What is Laser Therapy?
Foundational Science and History of Laser Therapy
How Laser Therapy Works
All light is composed of photons: small packets of light energy in the form of waves with a defined frequency and wavelength. However, not all light is the same. Different wavelengths of light represent different colors on the light spectrum. When light is projected as a single, coherent wavelength where the waves travel parallel to each other, it’s considered laser light. Laser light is much more intense than regular white light and has a multitude of applications from scanning barcodes to treating pain, inflammation, and more within human (and animal) bodies.
Laser therapy is when laser light is tuned to specific wavelengths and frequencies and applied to an organism in order to stimulate metabolic processes at the cellular level.
Laser light holds its intensity until it is absorbed by a medium; in the case of laser therapy, the medium is the body. The photon energy of laser light can effectively penetrate the skin and underlying structures, which accelerates the body’s natural healing process. Laser therapy utilizes the wavelengths and frequencies of visible red and near infrared (NIR) light to treat a variety of conditions at their source within the body through safe, non-invasive, and painless procedures.
Studies have shown that when tissue cultures are irradiated by lasers, enzymes within cells absorb energy from laser light. Visible red light and near infrared (NIR) are absorbed within the mitochondria and the cell membrane. This produces higher ATP levels and boosts DNA production, leading to an increase in cellular health and energy.
Therefore, when applied as treatment, lasers have been shown to reduce pain and inflammation as well as stimulate nerve regeneration, muscle relaxation, and immune system response. Lasers have no effect on normal tissues because photons of light are only absorbed and utilized by the cells that need them.
Role of Chromophores
Chromophores are components of various cells and subcellular organelles which absorb light. The stimulation of chromophores on mitochondrial membranes incites the production of ATP.
This results in:
- Increased cellular energy levels
- Pain relief
- Accelerated cellular healing
How does Laser Therapy Reduce Inflammation?
1. Stabilization of the cellular membrane: Ca++, Na+ and K+ concentrations, as well as the proton gradient over the mitochondrial membrane are positively influenced. This is accomplished in part, by the production of beneficial Reactive Oxygen Species aka (ROS). These ROS’s modulate intracellular Ca++ concentrations and laser therapy improves Ca++ uptake in the mitochondria.
2. Enhancement of ATP production and synthesis: ATP production and synthesis are significantly enhanced, contributing to cellular repair, reproduction and functional ability. Photonic stimulation of Cytochrome c Oxidase, a chromophore found on the mitochondria of cells, plays a major role in this rapid increase in production and synthesis of ATP.
3. Stimulation of vasodilation: Vasodilation is stimulated via an increase in Histamine, Nitric Oxide (NO) and Serotonin levels, resulting in reduction of ischemia and improved perfusion. Laser-mediated vasodilation enhances the transport of nutrients and oxygen to the damaged cells and facilitates repair and removal of cellular debris.
4. Acceleration of leukocytic activity: Beneficial acceleration of leukocytic activity, resulting in enhanced removal of non-viable cellular and tissue components. Thus allowing for a more rapid repair and regeneration process.
5. Acceleration of leukocytic activity: Beneficial acceleration of leukocytic activity, resulting in enhanced removal of non-viable cellular and tissue components. Thus allowing for a more rapid repair and regeneration process.
6. Increased prostaglandin synthesis: Prostaglandins have a vasodilating and anti-inflammatory action
7. Reduction in interleukin 1: Laser irradiation has a reducing effect on this pro-inflammatory cytokine that has been implicated in the pathogenesis of rheumatoid arthritis and other inflammatory conditions.
8. Enhanced lymphocyte response: In addition to increasing the number of lymphocytes, laser irradiation mediates the action of both lymphatic helper T-cells and suppressor T-cells in the inflammatory response. Along with laser modification of beta cell activity, the entire lymphatic response is beneficially affected by laser therapy.
9. Increased angiogenesis: Both blood capillaries and lymphatic capillaries have been clinically documented to undergo significant increase and regeneration in the presence of laser irradiation.
10. Temperature modulation: Areas of inflammation typically demonstrate temperature variations, with the inflamed portion having an elevated temperature. Laser therapy has been shown to accelerate temperature normalization, demonstrating a beneficial influence on the inflammatory process.
11. Enhanced superoxide dismutase (SOD) levels: Laser stimulated increases in cytokine SOD levels interact with other anti-inflammatory processes to accelerate the termination of the inflammatory process.
12. Decreased C-reactive protein and neopterin levels: Laser therapy has been shown to lower the serum levels of these inflammation markers, particularly in rheumatoid arthritis patients
How does Laser Therapy Reduce Pain?
