LLLT, lllt, laser therapy - biostimulation
The Low Level Laser Therapy -
LLLT Internet Guide

Internet discussion about treatment with LED- vs laser light.

During the spring, summer and autumn 1999, there was an intense debate about the difference in medical effects from treatment with light emitting diodes versus lasers. I collected the different contributions and structurated them to avoid doublets etc. I have tried to make the debate as interesting as possible.
Lars Hode


James Carrol wrote:

Your argument for laser being better than LED's makes sense. However my experience is the LED products we make work brilliantly.

                 I wish your statements on the potential role of LED's was more generous. Your book reads like an attack on LED's and leaves the reader with the sense that LED products are almost of no value and a rip-off.

                 I have been in this trade for 11 years. We have made a variety of laser and LED probes in that time.I have over 1,000 customers that I have dealt with personally, many of which bought LED only probes from me and have come back for more, some I judge to be remarkable practitioners of their profession (mostly physio's). They find them excellent, buy more and refer friends and colleagues to us.

                 My wife is an osteopath and runs a clinic next door to my office. She uses a 69 LED cluster probe and she can detect an immediate change in tissue texture or a reduction in muscle spasm. Every week I get feedback from customers on the results they have been getting.

WHAT ABOUT THE LASER Vs LED RESEARCH

My concern about studies comparing laser and LED's is that probably none of the researchers really measure the spot sizes of the devices they are trying and are not comparing like for like power density.

                 Also even if laser is better, do not dismiss the LED which when it comes to wound healing cluster probes is a much more affordable device than a cluster of lasers. (69 x laser cluster would be quite pricey!). Maybe LEDs just needs to be used longer

BOTTOM LINE

I would not be surprised to find out that in a true like for like LED vs LASER study that laser had the edge on LED or that LED needed a higher dose, however I am not going to withdraw our LED products until I can offer my customers something that performs as well as our LED cluster probes for a similar price because they work brilliantly for the money. We will have a laser cluster probably around the end of this year but will keep the LED ones too. One of the problems with LED's is it is easy to make cheap bad systems and get away with it.

Lars Hode wrote:

Hello James. As you know, I and Jan never questioned that LED's are working. That is not the point. But show me ONE investigation with the conclusion that LED's give better effect than laser. Or, show me ONE investigation showing that LED's are as good as lasers. We can show you a bunch of publications of the contrary. Even some with negative effects from LED's. Further, as we both know that the main part of the high price of therapy instruments is due to small number production and heavy marketing costs - and NOT due to high tech or high laser diode costs, you could just as well chose lasers instead of LED's. It would not be more expensive (maybe marginally) and your customers would get even better results.

                 And the best of all - you could say that "this is a therapeutic laser". If you sell LED's and say to people that this is a laser, and you refer to laser literature, then you are a liar and a cheat! Further, on page 27 in the latest book of Tiina Karu, you can see that wide band light added to coherent light gives a reduction of the biologic effect of the light, compared to coherent light alone. So I see no reason to follow Costas Diamantopolous unscrupulous road. I know how easy it is to power and mount LED's compare to laser diodes, but I assure you, I would never go that way "for a few dollars more" ...

                 The first time I met Costas was in an exhibition at the Stockholm Sheraton, 1983, in a booth with the banner text: "The new laser technique". I looked at the device (Biotherapy III with a single red LED probe) and said to him:  Why do you write “the new laser technique” when you dont use a laser? He said to me:  On what grounds do you claim that lasers should have better effect than LED's?  I said that I dont know, but I think it is wrong to sell lasers without lasers. He then removed the banner, but in his marketing material started to say that LED's are a further development of the laser!

LED's are OK for me as long as the sellers of LED instrumentd don't refer to laser literature. N.B. I don't mean that you do so, I speak in general terms only. 

James Carroll wrote:

Hi Lars. I'm not arguing that it is BETTER, only that it should not get such a rough ride in your book

                 There are plenty of negative studies on laser too but as you often say, it's all in the parameters.

(See my argument re bad LED light measurement in original message). My argument was from 11 years of experience, not a large body of controlled trials. We both know that the research on LED devices in vivo is tiny in comparison so there is relatively little information to draw on to prove the argument either way. 

                 I enclose abstracts from 5 studies which do go some way to support my case.

1)   Baxter had a trial published in Laser Therapy 1998 V10 No3 on four patients using an Omega 31 cluster (mixed laser and LED), 499mW of of LED, 25mW of laser, total dosage of 4.2J/Cm2, that is 4.7% 820nm laser 95.3% LED. The results were positive.

     are you going to tell me that it was the 4.7% laser that healed those wounds and reduced that pain ?

2)   Gupta et al, Journal Dermatol Treat (1997) 8: 103-108, Low energy photon therapy treatment of leg ulcers, 660 and 880nm LED only cluster probe, 9 patients, 15 non healing venous ulcers. The results were positive

3)   Robinson et al, The use of Low Level Laser Therapy in diabetic and other ulcerations, Journal British Podiatric Medicine 1991 October 186 - 189.  7 Patients with non healing ulcers (4 of them diabetic). Same cluster probe used by Baxter (see above). The results were positive

4)   Franks et al. Encouraging chronic wounds to heal with the use of low-level laser therapy

Abstract from 8th European Conference on Advances in Wound Management. 10 patients non healing venous ulcers. Same cluster probe used by Baxter (see above). The results were positive

5)   Jilliane James. Primary Care. Care Vol 4 10 1997 18 - 20. Laser Therapy on trial.  6 Patients non healing wounds. Same cluster probe used by Baxter (see above). The results were positive

                 So how does that explain the results from the trials mentioned above? What wavelengths was karu referring to when she said that ? I have lost my copy of her book. Multiple wavelength cluster probes tend to use red and IR light and not full spectrum light

Also, the production price is clearly lower for the LED probe:

1)   Even if the smallest laser was GBP 10 more than an LED that would add GBP690  to change our 69 cluster to 69 lasers and manufacturers do not purchase and install materials for free, you would expect a margin to be added to that too. Lets say a total extra cost of GBP 1,000 (1,600 US$)

                 2)   In the UK the use of laser is regulated and particularly in the NHS hospitals often require dedicated treatment rooms to be set up this is not good for bed ridden patients

I hope I have made my reply good enough for you to shift your position on LED's to something like:

"LED's seem to work on wounds and like laser there have been some negative studies too. The clinical research using LED is too small to make comparisons with laser, certainly not enough to prove the argument either way"

I appreciate that you are playing the role of Robin Hood and saving us from the the scurge of the baddies who lie but most of them have gone now (I know of only one product that proports to sell laser but fits a feeble low powered LED instead and that company is in Australia)

Philip Gable wrote:

Having read the last few postings a consensus appears to be that LED  does have a role that appears to be under estimated.

                 A personal opinion is that it is only worthwhile in cluster format and then only with a total power output that is significant and satisfactory to be able to supply in the order of 1W total output as a minimum and to an area of at least 10 cm2.  Less than this is impractical for the application.

                 Though anecdotal but it seems to take around 2x the incident dose of LED to produce the effect of the Laser probe and then to a much shallower depth of penetration. It is an area of need for research. Without doubt - wounds, skin conditions and superficial soft tissue lesions - particularly those that are acute seem to be the most suited.

                 There is also a strong hint that pain is altered in a similar way and to a similar degree by LED as LLLT - this is most likely via the opioid systemand would seem logical  in terms of the area of tissue exposed and thepotential for the effect to be made.

                 Perhaps the simplest way is the repetition of Laakso's 1995 study on endogenous opiates but using a comparative between LED and LLLT and measuring the serotonin levels produced by comparatively similar incident doses. So which lab wants to do it??? Remember - some of us contribute with theory but have not the resources or time to do the grunt work.

James Carroll wrote:

What about possible accumulated power density of cluster probes ?

                 THOR cluster probes have the LEDs VERY close together.  69 LEDs or 104 LEDs crammed together typically less than 2.5 mm apart, each LED having 6 or more LEDs in less than 2.5 mm from eachother.  Phil Gable's 104 cluster is 2 Watts in total !

The accumulated scattered of light must add up to something deep down ?

                 BUT light is funny stuff, it does not always work the way you think it does

Its not just a particle, it's not just a wave beware the simple models/concepts of the mind

Peter Atkins replied:

Well James we have spoken about that before, and you didn't really believe my train of thought.

I believe there are two types of penetration that can be measured.  Direct penetration, and depth of effect.  To measure direct penetration into tissue I use a (approx) 2mW IR sensor, if it is triggered at a depth of one inch, then I know that at least 2mW of IR energy has penetrated to that depth.  Depth of effect I cannot measure, but Kert and Rose in their book Low Level Laser Therapy, mention a study that they (I believe) conducted that measured the reaction of the cells, and they found that if an amount of 16 joules was input at the surface, then a reaction occured in the cells at a depth of 10cm.  I don't think that photons of energy could penetrate to that depth.

                 If the photons of energy cause a reaction in a cell, and that cell released hormones, electrical impulses and other chemicals, that should trigger the adjoining cell to have some reaction, which should trigger the next cell etc etc.  Is this viable?   

I don't know, it is waaaay too deep for my knowledge.  Please the physicist on the list, can you join in and give us your scientific point of view.

