Though heat production is responsible for some of the response in "target
tissue", most of the effect that one gets with the various types of phototherapy
reported is due to direct photoactivation of cells. I have spent several months
now collecting and reviewing multiple published articles on low level light
therapy - 20-30 years worth - hundreds and hundreds of articles. It most
instances, the light source can be anything - laser, LED, incandescent,
fluorescent - if it is properly filtered/managed to produce the desired
treatment result. We have multiple lasers in our office - excimer, diode, YAG -
and multiple LED based devices - Gentlewaves, Max7, numerous prototypes of our
own construction. The latter devices have been used for everything from wound
healing, to pain relief, to various ophthalmic conditions...

There are all manner of variables, of course, but the response of biologic
cells is amazingly constant to certain wavelengths (red and near IR = most
common active wavelengths - thought, others are also active for various things)
and power levels (typically 1-4 J/cm2, rarely higher levels in the 7-9 J/cm2 may
give added benefit). There is almost no added benefit to laser light sources
over LED, for instance, except for higher power levels which can translate into
shorter treatment times and - maybe - deeper penetration in some tissue.
Polarized light sources come close to matching laser sources in many instances.
There seems to be little benefit between pulsed or continuous wave sources in
most applications. Multiple different wavelengths may be of benefit in some
applications.

We can assert these things about photobiomodulation (the most proper term for
what we are attempting to do) - with the proper light therapy "code" we can get:

*Mitochondrial activation
*Non-mitochondrial activation (cell walls, cytoplasm)

*Some common photoacceptor molecules are: nnHemoglobin, nMyoglobin,
nCytochrome c oxidase, nNADH-dehydrogenase

*Gene UP-regulation (nIntegrins, nidogens, laminin, actin, kinesin motor
proteins, semaphorins/collapsins)

*Gene DOWN-regulation (nCytokine receptors: nInterleukin-1, interleukin-10,
macrophage inflammatory protein-2; nProapoptotic proteins:nApoptosis activator
Harikiri (HRK), programmed cell death1 protein precursor (PDCD-1; PD-1),
receptor-interacting protein (RIP)

n*ATP production can be increased/decreased

n*DNA/RNA production can be increased/decreased
n*Cells "re-set" genetically to be more "normal"
n*Cell proliferation can be increased/decreased
n*Cell adhesiveness can be increased/decreased
n*Pathogens can be killed
n*Bone growth can be stimulated
*Pain can be reduced (as effective as NSAIDS)
n*MMP enzymes can be down-regulated
*nFibroblasts can be increased - numbers and activity
n*ECM can be increased
n*Neuro-protection and neuro-regeneration
n*Bioregulatory/hormonal systems can be modulated
n*Mental states/conditions can be modulated
n*Protection against toxins - chemical, radiation
n*Blood flow can be increased
n*Tissue swelling can be reduced
*nVEGF can be down-regulated
n*Collagen and pro-collagen promoted
n*Angiogenesis promoted
n*Macrophage activity can be increased/decreased
n*Lymphocvte activity can be increased/decreased
n*Apoptosis decreased
n*Production of Growth Factors promoted - such as nKGF (Keratinocyte), nTGF
(Transforming), nPDGF (Platelet-derived)

nWhat does this mean? Proven.
n*Significant reductions in healing times (50-80%)
n*Significant improvement in wound strength (nSoft tissue and bone)
n*Improved bone to implant adhesion
n*Significant reductions in pain (as effective as oral NSAIDs)
n*Significant temporal effects (up to months)
When one hears claims about the superiority of one particular device, one
needs to be very careful about falling for sales hype. One can achieve similar
therapeutic results with a wide array of devices, I believe. The wattage of a
particular laser is really a "so what" and often translates into nothing more
than "I've got a bigger you-know-what than you do!" Unless, a company can
produce real, supportive research data that is independly verified, then all
claims are suspect.

The photobio effect of low level light is tremendously powerful if it is the
right "dose" (wavelength, power, etc.). One FDA approved device, for instance,
the Gentlewaves by Light Bioscience, is a double panel of 590nm yellow LEDs. It
emits about 0.1J/cm2 (!) in its 40 second treatment time. 8 of these treatments
over one month will result in visible wrinkle reduction and obvious skin
rejuvenation. The effect continues for 6-12 months! This treatment is proven to
reduce inflammation (the MMP cascade), reduce collagenase production (what gives
us wrinkles), and switches on new collagen production. We have had one in my
office for nearly three years and it is very real

Hopefully some of this will be of help to a few out there. I just don't know
how productive it is to endlessly debate the power output or superiority of some
particular "laser" device. ...And, we are not just after heat generation -
therefore, do not need microwave or u/s devices!

Robert S. Dotson, M.D.
Refractive Surgery Center
Oak Ridge, Tennessee
USA