. Is this true?
Much of the understanding of the mechanisms of PBM has been done with cell studies and numerous studies that have been performed on mice and rats. Many of these studies have been done with lower power lasers. In order for PBM to occur, the photons need to reach the damaged tissue. Much of the early clinical research on PBM therapy was with low dose and unremarkable results. However, there are now published studies that have used higher power lasers and with significantly better results.9-15