James Carroll wrote:

Seeing as someone emailed me direct for this info I thought I stick it on the list for all a couple of the relevent paragraphs of Laakso's 1995 study:

Published Laser Therapy 1994 6: 133-142

Laakso et al

Royal Brisbane hospital, Australia

PLASMA ACTH AND § -ENDORPHIN LEVELS IN RESPONSE TO LOW LEVEL LASER THERAPY (LLLT) FOR MYOFASCIAL TRIGGER POINTS

ABSTRACT

The mechanism by which laser phototherapy (Low Level Laser Therapy - LLLT) induces analgesia in the treatment of chronic pain is not understood. To investigate a possible role for opioids in this treatment,, a double-blind, placebo-controlled study was designed to compare the effect of two dosages (1 J/cm2 and 5 J/cm2) of an infrared (JR) laser (820 nm), a visible red laser (670 nm) and a near-monochromatic light emitting device (660 nm, 30 nm bandwidth) on trigger points. Fifty-six consenting subjects with chronic pain conditions exhibiting myofascial trigger points in the neck and upper trunk region underwent six experimental sessions over a two week period. Blood samples were withdrawn before and after treatment on three of six appointments. Plasma was assayed for § -ENDORPHIN (radioimmunoassay, RIA) and adrenocoracotropic hormone (ACTH - two-site immunoradiometric assay, IRMA) to assess opioid response. ACTH was shown to have a cumulative response to treatment with 1 J/cm2 infrared laser (p < 0.001) and 5 J/cm2 red laser (p < 0.05) responding significantly.. § -endorphin was noted to be significantly elevated between days one and four (p < 0.05) in subjects who received IR (5 J/cm2) laser. Results indicated that the analgesic response to phototherapy may be mediated through hormona/opioid mechanisms, and that responses to LLLT are dose and wavelength dependent. A mechanism by which peripheral stimulation using LLLT may elicit activity in the central pathways is proposed.

EFFECT OF POWER OUTPUT AND ENERGY DENSITY

To understand the results of this study further, one must understand that LLLT conforms to the Arndt-Schultz principle which implies that very low doses of laser have no effect on cells, low doses stimulate cell processes, high doses inhibit cell processes, and that even higher doses result in photodynamic damage of cells. The results of this study appear to confirm this notion. That is, there may not have been sufficient photonic energy to stimulate responses using 660 nm near-monochromatic red light or low dose 670 nm (red) laser. This may explain why the Pearson correlation co-efficient between ACTH and ,B-endorphin levels for near-monochromatic red light was less than half that observed for the remaining treatment groups (Table 3). Power output may have been the critical factor in this study and future studies should control for this.

snip snip

CONCLUSIONS

This study has confirmed that responses to LLLT are dose, power output and wavelength-dependent. The fact that low dose (1 J/cm2) IR laser (820 nm) and high dose (5 J/cm2) red laser (670 nm) resulted in a cumulative pre-treatment increase in ACTH and high dose (5 J/cm2) IR laser resulted in increases in plasma § -endorphin levels over the duration of the study suggests that localised, peripheral phototherapy of trigger points can induce cumulative activation of central hormonal/opioid pathways capable of regulating immune function. This was likely to have occurred through a link between mast cell degranulation, or stimulation of cytokine-mediated CRH release by altering macrophage responsiveness. As high dose (5 J/cm2) LLLT resulted in potentiation of overall levels of § -endorphin and ACTH, it is suggested that the therapeutic window of doses for LLLT treatment of trigger points could be extended to include 5 J/cm2. This would need to be validated by conducting adjunctive studies on subjective pain responses. It is acknowledged that power density may have resulted in the fact that neither low dose nor high dose near-monochromatic red light (660 nm) was found to be capable of eliciting significant changes in blood biochemistry. The suggestion that the laser is a necessary requirement for phototherapy of trigger points remains to be confirmed.

Jan Tunér wrote:

Interesting discussion. Will be back. This is an important issue. A concensus statement would be of help for two reasons: to get rid of the guys trying to sell LED:s as lasers and to get rid of a possible conflict within the LLLT comunity itself. LED works and LLLT works, but probably differently. And the scientific foundation for LLLT is superior. So far.

Peter Atkins wrote:

Depth of effect I cannot measure, but Kert and Rose in their book Low Level Laser Therapy, mention a study that they (I believe) conducted that measured the reaction of the cells, and they found that if an amount of 16 joules was input at the surface, then a reaction occured in the cells at a depth of 10cm.  I don't think that photons of energy could penetrate to that depth.

Karen Carroll wrote:

The most interesting thing I have seen on penetration is the radiographic phantom model assessment of penetration depths by Oshiro (LT, Sept 1996, Vol 8.3) - this model suggested penetration into the nerve root exits and some penetration into the spinal canal - certainly in the order of several cm.

                 They  also say in the same paper that the incident and penetrating light energy need not be coherent to trigger a response as a single photon is capable of doing so in theory.  They suggest high densities of photons are what is needed to deliver clinically useful doses of photons at depth. This is clearly what a well powered, high photon density cluster probe of LED's can do in my opinion.

Peter Atkins:  If the photons of energy cause a reaction in a cell, and that cell released hormones, electrical impulses and other chemicals, that should trigger the adjoining cell to have some reaction, which should trigger the next cell etc etc.  Is this viable?

Karen:  I am not sure a "cascade" type reaction will necessarily happen, but changing the intra-cellular environment of one cell will affect the extra-cellular environment of the surrounding cells - which may then trigger a response. However, I am sure that with a reasonable power density probe of appropriate wavelength for the area being treated of LED  or Laser will send bundles of photons into and around the target tissue which will affect a number of cells of different types - which will result in a change in the tissue being treated.

Philip Gable wrote:

I see some debate on both interpretations of the information available and the theoretical models proposed - See Oshiro as Karen Commented below - Peter you are referring to the Diagram on P28 of Kert and Rose which is a "schmatic model representation" of their ideas / thoughts.

The "single photon"  theory which stimulates or catalyses the reaction in the tissue to cause a "depth of effect" far greater than the actual depth of penetration of the photons them selves. Oshiro's paper builds on this idea as Karen eluded to..

                 In LEDs, this "Depth of Effect" will (I feel) be less as the incident power density is less and the penetration less - i.e. it doesn't pack the same punch once its past the initial few millimenters. Even with the increased number of sources as occurs in a cluster or as Karen put it "... in a well powered, high photon density cluster".  But the number of photons arriving in a dynamic living tissue will be different to that  which occurs in a vive-section which Oshiro studied.  Without the presence of the blood and body fluid [and even for that matter the "Qi or Chi" the energy of life] to interact and take some of this incoming Energy to absorb or take it away, the living tissue will always have a lower penetration to that of the lab test section.  What Oshiro does show though is that a LLLT source can penetrate quite a long way - whats now needed is to see if it is the same with a cluster and then move onto the live tissue testing - perhaps James and Peter can put their  power meters behind a hand or other appendage ( .. read finger there ) with probe and a cluster  source and tell us the differences - no cheating boys!!

                 It is this "cascade type reaction"  that is fundamental to the transmission of the LLLT effect.  The debate is whether the LED Cluster can do the same as the true LLLT probe to the same depth and with the same biostimulatory effect  for the same or a better price.

                 The "cascade type reaction" is effectively what Oshiro refers to in his fruity lecture on "APPLES" .  Interestingly enough his model is that of a simplified expansive action that radiates out equally in all direction from the incident tissue.  This contrasts with Kert and Rose model  which is an implosive reducing effect toward a single final point of penetration in "depth of effect"; -  Perhaps an inverted elongated cone rather than an apple.

                 My own theory is that of a combination  of the two - which provides something akin to a modern design variation of the traditional light globe with the bulb hanging att eh greatest depth- but add an exaggerated washer to the base that represents the initial few millimeters of target tissue.

                 Regardless to what depth the photon penetrates,  Kenrick Smith's reference to the "First Law of Photo Chemistry", must apply - namely "that light must be absorbed before photochemistry can occur". hence his interpretation of 2 studies on the same condition PHN that gave the opposite effects

                 E.g. The Action Spectrum for Post Therapeutic Neuralgia (PTN) [Walker, 1987] found 633nm ineffective, [Moore, 1989 ] found 830 nm very effective for reducing such pain. Possibly due to 633 nm having poor penetration thru superficial skin and not reaching the target tissues.

                 Mr Smith also outlines in his 1990 paper at the Osaka international conference "Light and life - the photobiological basis of the therapeutic use of radiation from lasers" the 2 key aspects of the 4 methods of  the "catalystic effect" and differentiates between the visible and IR regions - perhaps this may asist in why some of us (like me) anecdotally feel that the LED does not penetrate nor provide a "depth of effect" as well as the LLLT probe - yet holds its own on the superficial conditions.  Namely 

1. Radiation production of the substrate.

2. Irradiation of the enzyme-substrate complex.

 

3. Direct enzyme activation: (Hug 1991). By simulating a conformational change

- in the enzyme molecule itself

- in an attached photochromic inhibitor

- by photochemically splitting an inhibitor form the enzyme.

4. Induce enzyme synthesis. By gene activation the enzyme is produced. Eg. the mechanism for wound healing (Saperia et al 1986) Laser irradiation at 633 nm stimulates collagen synthesis in cutaneous wounds by enhancing the synthesis of Type I and Type II procollagen mRNA levels.

 

Of these 4 mechanisms the first two do not result in amplification as one absorbed photon is required for each photochemical event - thus high intensity radiation is needed.

For the second two, amplification occurs with more chemical change than the number of photons absorbed and these are consequently candidates for a photobiological basis for LLLT (in the visible region).

                 Infrared radiation absorption results in molecular rotations and vibrations and would not be expected to cause molecular chemical changes. (though reactions may be induced by heating). So how then can infrared (eg 904 nm) and visible (633 nm) radiation laser produce similar clinical responses?

Karu (1988, 1989) has proposed a chain of molecular events to explain the biostimulation effect of LLLT which Smith then modifies to give us our current thinking on this - at least till Lutz Wilden brought in wave particle concepts!!

                 This also backs up the initial work of Kubasova et al 1984 (Lasers in Surgery and Medicine) who first suggested that cell - to - cell contacts were strengthened due to the effect of LLLT on the cell membrane, this  gives the "catalytic effect" Peter raised and Karen questioned above.

