LED vs Laser Light Therapy

Why are lasers preferred over LEDs for pain management?

Are all photobiomodulation therapy (PBMT) devices created equal?

Photobiomodulation (PBM) is a technique using low-power laser or light emitting diodes (LEDs) to modulate inflammation, accelerate wound healing, and reduce pain and discomfort in different clinical situations.

Photobiomodulation has been studied and used in the treatment of a variety of clinical indications. Each of these applications is based on the biological effects of photobiomodulation in living organisms.

Are the benefits of therapy different between devices that use LEDs and devices that use lasers to deliver the energy dose? The answer depends on the desired effect; for example, the depth of penetration of light is different between lasers and LEDs. Lasers deliver coherent light, LEDs do not. LEDs can collimate (or actively align) light waves using a focusing lens but cannot achieve the same properties as lasers.

Curavi uses laser diodes instead of LEDs due to the unique characteristics of the laser light:

Laser Light is:

 

  • Nearly monochromatic – consists of an extremely narrow range of wavelengths;  
  • Highly directional – travels in a single direction within a narrow cone of divergence; and  
  • Highly coherent – coherence is the most fundamental property of laser light.  
  • Coherence of light is responsible for distance traveled and depth of matter penetration.  
  • Coherence of light is what allows the energy to penetrate tissue to a deeper level.

Wavelength

The Laser Diode (LD) delivers a divergent beam of true laser energy, where all photons are exactly the same color and in phase in time and space. With the addition of a set of collimating optics, a parallel beam is achieved, as in a laser pointer. This means the beam can be focused to an extremely small point with a lens, such as the ocular lens, showing how LDs can pose a real ocular hazard.

The LED also delivers a divergent beam, with most of the photons at the rated wavelength, but totally out of phase, giving non-coherent, yet quasi-monochromatic light. It is impossible to force collimation on LED energy, and therefore precise focusing is also impossible.

Semicollimation can, however, be achieved, giving a less divergent beam and hence increasing the photon intensity to give a better phototherapeutic effect.

Laser light flows in phase – it does not spread appreciably over distance. LEDs are non-coherent (spread) and do not travel as far due to signal degeneration. Summary – laser light is much more concentrated (coherent) than LEDs, which makes it ideal for medical therapeutic use.

Lasers have been proven to help manage pain and have been cleared by the Food and Drug Administration (FDA) for that purpose. Devices that use LEDs may fall short of providing the power output (and tissue penetration of energy) required for pain management and inflammation.

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