1. Increase in beta endorphins: The localized and systemic increase of this endogenous peptide, after laser therapy irradiation has been clinically reported in multiple studies, to promote pain reduction.
2. Increased nitric oxide production: Nitric oxide has both a direct and indirect impact on pain sensation. As a neurotransmitter, it is essential for normal nerve cell action potential in impulse transmission activity. And indirectly, the vasodilation effect of nitric oxide can enhance nerve cell perfusion and oxygenation.
3. Decreased bradykinin levels: Since Bradykinins elicit pain by stimulating nociceptive afferents in the skin and viscera, mitigation of elevated levels through laser therapy can result in pain reduction.
4. Ion channel normalization: Photobiomodulation promotes normalization in Ca++, NA+ and K+ concentrations, resulting in pain reduction as a result of these ion concentration shifts.
5. Blocked depolarization of C-fiber afferent nerves: The pain blocking effect of therapeutic lasers can be pronounced, particularly in low velocity neural pathways, such as non-myelinated afferent axons from nociceptors. Laser irradiation suppresses the excitation of these fibers in the afferent sensory pathway.
6. Increased nerve cell action potentials: Healthy nerve cells tend to operate at about -70 mV, and fire at about -20 mV. Compromised cell membranes have a lowered threshold as their resting potentials average around this -20 mV range. That means that normal non-noxious activities produce pain. Laser therapy can help restore the action potential closer to the normal -70 mV range.
7. Increased release of acetylcholine: By increasing the available acetylcholine, Laser Therapy helps in normalizing nerve signal transmission in the autonomic, somatic and sensory neural pathways.
8. Axonal sprouting and nerve cell regeneration: Several studies have documented the ability of laser therapy to induce axonal sprouting and some nerve regeneration in damaged nerve tissues. Where pain sensation is being magnified due to nerve structure damage, cell regeneration and sprouting may assist in reducing pain.
History of Lasers and Laser Therapy
Light has been recognized as a source of energy and healing since the early days of recorded time. Ancient Greeks, Romans, and Egyptians practiced heliotherapy, or healing by sunlight to treat various ailments.
In the 17th century, Sir Isaac Newton identified the visible spectrum of light when he separated light with a prism.
Foundation of the Laser
Albert Einstein first explained the theory of stimulated emission in 1917, which became the basis of Laser.
He hypothesized that, when the population inversion exists between upper and lower levels among atomic systems, it is possible to realize amplified stimulated emission and the stimulated emission has the same frequency and phase as the incident radiation.
However, it was in the late 1940s and ‘50s that scientists and engineers did extensive work to realize a practical device based on the principle of stimulated emission. Notable scientists who pioneered the work include Charles Townes, Joseph Weber, Alexander Prokhorov and Nikolai G Basov.
Initially, the scientists and engineers were working towards the realization of a MASER (Microwave Amplification by the Stimulated Emission of Radiation), a device that amplified microwaves for its immediate application in microwave communication systems. Townes and the other engineers believed it to be possible to create an optical maser, a device for creating powerful beams of light using higher frequency energy to stimulate what was to become termed the lasing medium.
Despite the pioneering work of Townes and Prokhorov it was left to Theodore Maiman in 1960 to invent the first Laser using ruby as a lasing medium that was stimulated using high energy flashes of intense light.
Laser Therapy Advancements
Microlight Corporation of America received the first FDA 510k clearance for an LLLT device in 2002. They performed a randomized placebo-controlled study for temporary relief of hand and wrist pain associated with Carpal Tunnel Syndrome by the ML830(R) laser. Microlight came in as a PMA because it did not have a predicate, but was changed to a Class 2 because it was not a significant safety risk. The Microlight study showed a relatively small difference between the placebo and device. However, the FDA considered the ML830(R) laser as an alternative to drugs and physical therapy that may work for some people.
Avicenna Laser Technology, Inc. received the first FDA 510k clearance for a LLLT device with a Class IV power level on December 11, 2003. This laser was a 7.5 watt therapy laser, a significant development from Class IIIa (5mW) and Class IIIb (500mW) therapy lasers. Since 2003, a number of companies have received FDA 510k marketing clearance for both Class III and Class IV therapy lasers.
Development of Laser Therapy
Hungarian physician Endre Mester was a pioneer of laser medicine, including the use of low-level laser therapy (LLLT). In 1967, only a few years after the first working laser was invented, he started his experiments with the effects of lasers on skin cancer. He is credited as the discoverer of positive biological effects of low power lasers.
By the end of the 1960’s, Endre Mester was reporting an improved healing of wounds through low-level laser radiation. Since then scientists and doctors have understood more about the nature of light and its positive effects on the body, developing new techniques and devices for use in medicine.