                 The explanation of this was then extrapolated by Fenyš  (the intial co-worker with Kubasova in the 1988 article on "the investigations of biological effects of polarised light" in Photochemistry and Photobilology Journal ) and led to the conclusion that the polarisation of the lipid bilayer results which in turn explains the effects from the cellular contact or cell-to-cell level.

Peter Atkins wrote:

When I left Oz five years ago I was also very focussed on and committed to laser, this was partly due to the manufacturers that were trying to pass very low powered LED's off as Lasers.   Having worked in Europe with good quality LED's systems and seen the results, I have changed my mind.  There is definite places for both LED's and Lasers in specific applications, often the best is obtained when using a combination of probes, wavelengths power outputs and PD's.  Using a combination of outputs allows you to treat the whole cell and to have energy absorbed throughout a greater range of depth than using a single probe.

Philip Gable wrote: 

A personal opinion is that it is only worthwhile in cluster format and then only  with a total power output that is significant and satisfactory to be able to supply in the order of 1W total output as a minimum and to an area of at least 10 cm2.  Less than this is impractical for the application.

Peter Atkins:  Don't quite totally agree with that.  I would say any wound healing application, often a single point probe is needed to access inside a bed sore or ulcer for instance.  Yes it is great, quick, to treat the whole wound with a cluster probe, but it is also very effective to treat all around the edge of the wound with a single point probe.  Yes you could do both of these with a single point Laser probe, but the spot size would be much smaller than a LED probe thus taking more time.

                 Totally agree hence the probable consensus; TO achieve the same effect as the point probe of a true LLLT via a true laser an LED will be required for a greater time and Incident power density -  and raerely can I see the value of them in sole situation where the true laser probe will have a greater efficiency and effect.

Phil: Though anecdotal but it seems to take around 2x the incident dose of LED to produce the effect of the Laser probe and then to a much shallower depth of penetration.

Peter Atkins:  Not for superficial applications, 4J per cmsq, is 4J per cmsq.  Yes if you are trying to treat to some depth, because of the lack of penetration you will have to increase treatment times.To be absolutesly certain it has been debrided then you may be ok but if it has any slough or you are treating an injury (not a  wound) and there is skin epidermis etc then I feel the above is still applicable as a rule of thumb.

Phil: It is an area of need for research.

Peter Atkins:  Yes..  Even something simple like two probes and a control, treating an open wound situation.  One probe a 660nm LED at 10mW  and the other probe a 660nm Laser diode at 10mW. Same treatment times, same parameters.  Then we still get into a problem of the difference in PD.

Phil:  With out doubt - wounds, skin conditions and superficial soft tissue lesions - particularly those that are >acute seem to be the most suited.

Peter Jenkins wrote:

Hello to all from another antipodean. I've been following the Laser v LED banter with interest, and I'd like to throw my thoughts into the ring...

After a similar discussion with Jan TunÉr a couple of months ago, I developed the following statement:

" There is currently little doubt that the light emitted by LEDs (non-coherent, monochromatic light; spontaneous emission) is effective in generating a biomodulatory response within living tissue, and therefore has a therapeutic role if used correctly. Tiina Karu (1998:   The Science of Low-Power Laser Therapy) states that "...the coherence of light is of no importance in low-power laser clinical effects" and "[t]he primary difference between lasers and LEDs is that the laser's coherent beam produces "speckles" of relatively high power density which can cause local heating of inhomogeneous tissues".

                 However, to date, the majority of published research has been conducted using LASERs (coherent, monochromatic light, stimulated emission). Due to the differing properties of LED and LASER generated light, and the relative lack of LED-specific research, it is misleading to suggest that meaningful information about practical LED therapy can be simply derived from LASER therapy research. Until more research is carried out and the mechanisms of photobiomodulation are better understood, this will remain the case."

                 I think this adequately sums up the current situation, and is probably only restating the concensus that has seemingly been reached through this forum:  that both LEDs and LASERs work, but more research must be carried out with LEDs. Any LED research will only ever further our understanding of the mechanisms of photobiomodulation overall, which has to be worthwhile.

                 Ideally - and this applies to our own cluster probes as well - I'd like to see multi-wavelength cluster probes (whether they be LASER or LED) dropped in favour of clusters that only emit one wavelength at a time. A combination of laser diode and LEDs could be used (ie. a combination of power densities but at the same wavelength), to achieve a more homogeneous distribution of photons through the incident tissue. The laser will still produce it speckles (the actual effects of which is not yet fully understood) and so keep the laser-philes happy, and the LEDs will get a look in as well.

                 Karu (1998, pp59-60) has shown (albeit in vitro) that using different wavelengths (760 nm and 633 nm) in succession can produce very different effects within the cell, depending upon the order in which each is applied, due to the interaction of these wavelengths with different photoreceptors.

                 In a multi-wavelength probe, especially one with lasers and LEDs, there are a number of different parameters that can affect the outcome of irradiation (2 or more power densities, different wavelengths, coherent and non-coherent light, laser speckles, pulsing frequencies, etc.). I challenge anyone to say that, at this stage in our understanding of photobiomodulation, they have determined the optimal combination of these numerous and variable parameters.

                 For manufacturers there are, of course, commercial realities to face, and so there will be multi-wavelength cluster on the market for some time to come. However, each manufacturer should at least make some statement to the effect that the laser v LED debate is currently unsettled, and that the effects of the particular combination of wavelengths used in their equipment is by no means optimal or fully understood.

                 Anecdotal evidence of effectiveness is fine to a limited degree, but let's gain a better understanding of the mechanisms by which each variable ( eg. coherent v non-coherent) affects the biological system in vitro and in vivo, before adding too many variables into the equation. Once we fully understand the individual mechanisms, we can look at combining these mechanisms to see how each combination affects the overall biomodulatory response, and how then to apply the various responses for optimal therapeutic benefit.

It will take time, and research funding is always hard to come by, but we are talking about a valid area of scientific investigation and so the same methodologies and controls should apply. The results should be worth the effort.

                 I encourage anyone following the discussion to date to also join in - the more the merrier, so they say!

Peter Jenkins:  

Ideally - and this applies to our own cluster probes as well - I'd like to see multi-wavelength cluster probes (whether they be LASER or LED) dropped in favour of clusters that only emit one wavelength at a time. A combination of laser diode and LEDs could be used (ie. a combination of power densities but at the same wavelength), to achieve a more homogeneous distribution of photons through the incident tissue. The laser will still produce it speckles (the actual effects of which is not yet fully understood) and so keep the laser-philes happy, and the LEDs will get a look in as well.

Peter Atkins: 

But if we use a combination of coherent and non-coherent for research then we aren't proving anything other than one of them is working.

   I would prefer to see a coherent light probe of a specific wavelength compared to a non-coherent light probe at the same wavelength and outputpower.  Even go one step further and diffuse the laser beam to the same PD as the LED.

   For treatment I believe a combination of wavelengths is best, then you get absorbtion of a greater area, and as importantly by differing areas within the cell.

Peter Jenkins:  

So keep the laser-philes happy, and the LEDs will get a look in as well.

Peter Atkins:  

Then we are back to confusing and misleading people, in both our cases Peter, our clients.  I believe it is wrong to sell a probe as a "laser probe" if any of the diodes are LED's.

Peter Jenkins:   Karu (1998, pp59-60) has shown (albeit in vitro) that using different wavelengths (760nm and 633nm) in succession can produce very different effects within the cell, depending upon the order in which each is applied, due to the interaction of these wavelengths with different photoreceptors.

Peter Atkins:  Oh no, added confusion, now we not only have to worry about which wavelengths are best in a situation, we now have to worry about in which order we have to use them.   /-:

And I thought life was getting simpler.

Peter Jenkins:   In a multi-wavelength probe, especially one with lasers and LEDs, there are a number of different parameters that can affect the outcome of irradiation (2 or more power densities, different wavelengths, coherent and non-coherent light, laser speckles, pulsing frequencies, etc.).   I challenge anyone to say that, at this stage in our understanding of photobiomodulation, they have determined the optimal combination of these numerous and variable parameters.

Peter Atkins:  No one will put odds on that.  I wish we knew?

Peter Jenkins:   Anecdotal evidence of effectiveness is fine to a limited degree, but let's gain a better understanding of the mechanisms by which each variable ( eg. coherent v non-coherent) affects the biological system in vitro and in vivo, before adding too many variables into the equation.    Once we fully understand the individual mechanisms, we can look at combining these mechanisms to see how each combination affects the overall biomodulatory response, and how then to apply the various responses for optimal therapeutic benefit.

Peter Atkins:  Yes, but which of us manufacturers makes enough money to fund this research?  Unfortunately we are not drug manufacturers, we want to heal our patients and send them away, not provide them with a consumable that they must consume for the rest of their lives, which of course they must buy from us for the 20 years that our patent runs.  And as an added benefit, the consumable sold to them, will cause unwanted side effects that we just happen have another product that will help reduce the symptoms of which they will have to buy from us for the rest of their lives which will in turn cause unwanted side effects, yada yada yaaaa,

Jan TunÉr:   And the scientific foundation for lllt is superior. so far.

Peter Atkins wrote:  

But is that only because more research has been done since lasers have been around a lot longer than LED's?

Karen Carrol:  Well - just to throw another spanner into the works - I think that you will find that the term "Laser Therapy" has been used as a generic term to cover what some have called "photobiomodu-lation" - ie: using light in its various (laser and led) forms to heal. Mary Dysons team have used it as such - I am sorry, I haven't got time to give specific refs - one of the macrophage responsiveness papers, I think and various others.

Its a bit like we use "hoover" as a generic term for vacuuming, although we use various makes of vacuum machines, we still say we will "hoover" the floor.

