LED vs. Laser: is the jury still out?

August 28, 2005

Hi Alon, & All,

Cameron wrote:

> I just want to overcome the last hurdles of disbelief that LED and

> Laser are not dramatically different in effect. Otherwise sign me up.

Alon replied:

> a laser light disperses as soon as it hits the skin. Buldry has some

> ref regarding laser compared to any regular light. Bales used to work

> for NASA and his information, i believe, has not been published. He is

> a close friend of one of the MDs i work with so i get to ask him many

> questions. But i can have you do an easy experiment. Infrared laser and

> LEDs can light up a special card. For all the people that claim how

> deep these penetrate just take the IR card and put it near the palm of

> your hand and then put the laser on the dorsal side. You will be

> surprised to see that so little energy passes that the card will not or

> just barely light up. You loose 1000th of the energy for every mm of

> penetration because the beam disperses immediately.

Darren Starwynn wrote: " There is quite a bit of controversy among light

therapy proponents about the therapeutic value of lasers, which produce

coherent light, versus LED and incandescent sources, which produce

incoherent light. Laser enthusiasts, backed by a large body of research,

claim that only the intense, highly coherent beam of a laser can

penetrate deeply into the body's tissues and meridian system for

significant results. Yet some of the most respected names in light

therapy research have used gentler, much more diffuse light sources for

effective treatment of a staggering range of health disorders. Who is

right? " for the rest, see:

http://www.acupuncturetoday.com/archives2004/jun/06starwynn.html

Darren, WHICH do YOU use: laser or incoherent light?

http://www.providencemed.com/Laser_vs_LED_Therapy.htm says: " A

number of studies have been completed that compared the

effectiveness of laser light to LED light and the majority have found laser

light to be far more effective, particularly in treating tissue of any

significant depth. While LED light therapy does have some beneficial

effect, it is limited to superficial tissue treatment only. The authors of the

leading and most widely used laser therapy textbooks are unanimous in

their opinion that there are significant differences between laser light

and LED light and that their respective biostimulative effects are far from

being equal. The preponderance of opinion is that laser light (LLLT) can

achieve much greater and deeper stimulative and therapeutically

beneficial effect. "

Best regards,

Tel: (H): +353-(0) or (M): +353-(0)

Ireland.

Tel: (W): +353-(0) or (M): +353-(0)

" Man who says it can't be done should not interrupt man doing it " -

Chinese Proverb

August 28, 2005

leading and most widely used laser therapy textbooks are unanimous in

their opinion that there are significant differences between laser light

and LED light and that their respective biostimulative effects are far from

being equal. The preponderance of opinion is that laser light (LLLT) can

achieve much greater and deeper stimulative and therapeutically

beneficial effect.

>>>>>>>

All the LED studies have been with very weak sources and i mean very week. Also

most have been with visible light not infrared.The comparison is apples to

oranges. Only bales has done some work with stronger infrared LEDs. According to

him the studies at NASA do not show any difference in tissue penetration. The US

navy is finding that LEDs work great in their research. They are restoring

vision animals blinded by chemicals. There is a lot of commercial interests out

there and it is very difficult to get reliable information. All i can comment on

is my experience.

Oakland, CA 94609

August 28, 2005

ven on the web sites of the leading LED light devices, the sources and

references they list are not for LED therapy, but rather for laser light

therapy. Manufacturers of such devices as Bioflex, Anodyne and the Dynatron

Solaris units, which are LED therapy devices, primarily use laser light studies

as their medical efficacy support.

>>>>>>>

Phil almost all of these units put out such a weak output it would only be fair

if compared to cheep over the counter laser pointers. The site you got these

from are from a manufacturer of a laser. What about all the negative clinical

studies on lasers. There is just not enough reliable information out there.

If you ever in the bay area come and take a look at the changes seen in

thermography when the high powered LEDs are used.

Oakland, CA 94609

August 28, 2005

I will try to get Bales to add to the list, but not sure he will take the time

Here is some info on LEDs.

