The purpose of this article is to introduce laser newbies to the concepts of wavelength as an important operating parameter in cold lasers, PBM and laser therapy. Each of the wavelengths used in therapy lasers interacts with tissue in a unique way. Near the end of this article we will analyze the overall therapy laser market to see some trends from the 25+ cold laser manufacturers and make some summary conclusions.

Part 1 - The importance of wavelength

The Optical or Therapeutic Window

The following graph is republished from the book Laser Field Therapy by Anja Fuchtenbush, Volmar Kriesel and Peter Rosen. Variations of this graph are used across the web. This graph shows the absorption of light into different component of the human body. In this graph, we can see a low valley in the center of the range where the light can travel the greatest distance. This is the optical window and it ranges from 650nm to 900nm and you can also see that the high-end extends up to about 940nm. There is a lot of literature emphasizing the optical window and how it is used to predict the best wavelength for therapy lasers. Recent developments show that each wavelength has advantages but 650nm to 900nm is the best wavelength because it has the best combination of depth of penetration (low absorption), cellular interaction and energy transfer efficiency.

optical window

RED (600 to 660nm)

Much of energy from red wavelength interacts with melanin (near the surface) and with the hemoglobin in the blood. There is also a reaction with mitochondria (secondary peak of the Cytochrome C Oxidase curve). This energy is absorbed close to the surface making it the best option for superficial issues like scar tissue, burns, cosmetic issues and other shallow issues. It can also be successfully used to treat neuropathy because the pain sensors associated with neuropathy are close to the surface.

Because some of the energy in this wavelength is transferred in the blood stream (but not hemoglobin), this wavelength can also be used to treat more complex problem where the exact treatment location might be unknown. This wavelength is also good for treating the lymph system and acupuncture points.

Near Infrared (760 to 860nm)

The most important wavelength for PBMT is in the range of 760 to 860nm with the peak around 808/810nm. This is one of the best wavelength to get a combination of deeper penetration and cellular interaction. Laser in this range are the optimized to interact with deep cells mitochondria and they trigger an increase in Cytochrome C Oxidase and Adenosine Triphosphate, 2 key chemicals critical in the PBMT. About 70% of the therapy lasers on the market operate in this range. Several studies have shown unbelievable results in experiments with rats in the regeneration of damaged tissue in this range[1].

905nm

Most 905nm lasers are "superpulsed". Multiradiance has championed this wavelength so successfully that it has become somewhat of a standard in multi-wavelength systems. Laser diodes in this range are usually pulsed (turned on and off) to keep the diode. This wavelength is also very popular because "superpulsing" the laser reduces the risk of eye damage. This wavelength is unique because it interacts primarily with the iron in hemoglobin. When a 905nm laser interaction with the iron in hemoglobin, it oxygenates the area. Oxygen is another key chemical in the healing process so that some conditions might get the best result with a super-pulsed laser. This is the most common wavelength for home systems because they are the safest.

980nm

As we near 980nm, we are outside of the optical window and we are approaching the peak interaction of light with H2O in the body. At the wavelength increases, it approaches 100% absorption by water. Although some of the energy is also interacting with the tissue and performing the same function as a 800 to 850nm laser, the bulk of the energy goes to creating thermal gradients in the H2O that increase circulation and blood flow. The increase in circulation may help with tissue relaxation. This is also the most popular wavelength for high-end pain control lasers and many doctors feel that 980nm system provide the highest level of pain control. If you would like to see the downside to 980nm, just search for "980nm surgical lasers" and will see how they market 980nm system as great for surgery because so much of the energy converts into heating water in tissue. The big issue here is that any energy that is converted into heat cannot be converted into chemical energy (which is the main goal of PBM). For this reason, we only recommend 980nm as a secondary wavelength for people who also want maximum pain control, maximum circulation and better muscle relaxation.

1064+ nm Lasers

Similar to lasers in the 980nm, 1064 and up are more wavelengths that are less affective at driving energy deep into tissue and triggering a photochemical reaction but they are better for pain control, inflammation control and increasing blood flow.

 

Is There One Magic Wavelength?