So - whatever we believe about lasers and leds and their efficacy, the term "laser therapy" is , I think, used as a generic term. Just like 2-3 years ago, the term "laser therapy" , when used on a medline search would come up with 98% articles on surgical lasers - very few articles on LLLT.

Peter Jenkins:   Karu (1998, pp59-60) has shown (albeit in vitro) that using different wavelengths  (760 nm and 633 nm) in succession can produce very different effects within the cell, depending upon the order in which each is applied, due to the interaction of these wavelengths with different photoreceptors.

Karen Carrol:   Yes - but people aren't single cells, how can we know what is the best effect on which cell and in which order ??? We don't. In my 10 years of lecturing on LLLT, to lots of people with many different LLLT/led systems, my conclusion is that most systems work - occasionally even the ones that have no right to!!! - ie: very very low output, etc. People get results out of all sorts of systems - led single and multiple wavelength clusters included ! Leave it to the body - for some reason, it seems to know what to do with this light stuff we stick in it.

    Remember Dyson and Agaiby's work - what had an adverse effect in vitro, when repeated in vivo had no adverse effect (it just had no effect) - in vitro work does not necessarily give the answers for in vivo work. They also had to increase the dose for the best in vivo response in the same study.

    So - I don't worry - the clinical evidence in front of your eyes is what counts on patients - do they get better ??? yes, maybe in 5 years time, we'll be more effective, but I bet there will still be people with systems that are years old, never been serviced, getting some great results !

Peter Atkins:  James or Karen, why do teach using the Laser probe first then the Cluster? Is it for this reason?  In certain Equine conditions I will use the cluster first to relieve all the referred pain, then use the laser on the specific trigger points.

Karen Carrol:  Nope - I teach it because if you are doing the right thing with your probe (!)  and cluster, then the poiints you are treating will be less painful - if you cluster first, you won't be able to find the painful points ! I'm a simple creature really !

                 What most clusters I have used seem to do is help get patients better quicker - which is the point! We don't even understand pain yet ! I agree with PJ's comment in theory - but am still not sure that it will make masses of difference treating patients - we still don't understand how the body's intelligence works, how it decides whether or not to take any notice of the input we give it in the form of light - why it responds sometimes and not others for apparently the same conditions - why some-times there are distal effects and sometimes not - why some people use a light therapy device and get fantastic results, when someone else with the same training gets no results and decides these gagets are useless. Understanding the mechanisms is a nice idea, but I'm not sure we'll ever have all the bits of the n-dimensional jigsaw puzzle in place - and if we did, whether we'd understand it anyway !

                 I still advocate trying to make sense of it all is we can !! We just have to remember that the mind-body complex is still reasonably incomprehensible to us, in spite of all medical science has done.

Sorry - I get carried away with the mind-bogglingly incomprehensibleness of these things we call humin beens sometimes !

Peter Jenkins wrote:

I would prefer to see a coherent light probe of a specific wavelength compared to a non-coherent light probe at the same wavelength and output power.   Even go one step further and diffuse the laser beam to the same PD as the LED.

                 Another good point in the argument about multiple wavelengths being used together:   If 2 or more wavelengths are used together,   a) how do we know which is working,  and   b) how do we know that the particular combination used is not actually producing a lesser response than that produced by a single wavelength (all other parameters the same).

                 Life will only get simpler if we simplify the parameters with which we're working, understand the actions and effects of those parameters, and then reconstruct the complexity from a more knowledgable foundation.

                 Unfortunately we are not drug manufacturers, we want to heal our patients and send them away, not provide them with a consumable that they must consume for the rest of their lives, which of course they must buy from us for the 20 years that our patent runs...

                 We are all expected to keep lowering our prices because the technology is becoming more affordable, but the technology is only a small part of the equation:  There are many hidden costs, such as product development, compliance, and plain old marketing, that add significantly to the rolled-up costs of each laser sold (it's not exactly a high volume market now, is it?!).  On top of that we have research costs. We end up with a situation in which research is being conducted with equipment that is readily available, not what is optimal for the task.

                 Unfortunately for manufacturers, the results of any research they may have funded end up in the public domain (where they belong), thereby ensuring everyone benefits from their hard-earned contributions to research:  Hardly an incentive for research investment!  We can't even get protection via patents, etc., and so it's easy for other manufacturers to pick up on new technologies and package them differently, make them cheaper, and so on.     

                 It's a "tragedy of the commons" type of argument:  We can all collectively exploit the benefits of research, so there's no benefit in contributing individually to that research.  Of course privately-run research can be kept confidential until a product is on the market, and there are some benefits in being first to market, but the rewards are short-lived once the information is in the public domain.

                 It's an ongoing conflict between wanting to increase the available body of knowledge - and thereby increase the market's overall size and sophistication - and trying to make some return from our investments in these markets by maintaining whatever competitive advantage we may have. That's a commercial reality.  How do we, both as manufacturers and practitioners interested in developing the future of LLLT, overcome the research funding dilemma?  Sorry, I don't know.  Perhaps through this email forum we can find some answers.

                 Where and how is the limited research funding best spent?  Maybe the practitioners in the group can help us on this one:   what are your priorities?  Is it laser v LED, optimal wavelengths, or the old cost-benefit chestnut (some benefit is better than optimal benefit if the price is right, so investment should be made in making existing products cheaper)?

To summarise:

1.  More research must be conducted to determine the outcome of the Laser v LED debate;

2.  We are still, effectively, only at the stage of defining the questions that will hopefully be answered by further research;

3.  Manufacturers must use the correct terminology to describe the type of emitter(s) used in their products;

4.  Combinations of lasers and LEDs, and of different wavelengths, in cluster probes should not be used in research (and accompanied by appropriate explanations and disclaimers when sold for general use);

5.  LLLT research cannot be used to justify LED equipment, or to infer the benefits of LED therapy (this could apply equally to pulsed v continuous wave lasers);

6.  In vitro research doesn't necessarily translate directly to in vivo application (not really part of the debate so far, but a very valid point made by Jan in an earlier discussion);

So where do we go from here?   Any suggestions?    There must be more than four or five of us in the "Laser Therapy" discussion group, so let's have some new input:   we're all going to benefit from a broader perspective.

J. Streeter wrote:

List members,

Interesting discussion lately about LEDs. I was wondering if anyone knows what the optimal power density (Mw/cm2) was for the treatment of acute tendon injury using these LED devices?

Peter Jenkins replies:

Can't help with an "optimal" PD, but would suggest that the depth of tissue surrounding the tendon and the wavelength of the light-emitting device would need to be taken into account.

                 As for the healing effect, this is more likely to be optimised by the delivery of a specific wavelength at a particular energy density which is appropriate for the particular type and severity of injury,  once the required depth of penetration has been achieved.

                 This, of course, assumes that LED devices could actually be used for treating tendon injuries (in light of the current debate, we can't assume that LEDs will actually have any effect at all simply because lasers do).

Peter Jenkins:   I agree in principle with a lot of what you say here, but from the perspective of swaying the opinions of administrators such as Australia's TGA, and America's FDA, and of gaining credibility in the main-stream of medical practice, we need to be a little more rigorous in our approach to LLLT: otherwise we will remain on the fringe of acceptable therapeutic practice for a long time to come.

                 Compliance is already a minefield in Australia, where the TGA doesn't differentiate between low level lasers and "hot" surgical lasers, and yet it does differentiate between lasers used for acupuncture and cosmetic applications (whether they be hot or "cold" lasers), and those claimed to have "therapeutic" applications, such as in physiotherapy.

                 For example, the latest advice (but they won't put it in writing) from the TGA is that I can offer a laser unit for sale to an MD as an "acupuncture" laser, and not be required to comply with IEC601-2-22 standard (only the generic laser safety standard, EMC, etc.) ad can be self-declared as compliant. However, if I offer the same laser to the same MD as a "therapeutic" laser, it must not only comply with IEC601-2-22, but compliance must be also verified by a NATA-accredited test agency (and so up go the costs).     Figure that out!

                 Also, IEC601-2-22 relates only to Lasers:   LED devices only need to comply with the fundamental aspects of electrical safety, not laser safety, thereby significantly reducing the compliance costs (this should therefore be reflected in the price of such equipment...).

                 If we don't apply the same degree of academic rigour to the development of our body of LLLT knowledge as we would, say, to our understanding of natural medicines, then we will remain on the fringe of the regulatory frameworks and will consequently miss out on the significant investments in research that may be made available for LLLT if it were accepted as a main-stream modality.

                 Further, if we can't adequately define the respective benefits of Lasers and LEDs, we are left with the discrepancies that have already lead to such outcomes as the misrepresentation of LED devices as lasers and the consequent over-pricing of such products, which doesn't do the photobiomodulation market any good overall.

                 Re in vitro v in vivo, I agree (please see my previous response to Peter, summary point 6).

Karen Carroll:  I just think we have to keep a balance so that people who are treated with laser/led devices aren't reduced to experiments conditions. The rigor applied to testing depending on application sounds crazy - I am sure it had a rational basis in someone's head at some point.

                 Of course lasers should be sold as lasers and led devices should be marked and sold accordingly, and I still contend that "Laser Therapy" has become a generic term for using laser/led to stimulate healing.

Peter Jenkins wrote:

There's three distinct groups:   the researchers, the practitioners, and the manufacturers, who all have essentially different but inextricably linked motivators.  But the recipient of our combined efforts is the client.

                 I didn't mean to infer that clients should become lab rats.  This sort of research should be conducted in the lab first, and then on the lab rats, oops, I mean consenting clients.  And I totally agree that, from a practitioners perspective at least, what works for the client is the most important factor.  After all, they're why we are all ultimately in business.