BACKGROUND AND OBJECTIVE: This study assessed the effects of optic stimuli

emitted by three different light sources on head skin blood flow. MATERIALS AND

METHODS: The irradiation effects of the He-Ne laser (632.8 nm, 10 mW, total

energy appr. 9.4 J), the InGaAl diode laser (670 nm, 60 mW, appr. 108 J) and

monochromatic light (635 nm, 112.5 mW, appr. 202.5 J) were measured using laser

Doppler technology. The corresponding fluences (energy densities) varied from

0.01 J/cm2 (He-Ne) to a range of 0.12-0.72 J/cm2 (InGaAl) and 0.22-1.36 J/cm2

(LED). The investigation was completed under single-blind, placebo-controlled

conditions where the subjects (10 male healthy volunteers) were exposed on two

occasions to the placebo (LED)-device against the laser (He-Ne or InGaAl).

RESULTS: A short lasting vasodilation, a 54 per cent increase (p < 0.05) in skin

blood flow was seen after the InGaAl irradiation (fluences between 0.12-0.36

J/cm2) whereas the non-coherent monochromatic irradiation (0.68-1.36 J/cm2) used

in this particular study decreased blood flow by 36 per cent (p < 0.05). The

He-Ne irradiation (0.01 J/cm2) had no effect. Skin temperature changes were

insignificant. CONCLUSIONS: Skin blood flow changes seemed to be related more on

radiant exposures then coherency.

From NASA

Title:

LED-array light source for medical therapy

Authors:

Schlager, Kenneth J.; Ignatius, Ronald W.

Affiliation:

AA(Biotronics Technologies, Inc.) AB(Quantum Devices, Inc.)

Journal:

Proc. SPIE Vol. 1892, p. 26-35, Medical Lasers and Systems II, David M.

Harris; Carl M. Penney; Abraham Katzir; Eds. (SPIE Homepage)

Publication Date:

07/1993

Origin:

SPIE

Abstract Copyright:

Downloading of the abstract is permitted for personal use only.

Bibliographic Code:

1993SPIE.1892...26S

Light emitting diode (LED) array light sources currently in development

offer an alternative to laser light sources in a wide range of medical

applications. Previously developed as light sources for research in

photosynthesis in plant growth experimentation, LED arrays have produced an

average continuous output of 4 - 6 watts at a wavelength of 660 nm. This output

is equivalent to the terrestrially sensed output of the sun at this wavelength

at high noon. LED chips are arrayed on an alumina tile substrate that may be

formed to provide optical power focused on a specified target area

Novel applications of high-brightness LED in

biomedicaltechnology-development of photodynamic therapy of leukemia by LED

Abstract

Light irradiation onto leukemia cells by LED were performed at 37 °C using

several sets of BIOLED placed in a CO2 incubator under a fixed light intensity.

We investigated the effect of light wavelength on the cell division.

Irradiations onto cells were done for two kind of culture media: (1) with an

addition of metal porphyrin which is used in photodynamic therapy (PDT) of

cancers, and (2) without any additive

LIGHT THERAPY FOR SEASONAL AFFECTIVE DISORDER WITH 470 NM NARROW-BAND

LIGHT-EMITTING DIODES (LEDs)

B Byrne, G Glickman, C Pineda, GC Brainard - apollolight.com

.... Conclusions Light therapy via a 470 nm LED array appears to be an effective

treatment

for subjects with major depression with a seasonal pattern. .

ABSTRACT

Recently, the LED (light emitting diode) developed by the Optics Group of

IFSC-USP has been used instead of laser for the treatment of skin tumors by the

PDT (Photodinamic Therapy) because of its low operational cost compared to the

use of a laser. In this paper we investigate the effect of LED light on

oxidative phosphorylation during liver regeneration after partial hepatectomy.

Twenty-four male Wistar rats (250 g) were kept in identical housing units on a

12-hour light/12 hour dark cycle. The LED 10 group was exposed to LED at 638 nm

(10 J/cm2 for 3 minutes). Seventy percent partial hepatectomy was performed in

the LED 10 and HPC (Partial Hepatectomy-Control). A sham-operated group © was

used for control. Twenty four hours after the procedure, LED 10, HPC and control

animals were sacrificed. Samples of liver tissue were used for the mitochondrial

respiration assay. Statistical comparisons of the groups were performed by

analysis of variance (ANOVA), followed by the Bonferroni post-test. Probability

values less than 0.05 were considered to be statistically significant. the

phosphorylation index (FI) for the LED 10 group was higher than that for the HPC

group and for the sham group (p<005). The FI for the HPC group was higher than

that for the sham group (p<005). The values of the ADP:O ratio for the three

groups, which did not differ significantly from one another (p > 0.05). In the

present study we noted an effective interaction between LED light and hepatic

mitochondria, with an increased phosphorylation rate for the latter. Available

from: URL: http://www.scielo.br/acb

Lasers in Surgery and Medicine

Volume 36, Issue 2 , Pages 85 - 91

Published Online: 14 Jan 2005

2005 Wiley-Liss, Inc., A Wiley Company

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Abstract | References | Full Text: PDF (351k) | Related Articles

