Effect of pulsing in low-level light therapy.
OBJECTIVE
Low level light (or laser) therapy (LLLT) is a rapidly growing modality used in physical therapy, chiropractic, sports medicine and increasingly in mainstream medicine. LLLT is used to increase wound healing and tissue regeneration, to relieve pain and inflammation, to prevent tissue death, to mitigate degeneration in many neurological indications. While some agreement has emerged on the best wavelengths of light and a range of acceptable dosages to be used (irradiance and fluence), there is no agreement on whether continuous wave or pulsed light is best and on what factors govern the pulse parameters to be chosen.


METHODS
The published peer-reviewed literature was reviewed between 1970 and 2010.


RESULTS
The basic molecular and cellular mechanisms of LLLT are discussed. The type of pulsed light sources available and the parameters that govern their pulse structure are outlined. Studies that have compared continuous wave and pulsed light in both animals and patients are reviewed. Frequencies used in other pulsed modalities used in physical therapy and biomedicine are compared to those used in LLLT.


CONCLUSIONS
There is some evidence that pulsed light does have effects that are different from those of continuous wave light. However further work is needed to define these effects for different disease conditions and pulse structures.
Hashmi
Javad T
JT
Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts, USA.
Huang
Ying-Ying
YY
Sharma
Sulbha K
SK
Kurup
Divya Balachandran
DB
De Taboada
Luis
L
Carroll
James D
JD
Hamblin
Michael R
MR
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002545:Brain Ischemia / Q000628:therapy; D002540:Cerebral Cortex / Q000378:metabolism; D006801:Humans; D007834:Lasers; D028022:Low-Level Light Therapy / Q000379:methods; D009416:Nerve Regeneration / Q000528:radiation effects; D009431:Neural Conduction; D059408:Pain Management; D020521:Stroke / Q000628:therapy; D014945:Wound Healing / Q000528:radiation effects
D000255:Adenosine Triphosphate