                 As for that other group - the legislators - the TGA's rationale is apparantly that acupuncture and cosmetic therapy is not actually therapeutic, and therefore tools used for these practises cannot be described or advertised as therapeutic goods or devices.  If they can't be called therapeutic goods, then there's no need to regulate their use.

                 If they regulate acupuncture practise and equipment, they would essentially be accepting it as a valid therapeutic modality - and apparantly they're not prepared to do that yet.  And whereas they have not accepted lllt as a valid modality, a laser used in an "approved" therapeutic practice - such as physiotherapy - must be regulated.  I wonder what they would say to a laser targeted at a "low level laser therapist"?  If they require it to be regulated, then they must be accepting lllt as a valid therapeutic modality...  I think I might test them on that!

                 I concede that, within certain circles, "laser therapy" has become an accepted generic term:   I even use it myself.   However, it does create a potential for confusion for those who are not already "in the know", creating a sort of "cultural barrier" to those outside the fraternity.  OK for those within, but it doesn't help when dealing with regulatory bodies, newcomers to the field, etc., who then tend to lump all lasers together (except for AP!) as one.

Karen Carroll wrote: 

The rigor applied to testing depending on application sounds crazy - I am sure it had a rational basis in someone's head at some point.

                 If we don't apply the same degree of academic rigour to the development of our body of LLLT knowledge as we would, say, to our understanding of natural medicines, then we will remain on the fringe of the regulatory frameworks

                 As long as we are prepared to keep looking at what works from patients points of view rather than anything else.

                 Further, if we can't adequately define the respective benefits of Lasers and LEDs, we are left with the discrepancies that have already lead to such outcomes as the misrepresentation of LED devices as lasers and the consequent over-pricing of such products, which doesn't do the photobiomodulation market any good overall.

Lars Hode wrote:

Light Emitting Diode Therapy (LEDT) or Low Level Laser Therapy (LLLT), that is the question . . .

In my first mail, I pointed out the following:

There are still no investigations showing that LEDT is as good as LLLT although many comparisons have been made, also with different dose levels (in the present debate it has been said that it might just be a question of dose).

                 I also said that both Jan TunÉr and I are convinced that LEDT works. I have also personal experience from a unit named "Pretor" having 5 LED's, (940 nm wavelength and 25 mW total output) and a unit named Lasersun with a single LED 940 nm wavelength and 15 mW output. Said first device has been used both on humans and horses. So I know that LEDT works.

                 But I am also convinced that LED units are produced only because they are cheaper and easier to power than lasers and not because they have been evaluated and compared with lasers by their producers. It is hence not surprising that producers of LED instruments have been the most active ones in this discussion.

                 James, I am sorry that I could not be quite as generous to the LED therapy as you wish. LEDT has to prove its own potential, just as the lasers have. Also, I don't think we are so negative to LED in the book (Low Level Laser Therapy - Clinical praxis and scientific background) as you say. So, in order to make it possible for everyone to see exactly what we wrote in the latest book, I enclose four pages from chapter 11:

...oo00oo...

11.1. Are the biostimulative effects laser specific?

All forms of light affects the living organism. It has been shown that white light in certain doses influences seasonal depression conditions [240] see further page 258. It is essential to clearify whether or not the biological effects obtained with laser therapy will appear only if the light source is a laser - that is, if the effects are laser specific. This is not just of theoretical interest. If one could just as well use a light bulb with a polarization filter and/or a colour filter - or ordinary light emitting diodes (LED) with a certain colour or with infared light (such as in remote controls) - it would be considerably less expensive to manufacture therapeutic instruments. Many producers of therapeutic instruments claim that treatment with LED:s is as effective as laser treatment. Then they make references to laser research in their marketing, obvioulsly due to lack of support for LED effects.

 We will discuss this problem closely in the following chapter and the reader will, hopefully, feel more enlighted on the subject after having read this part of the book.

11.1.1. Is it possible to prove that LLLT doesn't work?

 New knowledge and treatment modalities within medicine have not always been well received. When Louis Pasteur claimed that there are small microscopic beings that makes meat decay, he was scorned by his contemporary colleagues. "But", "said he, have a look for yourself in my microscope!". His colleagues laughed and said they would certainly not do that!

 It is an interesting phenomenon that phycisists have entered the debate, trying to prove that LLLT just cannot work. As an example of this, we have chosen to discuss an article by P King [12] who, like P Greguss [233, 234, 235] before him, maintains that therapeutic lasers cannot work because it would be contrary to the laws of physics. King and Greguss claim that:

(A)  In terms of their biological effect, lasers may just as well be replaced by a "normal light" with the same optical characteristics, due  to the laser light's loss of coherence through scattering in tissue, and

(B)  Laser light can have no medical effect, due to its minimal penetration in tissue.

We consider this to be a mistake, on the basis of the following:

 Firstly: There have been quite a number of studies conducted on laboratory animals [13, 14, 15, 16, 17, 158, 204, 205, 253, 332, 426, 493, 511, 659, 750] – even blind studies – in which the effect of laser light was compared with the effect of light from other sources, such as LED’s. A significant effect was observed with lasers, which was not achieved with the other, less narrow-band light sources. Conclusion: Either all the investigators who conducted the research cheated, or the effects are specific to laser light.

 Secondly: The coherence of laser light is not lost in tissue due to the phenomenon of scattering. Light is neither coherent nor incoherent but is more or less coherent (see the term coherence as explained above).

 Thirdly: There is no "normal light" with the same optical properties as a laser; although if one did exist, it would of course produce the same biological effects as a laser.

 Fourthly: The penetration of light into tissue is not minimal. This will be discusse on page 254-257.

11.1.2. Comparisons between coherent and non coherent light

 In the literature there is a good support for the hypothesis that at least some of the biostimulative effects in vivo are laser specific. In fact, we have not yet found one single study indicating that non coherent light is as efficient as coherent light. This does not mean non coherent light is not a useful therapy, only that it is less efficient and probably only efficient on superficial structures.

Literature:

Bihari [13] treated three groups of patients with long-standing crural ulcers with HeNe, HeNe/GaAs and non-coherent unpolarized red light, respectively. Groups 1 and 2 demonstrated excellent healing, with group 2 slightly better than group 1, compared to group 3 with a low effective percentage.

Kubota [14] found that 830 nm GaAlAs laser increased flap survival area in a rat model. Laser treated flaps had better perfusion, a greater number of larger blood vessels and significantly enhanced flow rate. There was no difference between control and LED 840 nm groups.

Berki [15] used a HeNe laser to stimulate activation of cells in vitro. These effects (increased phagocytic activity, immunoglobulin secretion) were not seen when irradiating the cell cultures with normal monochromatic light of the same wavelength and doses.

Muldiyarov [16] used HeNe laser on zymosan arthritis in rats and found that the laser exerted and evident therapeutic effect. Analysis of the cases where the rats were treated with ordinary red light revealed no essential differences from the control group.

Haina [17] compared the effects of HeNe-laser and incoherent light of the same wavelength. Experimental wounds were punched out in the muscle fascia of 249 Wistar rats. In the HeNe groups, the granulation tissue increased 13% at 0.5 J/cm2.and 22% at 1.5 J/cm2. The increase in the incoherent group was less than 10%.

Rochkind [158] compared five different wavelengths, giving a single transcutaneous irradiation to injured perpiheral nerves. HeNe prevented the drop in functional activity following crush injury. 830 nm laser was ineffective, 660 nm incoherent light was even less effective and 880 and 950 incoherent light was completely ineffective.

Laakso [253] studied to relationship between LLLT and opoids. In a double blind study 56 selected patients with chronic pain conditions were treated with 820 nm LLLT 25 mW, 670 nm LLLT 10 mW or 660 nm LED 9.5 mW. ACTH and § -endorphin levels were significantly elevated in the LLLT groups but not in the LED group.

Pöntinen [332] compared the effect of laser light and light from a LED-source on head skin blood flow in 10 healthy men, using laser doppler technology. Doses were from 0.1 to 1.36 J/cm2. Skin blood flow was measured before, immediately after and 30 minutes after each treatment at 4 sites on the scalp. The conclusion was that 670 nm laser induced a temporary vasodilation and increased blood flow when the dose given was in the range of 0.12 - 0.36 J/cm2. The non-coherent visible monochromatic irradiation (LED: 635 nm) with doses between 0.68 and 1.36 J/cm2 decreased blood flow at least for 30 minutes after irradiation.

Lederer [426] found that “irradiation with coherent HeNe laser light effected leucocytes in migration inhibition assays. Incoherent light of the same wavelength and power density showed no influence.”

Rosner [493] evaluated the ability of HeNe laser to delay the posttraumatic optical nerve degeneration in rats. The optical nerve was crushed and irradiated through the eye. Interestingly enough, irradiation immediately before the injury was as effective as irradiation beginning soon after it. Non coherent infrared light was ineffective or had adverse effect. However, the non coherent light had a wavelength of 904 nm, which makes comparisons difficult.

Nicola [511] developed a technique of causing highly reproducible inflammatory lesions on the skin of rats. HeNe 1 J/cm2 produced an acceleration of the healing process. Incoherent light of the same wavelength and dose was less favourable.

Onac [659] compared the effect of HeNe laser and monochromatic light at 618 nm. The intact skin of guinea pigs was irradiated with different doses. They not only compared the two different light sources, they also compared them at different doses (from 0.63 J/cm2 and up to 38.1 J/cm2) and came to the following conclusion: Non coherent monocromatic red light irradiation leads to tegument trophicity at 4.96 J/cm2 (but less than HeNe-laser); lower doses have no effect (but HeNe laser had) whereas higher ones causes focal epidermic hypertrophy. Thus, the therapeutic window seems to be more narrow for monochromatic non coherent light.

Nicola [750] investigated the role of polarization and coherence of laser light on wound healing in rats. He had four groups of wounds:

#1 was treated with coherent and polarized HeNe laser light  (l=633 nm).