Research Article

Clinical trial of a novel non-thermal LED array for reversal of

photoaging: Clinical, histologic, and surface profilometric results

Robert A. Weiss, MD 1 *, David H. McDaniel, MD 2, Roy G. Geronemus,

MD 3, Margaret A. Weiss, MD 1

1Maryland Laser Skin & Vein Institute, Hunt Valley, Maryland;

Assistant Professor of Dermatology, Johns Hopkins U School of Medicine,

Baltimore, Maryland

2Laser Skin & Vein Center of Virginia; Assistant Professor of

Clinical Dermatology and Plastic Surgery, Eastern Virginia Medical School,

Virginia Beach, Virginia

3Laser & Skin Surgery Center of New York; Clinical Professor of

Dermatology, New York University Medical Center, New York, New York

email: Robert A. Weiss (rweiss)

*Correspondence to Robert A. Weiss, Director, Maryland Laser Skin & Vein

Institute, LLC, 54 Scott Adam Road, Hunt Valley, MD 21030.

This data was presented in abstract form at annual meetings of ASLMS in

2002, 2003, and 2004.

R.A.W., D.H.M., and M.A.W. have disclosed potential financial conflicts of

interests with this study.

Keywords

light emitting diodes . photorejuvenation . light therapy . laser .

skin rejuvenation . pigmentation

Abstract

Background and Objectives

Photomodulation has been described as a process which modifies cell

activity using light sources without thermal effect. The objective of this study

was to investigate the use of a non-thermal low dose light emitting diode (LED)

array for improving the appearance of photoaged subjects.

Study Design/Materials and Methods

This prospective study investigated a random cohort of patients (N =

90) with a wide range of photoaged skin treated by LED photomodulation® using a

full panel 590 nm non-thermal full face LED array delivering 0.1 J/cm2 with a

specific sequence of pulsing. Subjects were evaluated at 4, 8, 12, 18 weeks and

6 and 12 months after a series of 8 treatments delivered over 4 weeks. Data

collected included stereotactic digital imaging, computerized optical digital

profilometry, and peri-ocular biopsy histologic evaluations for standard stains

and well as collagen synthetic and degradative pathway immunofluorescent

staining.

Results

Digital imaging data showed a reduction of signs of photoaging in

90% of subjects with smoother texture, reduction of peri-orbital rhytids, and

reduction of erythema and pigmentation. Optical profilometry showed a 10%

improvement by surface topographical measurements. Histologic data showed

markedly increased collagen in the papillary dermis of 100% of post-treatment

specimens (N = 10). Staining with anti-collagen I antibodies demonstrated a 28%

(range: 10%-70%) average increase in density while staining with

anti-matrixmetalloproteinase (MMP)-1 showed an average reduction of 4% (range:

2%-40%). No side effects or pain were noted.

Conclusions

Photomodulation to reverse photoaging is possible with a specific

array of LEDs with a specific fluence using a precise pulsing or code sequence.

Skin textural improvement by digital imaging and surface profilometry is

accompanied by increased collagen I deposition with reduced MMP-1 (collagenase)

activity in the papillary dermis. This technique is a safe and effective

Wiley-Liss, Inc.

Novel LED array used for photodynamic therapy (PDT)

Steven R. Daly, Frank Zheng, Mike Krouse, Zihong Guo, Paula Mahoney, and Brian

W. McIlroy

Light Sciences Corp. (USA)

(published online Oct. 17, 2003)

Light Sciences Corporation has developed a novel LED array that was designed and

manufactured to treat large bulky tumors. We describe our LED design process,

culminating in the manufacture of a flexible silicone catheter currently under

investigation in a Phase 1 clinical trial. The performance characteristics of

the wire-bonded die to a flexible polyimide substrate forming a linear array are

discussed. The LED array consists of 100 die arranged asymmetrically on the

substrate with 50 LED's on either side producing up to 60mW total optical power

at 38°C (500mA) over a spectral bandwidth 645-670nm FWHM. The LED's are

encapsulated within biocompatible silicon for interstitial placement within the

treatment tissue. The effect of time, temperature and humidity on the device

performance was investigated. Optical power ranged from -2.5% to +0.5% of the

normalized original power over 50 hours in 100% RH within the control group.

