Laser, an acronym for Light Amplification by Stimulated Emission of Radiation, is a special form of electromagnetic energy that is located within the visible or infrared regions of the electromagnetic spectrum.¹ Unlike ultraviolet C (UVC) that has scientific evidence to support its use in wound management, laser therapy lacks scientific evidence at this time, specifically related to wound healing.^2–4 Although low-level laser therapy (LLLT) is used in many countries to promote wound healing, laser therapy is not currently approved by the FDA for wound management and is still considered an experimental treatment by most insurance companies in the United States.^3,5 Research on the effects of LLLT on wound healing has produced conflicting results due to inconsistency in treatment parameters used in various studies. If the proper LLLT parameters are not selected, the effectiveness of LLLT is reduced and can lead to negative treatment outcomes. These conflicting results, as well as a limited understanding of the biochemical effect of LLLT, contribute to the slow advancement of laser therapy for wound healing in the United States.⁶ This treatment, as with UVC, should only be performed by providers with expertise in the use of therapeutic technologies who rely heavily on research and evidence to determine the impact of therapeutic technologies on human tissue. The research on the impact of LLLT on wound healing does show promise for laser therapy having a specific role in wound management in the future.⁷

Because the average power of low-level lasers (or cold lasers) does not create an increase in tissue temperature, low-level lasers are the lasers of choice for wound treatment, and are classified as Class 3B/IIIb lasers.^1,8 Monochromatic light emitted from low-level lasers falls within the red visible or infrared wavelengths on the electromagnetic spectrum, between 600 and 1200 nm, as shown in FIGURE 20-1. The following three distinct properties of light are required characteristics of LLLs and are shown in FIGURE 20-2¹:

1. 
   

   Coherent: Photons that make up the light travel in a straight line.

   
   
2. 
   

   Monochromatic: Photons that make up the light have a single wavelength and therefore a single color.

   
   
3. 
   

   Collimation: Light is concentrated in one well-defined area.

The most common low-level lasers include those created by helium neon, gallium arsenide, and gallium aluminum arsenide. The differences between these three types of lasers are listed in TABLE 20-1.

The theory of low-level laser therapy is explained by a process called photobiomodulation. Photobiomodulation and other terminology used to discuss laser therapy are defined in TABLE 20-2. The light emitted by low-level lasers can penetrate the dermis and interact with many chromophores in the human tissues. This interaction can either stimulate or inhibit biological processes within these tissues, and therefore may positively impact wound healing. Some of the biological processes that appear to be affected by photobiomodulation include increased fibroblast proliferation, macrophage activity, collagen synthesis, and oxygen availability to tissues.^9–13

Low-level laser therapy is thought to impact wound healing at the cellular level by reducing the number of cellular enzymes and chemicals associated with pain and inflammation.^14–16 LLLT is also thought to stimulate the production of enzymes that enhance cell proliferation and cell division. Research has shown that LLLT stimulates macrophage activity, causing an increase in the release of chemical mediators involved with fibroblast production.^4,17 In addition, studies have shown an increase in collagen synthesis in human tissues after treatment with LLLT.^8,18 One study demonstrated an increase in the ability of oxygen to disassociate from hemoglobin, thus making the oxygen more available for transfer to hypoxic tissues, when treated with LLLT.⁸ In addition to these positive effects on wound healing, research has also supported the use of LLLT to affect human biological processes such as muscle cell proliferation, ATP synthesis, and immune system function.^8,19–21

Without the FDA approval for wound healing, clinicians must rely on existing research to determine appropriate indications for low-level laser therapy. These indications may include recalcitrant wounds, necrotic wounds, and infected or colonized acute or chronic wounds.²² One study found that a combination of medicinal honey and LLLT (904 nm) reduced inflammation and pain in full-thickness burns.²³ Although no adverse reactions to LLLT have been reported, the following precautions and contraindications are advised:

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  During the first trimester of pregnancy

  
  
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  Over cancerous growths

  
  
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  Over thyroid tissue

  
  
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  Direct exposure to the eyes (could result in a retinal burn)