#2 was treated with non polarized, coherent HeNe laser light (l=633 nm).

#3 was tretated with polarized, low degree coherent light      (l=633 nm).

#4 was untreated and served as control.

 After the fourth treatment, leasons #1 had healed completely; lesions #2 had not healed completely but showed more advanced healing process than lesions #3. The leasons #4 showed a poor degree of cicatrixation when compared to lesions #1, #2 and #3.

 One investigation that unexpectedly strengthen our hypothesis that most treatments of tissue are laser specific, is published by, Zhou, [825]. Thee study concerns PDT (Photodynamic therapy) using three light sources: a) copper-vapour pumped-dye laser, b) HeNe laser, and c) non-coherent red light (filtered from a halogen lamp), when irradiating the liver in normal mice. (International Conference on Photodynamic Therapy and Laser Medicine). The mice (each group containing 18 - 20 mice) received hematoporphyrin derivative in a dose of 10 mg/kg intra- venous, 24 hours prior to light irradiation. The mice livers were directly irradiated with different red light at a dose of 5, 10, 25, 50, or 100 J/cm2, respectively. Forty-eight hours later the mice were killed, and the depth of liver necrosis was measured using a computer image-analysis system. No necrosis was found in the control liver irradiated with 500 J/cm2 alone. The depth of photodynamic necrosis showed a light dose-dependent response. The mean depth of necrosis of all groups were compared statistically. The Cu-dye laser showed the best effect while the non-coherent light showed the poorest. There were significant differences between non-coherent light and laser irradiated groups, but not between Cu-dye and HeNe laser groups. The results indicate that among the examined light sources, the Cu-dye laser is most suitable to photodynamic therapy (PDT) of tumors. However, the halogen lamp with a special filter device may still be occasionally used as a light source in PDT if needed.

In a wound healing study by Lowe [851] mouse skin was irradiated with 20 Gy X-ray irradiation. 72 hours later a wound was made on the dorsum and the area was treated with 890 monochromatic LED light three times weekly. There was no effect on the wound healing using 0.18 J/cm2 or 0.54 J/cm2 but an inhibiting effect at 1.45 J/cm2.

...oo00oo...

So far from our book.

I can agree with James that too litle research is done on the effects of LEDT and I also think that it would be valuable for you, James, and other maufacturers to find out which wavelength, dose, power density, pulse frequency etc is good for what condition when you are designing your LEDT-instruments.

                 Now, about penetration: It is not so that laser light of a certain wavelength and power density penetrates better than non coherent monochromatic light (e.g. LED light) of the same wavelength and power density. The two primary factors influencing light penetration in tissue are wavelength and pressue. If a laser probe is pressed against the skin, the blood in the compressed tissue flows out sideways leaving the tissue right under the probe aperture bloodless. And as the blood accounts for the major part of light absorbtion, the penetration increases a great deal. Coherency does not influence the transmission. But: coherency influences the microscopic light distribution in tissue due to interference in the scattered light field.

                 But it is true that it is easier to achieve higher power density with lasers than LED's, but this is not the general reason for the better results. The coherency is of importance.

                 I agree with Peter Jenkins that probes with only one type of light source is to prefer in all scientific work. Mixing wavelengths inevitably decreases the length of coherency of the light emitted. And generally, I agree with many of Peter Jenkins opinions. (I will comment them later in more detail and also several other statements in this debate.)

                 I think that every device claiming to heal, has to prove its own effectiveness in controlled studies. That is the best tool we have after all. Just to say that "it is as good as ..." is not good enough.

                 Finally, as I think it has been an interesting discussion. I would like to know if any one of the participants dislike the idea that we put in the discussion in LaserWorld, so that many more interested in laser therapy can read it. Please let me know as soon as possible.

Peter Jenkins wrote:

I support Lars' idea to put the current discussion in Laser World. The benefits will be at least twofold: firstly, the debate will be more accessible and may help to increase the general lllt populace's awareness of the LED/LASER issue (thereby potentially saving many practitioners lots of money on inaccurately specified equipment, and perhaps convincing the research fraternity that LED-specific research is valid and necessary), and secondly, to generate awareness of the discussion group and hopefully entice more to enter the fray.

                 I also appreciate Lars' comments regarding the need for manufacturers to determine the correct wavelength, dose, power density, pulse frequency, etc. Karu and others have shown that, at least in vitro, pulse frequency, duty cycle, etc. do affect the outcome of irradiation, although the degree to which this happens is yet to be determined.

                 As with the LED v Laser debate, there is no doubt that both CW and pulsed lasers are effective for LLLT. But can we then simply assume that dosage and other parameters are directly transferrable between the two? Similarly, can we assume that the particular pulse frequency, duty cycle, etc. that we have chosen for our equipment is optimal?     

                 I believe the answer to both these questions is "no". Firstly, we can no more assume that CW and Pulsed laser dosage parameters are equivalent than we can assume the same for Laser and LED. Secondly, the pulsing parameters of laser diodes used in LLLT equipment are primarily determined by the diode's manufacturer, not by the science of LLLT. The science of LLLT is not yet that advanced.

Valery Zakharov wrote:

Hi, All!     First of all I must mention that I read with interest the message of Lars Hode. Sorry Lars, I do not have a possibility to read your new book (but have a great wish). It is very pity for me. But the last Lars message give me the understanding of his main thoughts. Forestall the results pointed below I may say that he is right in many things, but not all of them. Moreover I make bold to say that some causes have inaccuracies.

                 I see a discussion LED vs LASER, that mainly based on empirical data. But we have made a special investigation in order to see how blood changed as a responce on such influence. It is a biophysical investigation, so it is free of some "psychological" factor that usually take place in practice. I also want to mention, that it is only small part of a whole scientific-research project.

                 It also must be mention that the most of the investigations and comperations between laser and LED irradiation were based on the results of treatment. I agree, that the practice is the best referee, but it is very hard to create the same conditions due to difference of technical divices. The second factor is that such type of investigation may give truthful results only in the case of a big statistics. The third point is that nobody can exclude the psychological factor. And I may write more factors that make difficult the understanding of the problem.

                 So, we must very carefully appreciate the mechanism of laser (or LED) treatment in order to understand the difference and analogy in the effects that take place in every of these cases. Thus I try to write shortly our conception on this theme.

                 The main laser features are the following: monochromatism (do not have any effect in restructure process, but may be this factor is important in penetration or channeling of electromagnetic energy to the human liquid), coherence (the same), polarization (one of important restructure factors), small divergence (one of the main factors of channeling the energy without transformation of its features, such as direction of diffusion). So we see that the main advantage of Laser therapy under LED therapy lay in the field of good channeling of its energy to blood through skin and surface tissue.

                 We arrange and fullfil a cicle of experiments (model and clinical) in order to receive comperetive data. Shortly we compare:

1.He-Ne (polarized) laser

2.He-Ne (artificial depolarized) laser

3.UV laser (337 nm)

4.semiconductor lasers (670, 830, 900 nm)

5.nonlaser termal radiator (wide spectrum, polarized)

6.nonlaser termal radiator (wide spectrum, depolarized)

7.IR LED (polarized)

8.IR LED (depolarized)

The best results give devices 1,3,4. Device 2 in comparison to 1 give from 30% to 80% delay for different circumstances. There are no response on biophysical model and the same (no positive clinical results) in treatment for devices 6 and 8. The responce for radiation of device 5 was very weak on biological model and we receive no positive clinic on it. Device 7 give positive clinic results, but allways low in comparison with device 4.

                 We are open for any discusions and colloboration in any type of work in laser medicine: biophysical investigations, medical laser design, development of laser medical methods in a wide range, and laser medicine education. The last is based on the course of lectures and our materials.

Lars Hode wrote:

Hello Valery. Thanks for mail. You have performed some very interesting experiments. I would appreceate to get more material. Your conclusions based on comparison of biologic effects of different types of light just further confirms the difference between LLLT and LEDT:

1.    Best results was received with HeNe (polarized) laser, UV laser (337 nm) and

       semiconductor lasers (670, 830, 900 nm)

2.    Depolarized HeNe-laser gave 30-80% delay (you need to explain this to me).

3.    No positive clinical results in treatment with non-laser termal radiator (wide spectrum,

       depolarized) or with IR LED (depolarized).

4.    The responce for radiation from nonlaser termal radiator (wide spectrum, polarized)

       gave no positive clinical effect.

5.    IR LED (polarized) give positive clinical results, but allways low in comparison with

       semiconductor lasers (670, 830, 900 nm).

You mention the "psychological" factor, usually referred to as placebo. Yes it is important to be aware of this. The references I gave to studies comparing lasers with non coherent sources are practically all performed on animals and then the placebo effect is not so clear.

       Let us look a bit further into the primary mechanisms. Coherence itself is not the factor of direct biologic influence. But indirectly, it is of importance. In order to get effective interference, two light properties are necessary: polarization and coherency. In the scattered light field in tissue, statistically, local areas of polarization occur, and in the case that the light also is enough coherent, so called laser specles are formed through interference. The light intensity in these laser speckles can be tenfold stronger than the average light intensity - or even more.

       An interesting thing is that in a highly scattering medium - like tissue - it does not matter whether the laser light is polarized or not when it enters. In the scattering process, the degree of polarization goes down quickly. However, in a non scattering medium, like in vitro experiments, polarized light stays polarized all the way through the liquid. Hence, in open wound situations, polarized light can be advantageous, even polarized wideband light. Here it can be seen as "light channeling".

Again, two citations from our book:

        If we accept that laser light causes areas of polarized light in tissue (as earlier described), we might also ask the question: what is there in the body/tissue/cells that reacts to the light's polarization? Is there a polarization-sensitive element?

