Photobiomodulation
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- Not to be confused with Light therapy.
Photobiomodulation, also known as low level laser therapy (LLLT), cold laser therapy, and laser biostimulation, is a controversial medical and veterinary technique in which exposure to low-level laser light is claimed to enhance tissue growth and have other beneficial effects.[1] The technique is also known by the more ambiguous terms phototherapy and laser therapy, which may also be used to describe other medical techniques.
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[edit] History
In 1967 a few years after the first working laser was invented, Endre Mester in Semmelweis University Budapest, Hungary wanted to find out if laser light could cause cancer. He took some mice, shaved the hair off their backs, divided them into two groups and gave a laser treatment with a low-powered ruby laser to one group. They did not get cancer and to his surprise the shaved hair grew back more quickly on the treated group than the untreated group. That was how "laser biostimulation" was discovered.[2]
[edit] Clinical applications
Clinical applications include treating soft tissue injuries and chronic pain, aiding wound healing and nerve regeneration, and possibly even resolving viral and bacterial infections.
[edit] Mechanism
Certain wavelengths of light at certain intensities (delivered by laser, LED or another monochromatic source) will aid tissue regeneration, resolve inflammation, relieve pain and boost the immune system.[citation needed] The exact mechanism is still being explored and debated but it is agreed that the mechanism is photochemical rather than heat-related.[citation needed] Observed biological and physiological effects include changes in cell membrane permeability, up-regulation and down-regulation of adenosine triphosphate and nitric oxide.
Contentious areas are: "best" wavelength, dose, dose-rate effects, beam penetration, the role of coherence and pulses (peak power and repetition rates). Laser average power is typically in the range of 1-500 mW; some high peak power, short pulse width devices are in the range of 1-100 W with typically 200 ns pulse widths. The average beam irradiance then is typically 10 mW/cm2 - 5 W/cm2.[citation needed] The wavelength is typically in the range 600-1000 nm but some research has been done and products are available outside this range.
[edit] Safety
There appear to be no safety concerns in its application for therapy in people or animals, but the operator and patient should wear appropriate protection for the eyes (dense filter spectacles) in case of accidental or reflected exposure, and the laser beam should never be directed at the eyes.
- See also: laser safety
[edit] See also
[edit] References
- ^ Mecahnisms for low-light therapy. Photonics West BiOS 2007 Conference announcement. Retrieved on 2006-09-17.
- ^ Mester, E., Szende, B., and Tota, J.G. (1967). "Effect of laser on hair growth of mice". Kiserl Orvostud 19: 628-631.
