Low-level light/laser therapy versus photobiomodulation therapy.

As Juliet states: ‘‘What’s in a name? That which we call a rose by any other name would smell as sweet.’’ However, a name, if ill-conceived and lacking a clear definition, can have profound effects on the image and acceptance of a therapy by mainstream medicine. Sunlight has much anecdotal use in ancient scriptures. In the late eighteenth century, Niels Ryberg Finsen pioneered the use of red and blue light to treat various human ailments, especially Lupus vulgaris. He was awarded the Nobel Prize in medicine and physiology in 1903 for his pioneering demonstration that concentrated chemical rays from sunlight could be bactericidal as well as stimulating surrounding tissue. Although this seminal work received much attention from physicians and scientists, the lack of mechanistic explanation relegated it non-mainstream medicine. The second major milestone in therapeutic use of light began with the invention of laser technology in the early 1960s. Given its electromagnetic nature and significant destructive power, there were immediate concerns about its biological safety. Among the earliest studies to assess effects of lasers on biological tissues were the standard dose escalation studies that many laboratories immediately began to perform. Mester et al. noted that laser light at low doses demonstrated increased hair growth at an accelerated rate, and promoted excisional wound healing. This observation was termed ‘‘laser biostimulation.’’ Thus, the specialized field of phototherapy that utilizes low-dose light for clinical therapy was reborn. Since then, the field has matured, and much has been learned about the mechanistic basis of this therapy, including a key fact that this application of light to tissues and organisms can elicit both stimulatory and inhibitory responses, depending upon the light parameters used. In addition to biostimulation, a few of the other names previously used for this therapy have included low-level laser (or light) therapy (LLLT), low-intensity laser therapy, lowpower laser therapy, cold laser, soft laser, photobiostimulation, and photobiomodulation. There is clearly a dismal lack of consistency and consensus on terminology. The most frequently used term is low-level laser therapy (LLLT). LLLT is the often-cited Medical Subject Headings (MeSH) term contained in the National Library of Medicine’s controlled vocabulary thesaurus. This term is ambiguous, as the words ‘‘low’’ and ‘‘level’’ are vague and not accurately definable, whereas the word ‘‘laser’’ is no longer appropriate, as other types of light devices such as LEDs and broadband light sources are currently used for this application. A nomenclature consensus meeting was organized under the auspices of the joint conference of the North American Association for Light Therapy and the World Association for Laser Therapy in September, 2014. It was attended by 15 international participants and co-chaired by Drs. Jan Bjordal and Juanita Anders (see Acknowledgments). Several key points were discussed in this meeting. The two major highlights are summarized here.