Introduction to Photobiomodulation


Low level laser (light) therapy (LLLT) or photobiomodulation employs visible (generally red) or near-infrared light generated from a flash lamp, or light emitting diode (LED) system to treat a range of conditions that included injuries, pathologies and conditions. Photobiomodulation has been proven to be effective for stimulation and healing, and to promote tissue regeneration and pain relief. 

Red and near-infrared light is a narrow spectral between 600nm – 1000nm. The fluence (energy density) used is generally between 1 and 20 J/cm2 while the irradiance (power density) can vary widely depending on the actual light source and spot size; values from 5 to 50 mW/cm2 are common for stimulation and healing. Higher dosage will be used for pain relief. 

Photobiomodulation is efficacious to promote tissue regeneration, reduce swelling and inflammation and relieve pain. Within a matter of a few seconds light is delivered deep inside tissue, and triggers biochemical responses at the molecular level.

By definition, photobiomodulation is not a thermal mechanism - it does not create heat. That simple distinction differentiates it from other light therapies that attempts to  generate different responses. The photochemical effect elicited by photobiomodulation is comparable to photosynthesis in plants. 

Red and near-infrared light is absorbed by cytochrome c oxidase, or CCO, a photosensitive enzyme found within the mitochondria. The mitochondria is the energy-making machine that sits at the core of our cells. The CCO absorbs the light, converts it to energy that in turn triggers a biochemical response that enhances the efficiency of the cell.

Biphasic Dose Response 

More is not better. 

As we are gaining a better understanding of how photobiomodulation operates at the cellular level, we can explain how a little light may be beneficial and a lot of light might be impotent or harmful.