        Yes, there is. It is known that matrix fixed chromophore molecules (e.g. the body's porphyrins) possess absorption dipoles and both absorb and emit (e.g. through fluorescence) linearly polarized light [20] of a determined polarity. Porphyrins are just one of the elements in the mitochondria's respirator chain, and are the molecules chiefly responsible for the absorption of light. The polarization in the speckles created by laser light is significant here, and this could explain why the studies mentioned above showed different results with lasers and incoherent light sources.

Further, with higher irradiation levels (power density) the probability for multiphoton effects increases.

Even though ordinary daylight has good effects on us, it is very clear that there is a great difference in biologic effect.

11.3.5. Other interesting possibilities

An interesting hypothesis about the effect of LLLT has been put forward by Reznikov and Pavlova, based on three separate studies [728] [729] [730]. Reznikov [857] gives the following description:

        “Laser light could be considered as a trigger of an adaptive reaction because during evolution, this kind of "irritator" (stresser) is unusual, uncommon. There is not any physical agent besides laser light which we never experienced evolutionary - radiation, gravity, temperature, light, pressure, CO2 or O2 saturation, etc. Because of multiple exposure to changes of those conditions (effectors) during the evolution, listed effec-tors may induce stress only if they are approaching to damage (hazardous) range. The real therapeutic effect related to stress/adaptation, however, may be expected only if the effector does not add its own hazardous effect. Among all known cases it is possible only if laser light is applied at the low dose. Why?

        Unlike other physical factors, the light with narrow spectral band is absolutely unusual for our nature. There is no situation where bio-organisms on Earth could be exposed to this kind of light and develop unresponsiveness to that during evolution. Because of that, we believe that the most important for laser effects is not the wavelength but the mono-chromatic nature, especially with narrow spectral band.

        If we will excuse ourselves from the discussion on differences in light absorption and energy of photons (the important aspect of optimi-zation in LLLT) and will focus on the induction of adaptive reaction: the more "odd" light we are expose to, the more response we can expect. If the lights band-width increases, the effector loses power to induce adaptive reaction (even if this light still is considered monochromatic, at some degree, it may be not so unique evolutionary as the light with less band-width).

        In other words, extreme monochromatic light (such as laser light) exposure was not experienced evolutionary. As such, it is a stimulus, that is unique to the experience of the organism. The more unique the light, the more the organism is required to resort to adaptive mechanisms, to resolve the stimulus. For this reason, laser light is considered a unique adaptogen, generating adaptive reactions. The less band-width of the light, the more unique the light is to the experience of organism resulting in grater efficiency of LLLT.”

Peter Jenkins wrote: 

I support Lars' idea to put the current discussion in LaserWorld.  The benefits will be at least twofold: firstly, the debate will be more accessible and may help to increase the general LLLT populace's awareness of the LED/LASER issue (thereby potentially saving many practitioners lots of money on inaccurately specified equipment, and perhaps convincing the research fraternity that LED-specific research is valid and necessary), and secondly, to generate awareness of the discussion group and hopefully entice more to enter the fray.

       I also appreciate Lars' comments regarding the need for manufacturers to determine the correct wavelength, dose, power density, pulse frequency, etc. Karu and others have shown that, at least in vitro, pulse frequency, duty cycle, etc. do affect the outcome of irradiation, although the degree to which this happens is yet to be determined.

       As with the LED v Laser debate, there is no doubt that both CW and pulsed lasers are effective for LLLT.   But can we then simply assume that dosage and other parameters are directly transferrable between the two?  Similarly, can we assume that the particular pulse frequency, duty cycle, etc. that we have chosen for our equipment is optimal?

       I believe the answer to both these questions is 'no'. Firstly, we can no more assume that CW and Pulsed laser dosage parameters are equivalent than we can assume the same for Laser and LED.  Secondly, the pulsing parameters of laser diodes used in LLLT equipment are primarily determined by the diode's manufacturer, not by the science of LLLT.  The science of LLLT is not yet that advanced.

F. H. Lew wrote:

In my practice, I find that superficial injuries are adequately  and efficaciously managed by a light-emitting diode [LED] red light radiating device. Unlike the low level laser radiation which is coherent, collimated, and harmful to the retina, the LED red light radiating device is non-coherent [light rays tend to be divergent] ,does not burn holes in the retina and is cost-effective. It  can outdo the low reactive laser in many ways like healing injuries under zero gravity. NASA can testify to this property which is not demonstrated by low level laser therapy in outer space healing. I choose the wave-length 660 nm,which is resonant with all cells in the body. The continuous mode of radiation is employed for sedation and the control of pain,while pulsing at 266 hz/sec to activate biostimulation of the injured tissue for in- duction of intra-cellular regeneration. With simple nutritive support, the healing will be uneventful with imperceptible cicatrization. Colloidal Silver at 10 ppm is used both locally and orally for its regenerative and antimicrobial properties.

       The low level laser therapy poses the danger of harming the eyes because of  the coherence of rays of light. The coherence is fragmented into "speckles" when the laser beam penetrates the skin, which can cause burns to the cellular matrix. This does not happen with light-emitting diode red light therapy. The FDA's stand is obvious with Low Level Laser Therapy ! A LEDT device is not a laser.

       LLLT is just as good for soft tissue injuries but with LEDT, you get more for less. It is within everyone's reach to own a LEDT device but I cannot vouchsafe for the low level laser.If I am of any help at all, please do not hesitate to post. The LEDT devices I am using are purchased from America.

Peter Jenkins wrote:

Dear Lew,   Unfortunately it is falsehoods like this that has caused many of the problems we experience in trying to have LLLT / LEDT accepted as a serious, valid, and effective mode of therapy by practitioners, public, and regulators alike.

       It would appear that whomever sold you their LED product has created a good, yet overall completely false, sales pitch.    They've taken elements of scientific fact, stretched them, bent them, and drawn from them invalid assumptions and assertions, and then woven them all back into into a believable fairy story: what Richard Dawkins (Unweaving the Rainbow: 1998) would call 'bad scientific poetry'!

       Both LEDs and LASERs have the potential for causing optical damage, and both are covered by the same international safety standards (IEC 825-1 and IEC 601-2-22).   LASER light is coherent and LED light is not, however, both can be collimated using lenses.   Yes, LASER can be collimated more effectively than LEDs, however, it does not necessarily follow that LEDs are therefore less hazardous than LASERs.

       In fact, NASA acknowledges the effectiveness of LASER in the treatment of wounds, both on Earth and in space.   From my reading of NASA's research it appears that the only reasons they've chosen to go with LEDT are the reduction in cost and the increased ruggedness of LEDs compared with LASERs.

       660 nm is an effective wavelength, but as for being "resonant with all cells of the body", I have as yet seen no research to support this. 660 nm also happens to be one of the most commonly available, and therefore least expensive, LED wavelengths...  

       I think a lot of what you write can be summed up by looking at these last few paragraphs:  if you're trying to wend your way around the FDA's tight regulatory definitions so that you might exploit loopholes to sell a product, it makes good sense to mix good science with bad in order to create your sales pitch:  it makes the fairy story that little bit easier to believe!

       Another absolute doosie I've come across is that "LED light penetrates deeply into the body because acupuncture meridians act as optical fibres". This does acupuncture a great disservice!

       As a businessman I understand the pressure one feels to 'bend the truth' in order to create an image or improve sales figures, however, reputable businesses don't need to compromise sound ethics by knowingly using spurious claims to sell products. This is especially the case - as in LEDT - where there is perfectly valid, 'good science' available upon which a product can be supported.

       It is unwise, inaccurate, and unnecessary to denigrate LLLT in order to promote LEDT, as this just damages the image and reputation of two therapeutic modalities which offer so much to so many! It is also much wiser to do some research of your own before believing a sales pitch.

       You are quite correct in stating that LEDT is effective in treating superficial injuries.   Whether it is more or less effective than LLLT is a matter for further scientific debate.

       The fact is that LEDT is an effective modality, as is LLLT, and both have their place in therapeutic practice.

Lew, I hope I've not offended you in any way:  that is not my intention.  I simply wish to point out that the dissemination of 'bad scientific poetry', or spurious claims, does nothing to help the growth and development of LEDT and/or LLLT. I wish you good luck with your LEDT practice.

PS:   These are my personal views and opinions, and I stand open to any criticism.

Steve Deck wrote:

Ditto what Peter said. A lot of LED people think that their deal is the only way to go since they can’t get a real laser.  Lasers can be purchased in the US, the manufcturer just can’t say that they work, because the FDA hasn’t said so yet. However, we all know differently. Oh yeah, you can buy one legally to use on your horse or dog or any other vet. use.

Lew wrote:

Peter:  Thanks for the three dimensional dissection of the " bad scientific poetry ". It was a very impartial and reasonable stand on behalf of the gullible end users.Many claims are not genuinely proven and even then, the experimental results obtained are not from the original researchers. However, we can only make do with basic principles and common sense. In Malaysia, the laser diode pointers are banned because of the inadvertent hazard to the eyes. I have specifically requested my American supplier to label the parcel with the words: For Medical Use Only to expedite customs clearance.

       From my clinical review, the LEDT device truely works except for the exorbitant lay write up from some quarters. There are many areas in Low Level Therapy which are unchartered pending experimental research. Let us keep an open mind. Let us not mix up commercialism with scientific truths and safety. It is truely a very lively and refreshing change from the humdrum in your analytical comments. I, for one welcome such impartial exercises which perhaps have helped in correcting some of our preconcepts of LLLT and LEDT. It is through the findings of more research that we have more to debate or to talk about.  By the way, Peter, you stated:

       " LED light penetrates deeply into the body because acupuncture meridians act as optical        fibres ". This  does acupuncture a disservice!

Why do you say that ?

The LEDT device sent to me from America is made in Korea.

