Mitochondria are thought to be a likely site for the initial effects of light, leading to increased ATP production, modulation of reactive oxygen species, and induction of transcription factors. These effects in turn lead to increased cell proliferation and migration (particularly by fibroblasts), modulation in levels of cytokines, growth factors and inflammatory mediators, and increased tissue oxygenation. The most likely candidate within mitochondria for this pathway is the binding of nitric oxide to the iron containing and copper containing redox centers in unit IV of the mitochondrial respiratory chain, known as cytochrome c oxidase.
RLT is similar to other therapies that “stress” the body causing short term controlled increases in oxidative stress, such as Ozone and Hyperbaric. These therapies are believed to produce a shift in overall cell redox potential in the direction of greater oxidation. In turn, the body up-regulates the anti-oxidative pathways.
The results of these biochemical and cellular changes in patients include such benefits as increased healing of chronic wounds, improvements in sports injuries and carpal tunnel syndrome, pain reduction in arthritis and neuropathies, and amelioration of damage after heart attacks, stroke, nerve injury, and retinal toxicity.
Evidence suggests that both energy density and power density are key biological parameters for the effectiveness of laser therapy, and they may both operate with thresholds.
The use of LLLT in patients almost exclusively involves red and NIR light (600- 950 nm) due to the chromophores of Melanin and Hemoglobin with absorption bands less than 600 nm and water at 1150nm.
The use of low levels of visible or near infrared (NIR) light for health benefits has been known for forty years, since the invention of lasers. The real question is not IF they work but HOW they work and if LASERS (coherent light) vs. LED (non coherent light) makes a difference.
Benefits of therapies include: