Nomenclature Consensus Meeting
WALT-NAALT 2015, Arlington VA
Report prepared by Juanita J. Anders, Ph.D.

The Nomenclature Consensus Meeting was held in September, 2014 at the joint conference of the North American Association for Light Therapy and the World Association for Laser Therapy. It was co-chaired by Drs. Bjordal and Anders. The following international stakeholders participated in the discussions: Juanita Anders, Praveen Arany, David Baxter, Jan Bjordal, James Carroll, Roberta Chow, Lars Hode, Peter Jenkins, Donald Patthoff, Gerry Ross, Anita Saltmarche, Clark Tedford, Patricia Trimmer, Jerry True, and Nicholas Wise.

An initial presentation was made by James Carroll on the history of terms used for this therapy. Beginning in the 1960s, Mester noted that laser light caused hair to grow at an accelerated rate and led to the use of the term "laser biostimulation" (1). Since then, the field has matured and much has been learned about the mechanistic basis of this therapy, including the fact that Photobiomodulation therapy can be stimulatory or inhibitory depending on the light parameters used. A few of the other names previously used for this therapy included low-level laser (or light) therapy (LLLT), low intensity laser therapy, low power laser therapy, cold laser, and soft laser. Of these, the most frequently used term was low level laser therapy (LLLT). Thus, there has been a lack of consistency and consensus on terminology.

The following pros and cons of several terms were discussed as summarized below:

 Light Therapy or Phototherapy

Participants liked the simplicity of these terms. However, these terms are very broad and can include therapies that do not fit the criteria for photobiomodulation such as being non-thermal, light with wavelengths in the visible and near-infrared portion of the spectrum, absorption by endogenous chromophores, and effects that do not require classic, visual pathways (such as treatment for seasonal affective disorder).

Low Level Light Therapy (LLLT)

This is a well-established term included in the Medical Subject Headings (MeSH) term of the National Library of Medicine’s controlled vocabulary thesaurus (2). However this term is vague since the words “low” and “level’ are not defined and the word laser is no longer accurate since other types of light devices are currently used for this therapy (3). It is a very broad term that could include photodynamic therapy and optogenetics, two techniques which require exogenous chromophores unlike this therapy which utilizes endogenous chromophores.

Photobiomodualtion / Photobiomodulation Therapy

Photobiomodulation was considered by the majority of the participants as the term of choice to describe this therapy. This term has specificity and emphasizes its scientific basis. However, a main criticism of the term was that Photobiomodulation therapy was not a MeSH term of the National Library of Medicine’s controlled vocabulary thesaurus. Also some participants expressed concern that this term may be difficult for patients to use.

The meeting ended with the following recommendations:

To encourage the universal use of the term Photobiomodulation/ Photobiomodulation Therapy.
To continue to develop the definition of Photobiomodulation Therapy with input from the stakeholders.
For Dr. Arany to continue efforts to have Photobiomodulation Therapy added as a MeSH term of the National Library of Medicine’s controlled vocabulary thesaurus.

Update (Jan 2015):

It is a great pleasure to report that it was recently announced that “Photobiomodulation Therapy” will be added to the MeSH vocabulary for the 2016 version of the vocabulary thesaurus. It has been added as an entry term to an existing record, Low Level Light Therapy, and will be indexed with the terms on this record starting in November, 2015. Thanks to support of many of the participants of this meeting and others, especially Dr. Arany who worked with representatives of the MeSH Section at the National Library of Medicine for the success of this effort. Addition of Photobiomodulation Therapy to the MeSH vocabulary is an important step in defining what this therapy represents.
A suggested definition of Photobiomodulation Therapy is as follows:
“A light therapy that utilizes non-ionizing light sources, including LASERS, LEDs, and broad-band light, in the visible and infrared spectrum. It is a non-thermal process involving endogenous chromophores eliciting photophysical (i.e. linear and non-linear) and photochemical events at various biological scales. This process results in beneficial therapeutic outcomes including but not limited to the alleviation of pain or inflammation, immunomodulation, and promotion of wound healing and tissue regeneration.”

Note that specific diseases or trauma are not included in the definition. What is included are the broad therapeutic benefits supported by sound preclinical and clinical data and that are integral to the therapeutic resolution of many conditions.