Peter Jenkins wrote:

Dear Lew,  I'm glad you've taken my comments in the way they were intended - as an 'impartial exercise' and not a personal affront.   I agree with your comments in response.

       For info, laser pointers are also banned in Australia - ostensibly because of the potential for eye injury.   However, when one looks at the beam characteristics of a laser pointer, and then refers to the international laser safety standards, one can easily see that the beam from a laser pointer would cause injury only if deliberately aimed at the retina (ie. with the eyelids forced open against the blink response) for a prolonged period and from very close range.

       Possibly, then, the main reason for the restriction of laser pointer sales in Australia is the potential for people driving cars, riding horses or bikes, and/or flying planes, etc., to be distracted momentarily by the brief but dazzling flash caused when a mischievous person deliberately targets them.

       It was quite common for pointers to be used to distract greyhounds and horses when they were about to start racing, thus causing them to miss the start and lose the race.   In fact, lasers have also been tested by the US Dept of Defence in a similar manner, but this time they were used to dazzle and confuse helicopter and jet pilots.  (In my experience - I spent 12 years in the airforce -  the best way to dazzle a jet pilot is with his own reflection!).

       Regarding the following comment:  "LED light penetrates deeply into the body because acupuncture meridians act as optical fibres".  This does acupuncture a great disservice!" This was inserted as another example of using common terms and facts to construct an false assertion:

"LED light (and laser) penetrates deeply into the body..."  TRUE.

"acupuncture meridians":   A well-known and commonly used term, which sounds sufficiently hi-tech to catch a lay-reader's attention.

"fibre optics":   Also well known.   Most people have at least a basic understanding of the fact that light passes through optical fibres and can travel great distances through this medium.

Each part of this statement is, in and of itself, ostensibly 'true'.  It is only when you put them together, and imply causality with 'because' and 'acts as', that the falsehood appears.   To the lay reader, however, this may not be obvious and, I'm sure you'll agree, therein lies the problem.

       Yes, LED light (particularly near-infrared wavelengths from, approximately, 780nm to 940nm) will penetrate deeply into the body, but no, this has nothing to do with acupuncture meridians acting as optical fibres (of course, if there is incontovertible evidence to the contrary I would be happy to review my position).

       The depth of penetration depends primarily upon the wavelength and power density of the beam incident to the tissue, and the absorption/reflection characteristics of the irradiated tissue.    Some research has shown that laser light may penetrate more deeply, than LED light of the same wavelength and power density, due to the presence of the laser speckles, which have a higher relative power density than the beam overall.  However, I believe that although the evidence used to support this postulation is convincing, it is yet to be proven conclusively.

       Whether there are in fact channels of energy flowing through the body (ie. meridians) is yet to be widely accepted by the strictly scientific medical community, but recent double blind clinical trials conducted using a placebo needle have shown statistically significant results in favour of acupuncture's effectiveness - whatever its mechanisms.  Much more research needs to be done, and even more effective blinding methods developed, before acupuncture will be generally accepted as a valid and effective modality by mainstream medicos.

       I believe that spurious claims like 'acupuncture meridians act as optical fibres' will do nothing to improve the level of acceptance of acupuncture by 'mainstream' medical institutions and regulatory bodies, such as Australia's AMA and TGA. Therefore, such claims are doing acupuncture (and other modalities they may be applied to) a great disservice.

Thanks again for your response.

 

Jan TunÉr wrote:

Whenever the issue of LEDT / LLLT appears on this list, the fire is on! There is not much to add to Peter« s lines, I think it was well put.To me, the reson for the excitement is not whether or not LED:s work, because I beleive they do. Too many persons that I know as serious individuals have stated so. The problem is the lack of studies confirming this experience. And whenever LED and lasers have been compared in a study (13 studies found), LLLT has come out on top. It may very well be that the LED parameters have been wrong, but the problem remains, LED:s have to prove themselves scientifically. And no references to LLLT studies should be made to "prove" that LED:s work.

       I think there is no need to create a front line between users of LLLT and LEDT, as a group we are to small to afford any internal quarrel. But it is important that we stamp out the desinformation propagated by various manufacturers.

       Some remarks about laser pointers: the ignorance among governmental "experts" is unbeleivable. Pointers are in the red and usually below 2 mW, although I myself have a 4 mW pointer. Since they are in the red, the blink reflex will protect the exposed eye. And to hit the eye from a distance is not easy, especially not when a person is in motion. Certainly the use of inexpensive pointers is becoming a nuisance with the young generation, but there is no risk of an eye injury unless you force the pointer into the eye...

Peter Jenkins wrote:

Thanks, Jan,  I could not agree more with your comments. It is quite intriguing that LEDT v LLLT is such an emotive issue. Clearly, a rational, well-balanced approach is what's needed, along with some good scientific data to back up the anecdotal evidence offered by many (including myself) in support of LEDT.

       At this stage, I would personally consider LLLT to be more effective, but I'm unsure of whether this is due to the laser's unique beam characteristics, or simply because laser therapy protocols have been more widely and intensively researched. Perhaps if protocols were developed specifically for LEDT, we may find the gap closing somewhat.

       I would hazard a guess that there may be many conditions/circumstances for which LLLT will always remain the superior modality, but that LEDT may be found to be more effective in others.  'Superiority' in this instance can also be subjective and circumstancial.  For some, LEDT may be considered the superior modality because the equipment is relatively more affordable on a limited budget - and therefore it may be accessible where LLLT may not - or because the ruggedness of LEDs is required for use in a particular environment.

       To reiterate the point I made in earlier emails on the subject by restating Jan's comment: "...it is important that we stamp out the disinformation..."!  This holds not only for within our discussion group, but also in the real world where ever possible.

       If anyone is using LEDT, please let us all know what sort of conditions you're treating and how successful it is.  If you utilise both LEDT and LLLT in your practice, what factors determine which modality you use for a particular case, and do you find LLLT or LEDT to be better / worse / effective / non-effective in various circumstances?  If you have used LEDT and found it completely useless, please, let us know.  But please let's stick to the empirical results and rational observations, not the hype and mumbo-jumbo! If you are conducting research, we would definitely like to hear from you.

       For now, however, and for want of sound scientific research, the LLLT v LEDT debate remains subjective.

Anu Mäkele

Hello all,  I guess I'm putting my head in the hornets nest for getting involved in this argument, but here goes anyway.

       The argument about LEDT and LLLT seem a little like arguing which is better, a car or a bicycle. Both get you were you are heading, the other is just more efficient, faster and easier (and costlier) to use. I myself have been using He-Ne lasers for about 18 years now, but we do sometimes recommend to some customers with persistent skin problems or fairly superficial inflammations a small 7.8 mW LED for daily home use. Since the LED works at the wanted wavelenght it still has the wanted effect with less penetration because the light is not coherent . The laser's effectiveness is based on BOTH the wavelenght and coherence. This is the why also different types of lasers are more effective on some problems than others. Different wavelenghts affect cellular function in different ways. This does not mean that one can say that any laser is better than some other, they are just used for different things.

       From the results we have seen, many of our patients have had good results using the LED, better than if they were having the laser treatment alone. This is mainly due to the fact that treatments can be repeated daily - so LEDs are handy helping tools to use when other treatments are difficult or impossible. They are also very good for burns and for small wound, so I keep one handy in the house for emergency use along with my laser.

Melyni wrote:

HI Guys,   Actually I use quite a bit of LEDT. I use the 104 diode probe on my THOR which puts out a lot of light. Total output is 2W. 

       I use it very succesfully on skin conditions, and most odemas which are not too deep. As I work with horses, who have a deeply pigmented skin and a hair coat, the use of some of the lower powered LEDs are VERY questionable, but the big 104 probe does a nice job of packing the light thru all the impedments. It will trigger the IR detector thru my hand so know it has some power of penetration.

       It also does a nice job of relaxing superficial muscles of the back prior to chiropractic manipulation and makes it easier to palpate deep trigger points in the hores. I use the Laser probe to treat the actual trigger points, but sometime I can't eve palpate them for the tight sore muscles in the upper layer of the back. The LED probe relaxes those and then I can feel better.

On me, I find that if I get kicked, or knocked, the LEd probe will stop the bruising developing on the affected area, provided I get onto it in time. LED's (IMHO) are great for open wounds, big amorphous swellings that are close to the surface, and for relaxing tight sore muscles.  They are also great for reducing pain in very recent trauma, but to get deep you need a laser probe too.

Lew wrote:

Jan, you wrote:   “Certainly the use of inexpensive pointers is becoming a nuisance with the young generation,but there is no risk of an eye injury unless you force the pointer into the eye.”

       The role-playing antics of children are not to be underestimated. An anxious mother bringing a child with blepharospasm. [ a twitching  contraction of the eye muscle as a result of some nervous irritation to the eye] can be very trying to the medical attendant  unless a high index of suspicion is maintained of the games children love to play. Playing doctor examining the eye with a carelessly kept pointer  or a toy pointer among siblings or other children, has to be seen to believe it. In retrospect, I could have missed a few similar cases because I did not ask the parents: Do your children or their friends play with toy pointers ?

Ann Angel wrote:

Just for the record:  Laser pointers are not banned in Australia, just limited to 1mW.  This was to stop the 5mw cheap Taiwan units that children were getting hold of for a few dollars.

       There are many laser pointers in Australia that meet the new guidelines.  These guidelines are not Australia wide yet, but it is likely to go that way shortly.

       Laser pointer type devices that are used for medical appliactions and are registered with the TGA (Therapeutic Goods Authority) are not restricted to 1mW.

------------------------------------------ I will draw a line here ------------------------------------

Thank you all for this interesting debate! If you have any agreements or disagreements, you can either use the ListBot, or send an Email directly to me on

lars@hode.com Lars Hode



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