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11 December 2018 Review of light parameters and photobiomodulation efficacy: dive into complexity
Randa Zein, Wayne Selting, Michael R. Hamblin
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Journal of Biomedical Optics, Vol. 23, Issue 12, 120901 (December 2018). https://doi.org/10.1117/1.JBO.23.12.120901
Abstract
Photobiomodulation (PBM) therapy, previously known as low-level laser therapy, was discovered more than 50 years ago, yet there is still no agreement on the parameters and protocols for its clinical application. Some groups have recommended the use of a power density less than 100  mW/cm2 and an energy density of 4 to 10  J/cm2 at the level of the target tissue. Others recommend as much as 50  J/cm2 at the tissue surface. The wide range of parameters that can be applied (wavelength, energy, fluence, power, irradiance, pulse mode, treatment duration, and repetition) in some cases has led to contradictory results. In our review, we attempt to evaluate the range of effective and ineffective parameters in PBM. Studies in vitro with cultured cells or in vivo with different tissues were divided into those with higher numbers of mitochondria (muscle, brain, heart, nerve) or lower numbers of mitochondria (skin, tendon, cartilage). Graphs were plotted of energy density against power density. Although the results showed a high degree of variability, cells/tissues with high numbers of mitochondria tended to respond to lower doses of light than those with lower number of mitochondria. Ineffective studies in cells with high mitochondrial activity appeared to be more often due to over-dosing than to under-dosing.
© 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)
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Randa Zein, Wayne Selting, and Michael R. Hamblin "Review of light parameters and photobiomodulation efficacy: dive into complexity," Journal of Biomedical Optics 23(12), 120901 (11 December 2018). https://doi.org/10.1117/1.JBO.23.12.120901
Received: 4 April 2018; Accepted: 14 November 2018; Published: 11 December 2018
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Cited by 182 scholarly publications and 10 patents.
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KEYWORDS
Tissues
Wound healing
In vitro testing
In vivo imaging
Bone
Brain
Photons
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