Phototherapy

What is phototherapy?

Phototherapy is a medical field where patients are treated with light illumination thus harnessing the biological effects of low-level
narrow-band (LLNB) light. Today, phototherapy is used worldwide to treat ulcers, musculoskeletal injury, pain and inflammation.

Optics.

Phototherapy initially involved soft lasers with output powers of less than 1 mW. Over the years technology has improved and powers have
increased. Today treatments are performed with devices having output powers between 4-40 mW. Treatment times, however, have shortened,
as powers have increased and the light exposure delivered to the treatment site are usually 1-4 J/cm2. The characteristics of light illumination; coherency
and monochromaticity, have been examined in detail and it is clear that coherency is are not crucial because it degrades rapidly by scattering as
the beam passes through the tissue. Monochromaticity also is not crucial however, is vital as investigators have repeatedly shown that effects observed with narrow-band stimulation are absent with broad spectrum light. The optical "window" lies in visible to
infra-red portion of the spectrum, extending from 600 nm to 1300 nm and including most of the products used in phototherapy. In particular, 660 nm have been widely used in wound healing while 940 is effective in pain relief.

Biological effects of LLNB light illumination.

In recent years, phototherapy has been a subject for credible and rigorous scientific research both in the laboratory and in the clinic in order to delineate the mechanisms
and clinical applications of phototherapy. The basic tenet of phototherapy is that LLNB light illumination has a wavelength and intensity-dependent capability to alter cellular behavior in the absence of significant heating thereby exerting various effects
at the biochemical, cellular histological and functional levels. The scientific rationale behind phototherapy relies on the fact that ample published scientific work has found clear evidence that LLNB light alters cellular processes. These include protein synthesis,
cell growth and differentiation, cell motility, membrane potential and binding affinities, neurotransmitter release and ATP synthesis etc. The mitochondria, which is the main
subcellular organelle responsible for the cell's energy production, exhibit frequency-dependent
action spectra and many scientist feel that the mitochondria is at the base of the
phototherapeutic effects of LLNB light. The most intensively investigated clinical application
of phototherapy is the acceleration of cutaneous and mucosal wound healing.

Safety.

The power used in phototherapy is by definition to low to cause tissue damage and
there have been no reports on adverse effects of LLNB illumination. However, retinal
hazard is a concern and avoidance of looking directly at the beam source seem prudent.