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|Low level laser therapy|
|Low level laser therapy|
Low-level laser therapy (LLLT) is a form of laser medicine used in physical therapy and veterinary treatment that uses low-level (low-power) lasers or light-emitting diodes to alter cellular function. Other names for the therapy include low-power laser, soft laser, cold laser, biostimulation laser, therapeutic laser, and laser acupuncture. Whereas high-power lasers ablate tissue, low-power lasers are claimed to stimulate it and to encourage the cells to function.
LLLT is integrated with mainstream medicine with ongoing research to determine where there is a demonstrable effect. Areas of dispute include the ideal location of treatment (specifically whether LLLT is more appropriately used over nerves versus joints), dose, wavelength, timing, pulsing and duration. The effects of LLLT appear to be limited to a specified set of wavelengths of laser, and administering LLLT below the dose range does not appear to be effective.
Despite a lack of consensus over its scientific validity, specific test and protocols for LLLT suggest it may be mildly effective, but in most cases no better than placebo, in relieving short-term pain for rheumatoid arthritis, osteoarthritis, acute and chronic neck pain, tendinopathy, and possibly chronic joint disorders. The evidence for LLLT being useful in the treatment of low back pain, dentistry and wound healing is dubious.
LLLT has primarily been shown useful in the short-term treatment of acute pain caused by rheumatoid arthritis, osteoarthritis, tendinopathy, and possibly chronic joint disorders. LLLT has also been useful in the treatment of both acute and chronic neck pain. A Cochrane Library review concluded that low level laser therapy (LLLT) has insufficient evidence for treatment of nonspecific low back pain, a finding echoed in a later review of treatments for chronic low back pain. Though it has been suggested for decades that LLLT could be useful in speeding wound healing, the appropriate parameters (dose, type of laser, materials, wavelength, etc.) have not been identified. Similarly, the use of lasers to treat chronic periodontitis and to speed healing of infections around dental implants is suggested, but there is insufficient evidence to indicate a use superior to traditional practices.
Stephen Barrett, writing for Quackwatch, concluded there was evidence to support LLLT use for temporary pain relief, but "there's no reason to believe that they will influence the course of any ailment or are more effective than other forms of heat delivery."
FDA regulates all laser products, even handheld, battery-powered lasers that are available for purchase FROM manufacturers, importers, assemblers, dealers or distributors in the United States and its territories. This includes lasers manufactured or obtained on a continuing basis for the purpose of sale or resale.
FDA requires that manufacturers of these lasers limit the power of the laser light to 5 milliWatts (often abbreviated as "mW") or less. The labeling or packaging must allow the purchaser to know the power of the laser, its hazard class, and its wavelength before the laser is purchased. Even online advertisements must display this information for the purchaser.
Even the smallest handheld, battery-powered lasers are capable of emitting laser light at hazardous powers. Larger models, the size of a small flashlight, can burn skin and pop balloons. More importantly, consumers should assume any size handheld battery-powered laser they do not directly control has the potential to blind or permanently affect eyesight.
One way to determine if such a laser has been manufactured to regulatory power and hazard class limits is to find labeling. The labeling that comes with the laser (and online labeling) must display the power, hazard class, and wavelength. The wavelength is a number that describes the color of the beam.
The label must display the laser power. It must be 5 milliWatts or less. The label must display the hazard class. It must be Class I, Class IIa, Class II, Class IIIa or Class 1, Class 2 or Class 3R.
Do not purchase a handheld, battery-powered laser labeled with hazard Class IIIb, Class IV, Class 1M, Class 2M, Class 3B or Class 4 unless the manufacturer has an approval from FDA (called a "variance") to allow the purchase. Lasers approved for purchase in these classes often have very specific uses and may be sold under certain conditions known to the manufacturer. Sales without a variance, or sales that violate the conditions of the variance, ARE ILLEGAL. No laser, no matter what class or power, should be pointed at the eyes or reflected into the eyes from a mirror surface. No laser, no matter what class or power, is safe to shine at the operator of aircraft, watercraft, or vehicles. Laser light remains powerful and bright many miles or kilometers from the laser. Unlabeled lasers or lasers you do not control should be assumed dangerous, too powerful for most intended consumer uses, and could damage your eyesight from a momentary direct or indirect exposure to the beam. Handheld, battery-powered lasers have power and class limits for a reason; to prevent eye and skin damage. Laser light can damage eyesight in less time than you can blink or look away. Do not assume lasers offered for sale as "approved" or "safe" are not hazardous.
It is unclear how LLLT works. LLLT may reduce pain related to inflammation by lowering, in a dose-dependent manner, levels of prostaglandin E2, prostaglandin-endoperoxide synthase 2, interleukin 1-beta, tumor necrosis factor-alpha, the cellular influx of neutrophil granulocytes, oxidative stress, edema, and bleeding. The appropriate dose appears to be between 0.3 and 19 joules per square centimetre. Another mechanism may be related to stimulation of mitochondrion to increase the production of adenosine triphosphate resulting in an increase in reactive oxygen species, which influences redox signalling, affecting intracellular homeostasis or the proliferation of cells. The final enzyme in the production of ATP by the mitochondria, cytochrome c oxidase, does appear to accept energy from laser-level lights, making it a possible candidate for mediating the properties of laser therapy.
The effects of LLLT appear to be limited to a specified set of wavelengths of laser, and though more research is required to determine the ideal wavelengths, durations of treatment, dose and location of treatment (specifically whether LLLT is more appropriately used over nerves versus joints). Administering LLLT below the dose range does not appear to be effective. The factors of wavelength, effective dose, dose-rate effects, beam penetration, the role of coherence, and pulses (peak power and repetition rates) are still poorly understood in the clinical setting. The typical laser average power is in the range of 1-500 mW; some high-peak-power, short-pulse-width devices are in the range of 1-100 W with typical pulse-widths of 200 ns. The typical average beam irradiance then is 10 mW/cm2 - 5 W/cm2. The typical wavelength is in the range 600-1000 nm (red to near infrared), but some research has been done and products outside of this range are available.
In 1967 a few years after the first working laser was invented, Endre Mester in Semmelweis University in Budapest, Hungary experimented with the effects of lasers on skin cancer. While applying lasers to the backs of shaven mice, he noticed that the shaved hair grew back more quickly on the treated group than the untreated group.
At least one LLLT practitioner, Robert Lytle DDS, has been cited by the FDA for promoting non-FDA approved treatments on company websites.