The History and Uses of Phototherapy
We are still on the threshold of fully understanding the complex relationship between light and life, but we can now say emphatically, that the function of our entire metabolism is dependent on light.
–Fritz Albert Popp
Inspired by the discoveries of the biological pathways of light described in the previous chapter, light medicine (often called phototherapy) has been in full expansion since the beginning of the 21st century.
There are two main categories of phototherapy:
• First there is the type that makes use of the natural interactions that light already has with our bodies: endogenous phototherapy. It includes therapies based on photobiomodulation (the interaction of light and cell mitochondria) and chronobiology (the interaction of light and circadian rhythms). Endogenous phototherapy usually has regenerative properties and tends to reestablish natural order in a non-invasive way.
• Then there are therapies that use light as a catalyst in custom-made biological processes: synthetic phototherapy. They arise from our increasing understanding of the biochemistry of chromophores, those molecules capable of absorbing or emitting light, enabling us to make use of them in completely new ways. These therapies are generally more invasive and radical and are used for more aggressive interventions: for example dynamic phototherapy excels in the destruction of cancer cells, and ultraviolet phototherapy can heal certain infections and serious diseases through the sterilization of pathogens.
The Tools of Light Medicine
Lasers generate light with very precise wavelengths and almost no divergence, allowing for a very fine and intense focal point. Several types of medical lasers are now in use including:
• Ablative lasers: often in the infrared range and very powerful, they can vaporize layers of the epidermis and are used in dermatology. Other types emit green light to vaporise vascularized tissue (since red blood best absorbs green light), used for tumour excision.
• Fractional lasers: their rays are fractured into tiny micro-beams making it possible to treat skin without harm. Used in aesthetic dermatology.
• Pulsed lasers: emit light in very intense but very short bursts in the range of a nanosecond (10-9 s) to a femtosecond (10-15 s). They are used as scalpels in surgery.
• Excimer (or exiplex) lasers: produce ultraviolet light and are used in the treatment of psoriasis and vitiligo.
• Laser diodes: low intensity semiconductor lasers that are more compact and economical than other types of lasers. Used for photobiomodulation to reach specific spots in deep tissue.
Intense Pulsed Light (IPL)
Flashing lamps, fitted with coloured filters and emitting several powerful pulses per second, are increasingly used in dermatology and aesthetic medicine. The best ones have an integrated cooling system to improve comfort.
These can replace lasers in certain applications, particularly in photobiomodulation. Medical LEDs come in a wide variety of strengths and optical beam widths. Different colours are used for different purposes: infrared and red for photobiomodulation, amber for aesthetics, green and blue for acne and chronobiology, ultraviolet in dentistry and for sterilization.
These are mostly used in the treatment of depression and in other chronobiological applications.
Photobiomodulation intervenes at the very source of the cell’s regenerative abilities. All ancient peoples, as well as the light therapy pioneers of the last century, used it intuitively. But it was not until the invention of the laser in the 1960s that its use in medicine first began, followed by a surge in its popularity as a result of the discoveries of Professor Tiina Karu in the 1990s.
Given the fundamental nature of the cellular processes involved in photobiomodulation, it is not surprising that the scope of possible applications keeps expanding. These applications include:
• Repair and regeneration of tissues by the bio-stimulation of cellular metabolism (for wounds, muscle trauma, hair loss, macular degeneration, regeneration of internal organs such as the heart, liver and kidneys)
• Stimulation of the immune system resulting in a lowering of inflammation (for dermatitis, eczema, asthma, arthritis) Pain relief (for post-operative pain, dental treatments, mucositis)
• Neurological effects, both physiological and cognitive (for brain trauma, strokes, depression, memory problems, dementia)
A Well-Kept Secret?
Photobiomodulation is already being applied by many specialists. High performance athletes (for example in the Tour de France) and the military have utilized it for several years now to treat muscle trauma or tendinitis, and astronauts have been using it longer still. Why then, apart from a few exceptions in sports medicine, would photobiomodulation not be more prevalent?
This can be partly explained by the fact that many of the applications of photobiomodulation are still experimental. Even if numerous clinical studies have shown convincing results, protocols still need to be established and the necessary clinical experience acquired before it can be put to general use.
It will therefore probably take a few more years before the remarkable treatments of photobiomodulation become readily available for all. Even after purely technical issues have been resolved, inertia in the medical system delays the practice of treatments that are radically different from those in common use.
The implementation of photobiomodulation varies greatly from one country to another. Russia is often at the forefront in this field. There phototherapy treatments are relatively common, including innovative applications such as those used for the prevention of heart problems (angina, cardiac arrest, and others).
In the U.S. some devices have already met the strict rules of the Food and Drug Administration (FDA). The first one, in 2002, was designed to treat carpal tunnel syndrome. In 2008 the World Health Organization endorsed photobiomodulation for the treatment of cervical pain. And in 2010 the American Physical Therapy Association recommended it for the treatment of injuries to the Achilles tendon.
Slowly but surely, photobiomodulation is being integrated into our health habits.