Felis ISSN 2398-2950

Laser therapy: overview

Synonym(s): Class IV laser therapy; Low level laser therapy (LLLT); Photobiomodulation

Contributor(s): Stephen Barabas, David R Mason

Introduction

  • LASER is an acronym for Light Amplification by the Stimulated Emission of Radiation. Lasers emit light in a different manner than other sources. Light is monochromatic, coherent, and collimated.  Light energy is emitted as photons and interacts with tissues. Lasers that interact photo-thermally via long pulses exert a biological effect via heating and include surgical / hair removal lasers. Therapy lasers exert a biochemical change/response (Photobiomodulation) to promote tissue healing / pain relief.
  • Photobiomodulation is the absorption of monochromatic visible and near infrared (760-1440 nm) light via components of the cellular chain called chromophores. Cytochrome c oxidase is the terminal enzyme of the respiratory chain in eukaryotic cells mediating the transfer of electrons from cytochrome c to molecular oxygen and is considered the primary chromophore and photosignal transducer. Electron transfer in the mitochondria is accelerated once photons are absorbed and primary reactions in mitochondria of eukaryotic cells are followed by a cascade of secondary reactions occurring in the cytoplasm, cell membrane and nucleus including the promotion of cellular respiration, production of ATP and NO, as well as beneficial reactive oxygen species (ROS).
  • We come into contact with lasers everyday - they are used in electronic devices, bar code readers, diagnostic x-rays, surgical and industrial cutting tools, and can be used for tissue biostimulation.
  • Specific wavelengths of laser were proven to have a bio-stimulatory (acceleration of healing) effect on in vivo animal tissues with in the red and infra-red wavelengths of the electromagnetic spectrum in the 1960's .
  • Scientific research over the last sixty years has further refined our knowledge and understanding of the biological effects of laser therapy on target molecules, different tissues and the depth of penetration into living bodies .
  • Lasers are classified according to power settings and their potential deleterious effects on the retina of subjects (ANSI Classification) .
    • Class I lasers (micro Watts) are the weakest - internal electronics.
    • Class II lasers (<1mW) - grocery scanners and pen pointers.
    • Class III a and b (<500mW) - original medical lasers and light shows.
    • Class IV (>500mW) - medical lasers, industrial, surgical and military.
    • Class IIIb and Class IV lasers require use of protective goggles.
  • Commercially available medical lasers were first used in the 1980's and were weak Class II and Class IIIb lasers (<0.5W max power).
  • Class IV lasers were proven safe for medical therapeutic use in the early 2000's by the FDA and EU regulatory bodies, and in the last decade there has been an explosion of growth in both human and veterinary medical use.
  • Class IV lasers have shorter time protocols than Class IIIb allowing, faster treatment sessions with larger areas or deeper tissues stimulated over similar time frame.
  • Medical therapeutic lasers have been proven in double-blinded, placebo controlled studies to stimulate healing and pain management, from acute to chronic, non-healing diabetic wounds, and from sports injuries to deep musculoskeletal post-surgical rehabilitation .
  • Power settings and pulse frequency variations can be changed to treat different tissues from superficial wounds, to gingivae, muscle injuries, deep osteoarthritic joint pain, or neurological central nervous disorders .
  • The combined effects of wavelength, power (J/s or Watts) and pulse frequency (Hz) have a profound effect of a wide range of different tissues and conditions.
  • Modern therapeutic lasers provide phased protocols which are calibrated to treat varying chronicities of disorders and levels of pain, whilst calibrating for depth of penetration, skin/coat color and size of individuals.
  • Due to the ease of use, modern Class IV laser therapy has been adopted recently by vets, physiotherapists and nurses working within busy vet practices, referral hospitals or universities across the globe.

Indications

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Advantages and disadvantages

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Physiological and biological effects

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Frequently asked questions

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Laser safety

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Further Reading

Publications

Refereed Papers

  • Recent references from VetMed Resource and PubMed.
  • Chung H et al (2012) The nuts and bolts of Low level laser light therapy. Ann Biomed Eng 40 (2), 516-533 PubMed.
  • Baltzer W et al (2011) Preoperative LLLT in dogs undergoing tibial plateau levelling osteotomy: double-blinded, placebo-controlled clinical trial. (awaiting publication)
  • Carvalho R L (2010) Effects of Low-Level Laser therapy on pain and scar formation after inguinal herniation surgery: A randomized controlled single-blind study. Photomedicine and Laser Surgery 28 (3), 417-422 PubMed.
  • Chow R T et al (2009) Efficacy of LLLT in the management of neck pain: a systematic review and meta-analysis of randomised placebo or active treatment controlled trials. The Lancet  374, 1897-1908 PubMed.
  • Minatel D G (2009) Phototherapy promotes healing of chronic diabetic leg ulcers that failed to respond to other therapies. Lasers in Surgery and Medicine 41, 433-441 PubMed.
  • Oliveira F S et al (2009) Effects of LLLT (830nm) with different therapy regimes on the process of tissue repair in partial lesion calcaneous tendon. Lasers in Surgery and Medicine 41, 271-276 PubMed.
  • Khadra M et al (2005) Effects of laser therapy on attachment, proliferation and differentiation of human osteoblastic like cells attached on titanium implant materials. Biomaterials 26, 3503-3509.
  • Manteifel V M & Karu T I (2005) Structure of mitochondria and activity of their respiratory chain in successive generation of yeast cells exposed to He-Ne laser light. Biology Bulletin 32 (6),  556-566.
  • Enwemeka C S et al (2004) The efficacy of Low power lasers in tissue repair and pain control: a meta-analysis study. Photomedicine and Laser Surgery 22 (4), 323-329 PubMed.

Other sources of information

  • Cardona M (2013) Treatment of immune-mediated neutrophilic vasculitis in a Shar Pei with Low level laser therapy. SEVC 2013.
  • Stephens B, Baltzer W & Harrington P (2011) Internal dosimetry: combining simulation with phantom and ex vivo measurements. NAALT Congress 2011.
  • Health and Safety (2010) The Control of Artificial Optical Radiation at Work Regulations 2010 No. 1140.


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