You said
"One last thing. Potentially the difference between the home based
units and the more powerful medical quality units is in how frequently
treatments must be administered. It appears based on posts that I've
read from users of home based units, that they seem to work best with
more frequent use, whereas the medical quality units seem to allow
more infrequent treatments. Just a thought..."
Most of the treatments that I have seen listed in the various studies, including the NASA study, list their treatments in Joules per square centimetre. As you would probably already know, A joule is a measure of a Watt Second, Therefore to rewrite what you have said above in other terms, you can receive the same amount of Joules by receiving a higher power level for a shorter amount of time, as a lower power level for a higher amount of time.
What I was trying to say in my previous e-mail is that the characteristic operation of an LED dictates the amount of light output you can receive from it regardless of the drive current. As you provide more current to an LED, the unit heats up and the efficiency of the LED drops off as more of the power is lost as heat and not light. LED's are normally supplied with a data sheet that states their optimum drive current, beyond which, too much heat is generated and the light output is lost. Scroll down and Look at 'Figure 2 – Emitter Characteristics – a) LED' for a graphical representation of my poor wording.
http://www.fiber-optics.info/articles/LEDs.htm
So there is a limit to the light output of an LED, and as I said before, unless there is some special High light output LED that is not commercially available, then any LED light output levels would be able to be replicated by a standard person building a unit at home as you can purchase power sources many many times the thermal limiting drive current of an LED.
I understand what you mean about his need to be cautious and speculative. I was expecting systematic scientific evidence after viewing his name associated with being a specialist in laser and LED therapy when maybe only anecdotal evidence currently exists.
Thank you for the references, I think we have discussed these before. The second reference refers to a laser so It's hard to compare power levels of a Coherent Linearly polarised device to an Incoherent Randomly polarised device (LED).
Looking back over all the links we have seen to the clinical studies in Pubmed, I think there is a little confusion somewhere. LLLT can refer to Low Level Laser Therapy and Low Level Light Therapy, where Low Level Light Therapy can encompass LED Therapy as it is a form of light. However, all the clinical studies Reference LLLT as Low Level Laser Therapy.
All of the clinical links in the rosacea resources reference a low level laser and not an LED. Maybe it could be better to split it up into Low Level Laser Therapy and LED Therapy?
With this aside, It seems that the only clinical study on LED's that we can possibly use as a benchmark is the NASA study.
http://www.lighttherapyproducts.com/LEDNasastudy.html
You mentioned you don't know how they compare to home units. I don't know if they can be compared at all. But if you had to make a comparison, from the example given previously
"with a power density of 31.3 mW/cm(2) in 42 sec
significantly reduced TNFalpha level to 50.2 (95% CI, 49.4-51.0), p <
0.01 units/mL versus control.":
http://www.ncbi. nlm.nih.gov/ entrez/query. fcgi?db=pubmed& cmd=Retrieve& dopt=Abstract& list_uids= 16503786& query_hl= 25&itool= pubmed_DocSum"
31mW in a period of 42 seconds is the equivalent of 1.302 Joules.
This is the best I'd be able to do…
The following is a link to the data sheet of the Near Infra Red LED's that I ordered.
http://www.avagotech.com/assets/downloadDocument.do?id=1846
If you scroll down to the 'Radiant Optical Power' in the parameter field in the table, you can see it emits 19mW with a Forward Drive Current of 50mA and 38mW with a forward Drive current of 100mA.
Using a 100mW drive current you would get 38mW Radiant Optical power. The Power levels, IF comparable, between Coherent Linearly polarised device to an Incoherent Randomly polarised device are relatively similar. BUT we are talking about different animals here.
With a typical voltage drop of 1.5V across each LED, a standard 240V/12V AC/DC 4 Amp power supply (Around 50 bucks from your local electronic store) could supply around 480 of these LEDs which could cover a significant area.
Once again though, that is comparing the power levels of a laser to an LED.
Clearly more studies need to be done on LED therapy. It is all too vague.
Matt.
Hi Matt,
You're absolutely welcome. And you're right in that we do owe Dr.
Goldberg a big thanks for taking the time to answer some of our
questions to the best of his ability. I personally was very happy he
took the time to answer our questions as you'd be surprised how few
researchers and doctors are willing to do so. And of course I always
want to know more, but still, his answers reconfirmed some of my own
opinions on LLLT.
As for some of your questions though, I've found in my admittedly
limited interactions with medical researchers and doctors that they
are a very cautious group. They rarely seem to speculate, and they
nearly always use terms like "evidence seems to suggest" when
answering questions about mechanisms of action, etc.
I certainly cannot put words in any of these researcher's and doctor's
mouths, but I personally use terms like this when answering questions
about studies I've read, etc as I'd absolutely hate to give a
definitive answer to someone and then find another study later on that
suggests yet some other answer. This seems to particularly possible
when the science or technology is in its early stages of use and research.
To answer some of your questions though, based on my own readings of
the studies in pubmed related to LLLT devices, studies do seem to
suggest that, particularly red/near infrared LLLT devices are
antiinflammatory and antioxidant in nature, affecting TNF-a levels and
thus other cytokines and enzymes that are involved in inflammation as
well as superoxide dismutase levels which is key in clearing the
reactive oxygen species (ROS) that are responsible for cleaning up the
oxidants products of inflammation. See the RSRP for more info on this:
http://rosacea- research. org/wiki/ index.php/ Red_LED_Lamps_ %26_Other_ Forms_of_ Low-Level_ Light_Therapy
As for the quality of light output, the following study also on the
RSRP page above mentions that reduction of TNF-a is LLLT dose
dependent, and a 650-nm Ga-Al-As laser "LLLT dose of 0.11 Joules
administered with a power density of 31.3 mW/cm(2) in 42 sec
significantly reduced TNFalpha level to 50.2 (95% CI, 49.4-51.0), p <
0.01 units/mL versus control.":
http://www.ncbi. nlm.nih.gov/ entrez/query. fcgi?db=pubmed& cmd=Retrieve& dopt=Abstract& list_uids= 16503786& query_hl= 25&itool= pubmed_DocSum
How this compares to the home units, I unfortunately don't know.
Hopefully additional studies will shed more light on these questions
in the future...
I hope this helps some. Hang in there...
Dan
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