Over a temperature range of 35°C to 50°C the optical power decreased at a rate

of 0.56% per °C. Preliminary non-clinical experiments carried out in normal

swine muscle demonstrate a significant treatment zone and are consistent with

threshold models for photodynamic effect.

Downloading of the abstract is permitted for personal use

Journal of Clinical Laser Medicine & Surgery

Polychromatic LED Therapy in Burn Healing of Non-diabetic and Diabetic Rats

Oct 2003, Vol. 21, No. 5: 249-258

Farouk A. H. Al-Watban, MSc, PhD

Laser Medicine Research Section, Biological and Medical Research Department,

King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.

Bernard L. Andres, RMT, MT(AMT)

Laser Medicine Research Section, Biological and Medical Research Department,

King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.

Objective: We determined the effect of polychromatic light-emitting diodes (LED)

in burn healing of non-diabetic and streptozotocin-induced diabetic rats.

Background Data: LEDs were used as the light source for phototherapy. Materials

and Methods: The polychromatic LED is a cluster of 25 diodes emitting photons at

wavelengths of 510-543, 594-599, 626-639, 640-670, and 842-879 nm with 272-mW

output power. Age-matched, male Sprague-Dawley rats (n = 30) were used.

Streptozotocin (70 mg/kg) was used for diabetes induction. Rat weight,

hyperglycemia, and glycosuria were monitored for the first 3 days and weekly

thereafter. Rats were anesthetized and shaved after 1 week of diabetes. Burn

areas of 1.5 ± .03 cm2 were created using a metal rod pre-heated up to 600°C

that was applied for 2 sec. Diabetic and non-diabetic rats were randomized into

the following treatment groups: control, 5, 10, 20, and 30 J/cm2. Light

treatment commenced after burn infliction and was repeated three times per week.

Burn areas were measured daily. Results: Burn healing was impaired significantly

during diabetes by -46.17%. Polychromatic LED treatment using 5, 10, 20, and 30

J/cm2 incident doses influenced healing by 6.85%, 4.93%, -4.18%, and -5.42% in

the non-diabetic rats; and 73.87%, 76.77%, 60.92%, and 48.77% in the diabetic

rats, relative to their controls, respectively. Conclusion: The effect of

polychromatic LED in non-diabetic rats was insignificant; however, it simulated

the trend of stimulation and inhibition seen using low-level lasers. Significant

stimulation observed in the diabetic rats demonstrated the usefulness of

polychromatic LED in diabetic burn healing.

Abstract

There is no uniformly accepted objective method to diagnose the functional

extent of retinal damage following laser eye injury and there is no uniform

therapy for laser retinal injury. J.T. Eells, et al, reported the use of Light

Emitting Diodes (LED) photoillumination (670 nm) for methanol-induced retinal

toxicity in rats. The findings indicated a preservation of retinal architecture,

as determined by histopathology and a partial functional recovery of

photoreceptors, as determined by electroretinogram (ERG), in the LED exposed

methanol-intoxicated rats. The purpose of this study is to use multifocal

electroretinography (mfERG) to evaluate recovery of retinal function following

treatment with LED photoillumination in a cynomolgus monkey laser retinal injury

model. Control and LED array (670 nm) illuminated animals received macular Argon

laser lesions (514 nm, 130 mW, 100 ms). LED array exposure was accomplished for

4 days for a total dose of 4 J/cm2 per day. Baseline and post-laser exposure

mfERGs were performed. mfERG results for five animals post-laser injury but

prior to treatment (Day 0) showed increased implicit times and P1 waveform

amplitudes when compared to a combined laboratory normal and each animal's

baseline normal values. In general, preliminary mfERG results of our first five

subjects recorded using both the 103-hexagon and 509-hexagon patterns indicate a

more rapid functional recovery in the LED illuminated animal as compared to the

control by the end of the fourth day post-exposure. Research is continuing to

determine if this difference in functional return is seen in additional subjects

and if statistical significance exists.

Oakland, CA 94609

August 28, 2005