Small variation in wavelength of a therapy laser don't matter. Some manufacturers say one single wavelength is superior and other similar wavelengths within the manufacturing tollerance of the diodes are less effective. If you study specifications for laser diodes, you will typically see that "810nm" diode can range from 800nm to 830nm based on the chemical composition of the diode so it is questionable to says that any single wavelength is significantly better if they are both within the tolerance of standard laser diode manufacturing.

The actual output wavelength is also based on the temperature of the diode. The output change for a typical IR diode is 0.3nm/oC so the wavelength when you first turn a system on (20oC) will be 3 to 10 nanometers less than it would be at the full operating diode temperature (up to 40oC). This also shows that any manufacturer that is saying a single wavelength is superior is probably over-marketing.

Emphasis on the higher NIR wavelengths and deeper penetrations are echoed by a majority of cold laser manufacturers. Although each manufacturer insists that their wavelength is optimal, there is no general consensus on the sweet spot other than 780nm to 830nm . For some specific conditions, the lower wavelengths are best and sometimes a higher wavelength is best. Having a system that is capable of multiple wavelengths gives you the most flexibility.

Multiple Wavelengths at the Same Time

Another debate is the idea of using multiple wavelengths at the same time. Is it better to treat with one wavelength at a time or multiple bands at the same time? According to some manufacturers, like Multiradiance, TheraLase, Chattanooga and Lightforce, K-laser, EVOlaser, and Biophotonica the answer is multiple wavelengths create a synergy. One the other hand manufacturers, such as Thor, Avant, Apollo, Nexus and Laserex, support one wavelength at a time. In general, multi-wavelength systems give more of a shotgun effect by interacting with many different kinds of cells and in many different ways to produce the a variety of changes without the operator needing to worry about setup each wavelength.

Both concepts have their place:

  • Point and Shoot- If you would not go to the trouble to try and control the dosage for each wavelength, you are probably better with a multiwavelength shot-gun approach to treatment. You might only get 1% of the dosage you want at a specific wavelength but it is better than nothing.
  • Precision - If you care about dosage and want the best results, you need to control each wavelength independently so that you get the appropriate dosage for each wavelength.

In theory, it is better to treat each area with the optimum dosage (wavelength and total energy) if you have the time and training to determine the proper dosage. In the real world, combining the wavelengths simplifies the protocol, reduces the therapy complexity, reduces the treatment time and give patients at least some energy in the wavelength that might have the biggest impact.

200-400 (UV-A, B and C) are NOT Good for Therapy Lasers

There are some products that integrate UV light into their lasers because of its antibacterial properties but wavelengths below 400nm can disrupt the DNA so this range should be avoided. We do see some interest in therapy systems that are just outside of the UV range at 405nm to 450nm.

405-450nm (Violet to blue)

This is a very recent developement promoted by Erchonia and Avant. 405nm wavelength is just above the UV range so it holds some promise for having a antibacterial, antifungal and antiviral properties without the downside to UV.

Pink, Green and Yellow

Recently there are some consumer-targeted products from fringe manufacturers with other wavelengths like pink, green and yellow light. At this time, we have not been able to find much science behind the use of these wavelengths for cellular therapy. Fringe companies might be adding them to their product for differentiation. None of the more established and successful laser manufacturers used these wavelength because there is little science to justify them. You will typical see that the companies using these new wavelength also make some ridiculous claim about their product. These wavelength might someday be proven to be useful but right now, the are mostly marketing hype and it is foolish to pay more for a product with exotic unproven technology.

The Cold Laser Industry in Summary

The following summary table compares the wavelengths of various cold lasers. Some of products are $50,000 devices made by huge medical companies with big R&D budgets and some are made by small companies with limited budget. I have flagged the larger corporations so we can look the "elite" group after we review some of the "outliers".

Part 2 - Comparison

Manufacturer /Product

Primary Wavelength1

Notes

Popular Cold Lasers

Avant LZ30

808 nm + 637 nm , 405nm Optional

Wavelengths are not simultaneously

Multiradiance

910 nm main +

875 nm + 660 nm

Typically uses all wavelengths simultaneously but they are programmable on higher models.

Thor

810 nm, 660 options

Uses separate emitter heads so you never have simultaneous output

Apollo

810nm

Simple class-4

MedX

808nm laser 870nm LED

Priced under $2500

ML830

830 nm

Center LED Pointer

PowerMedic 808nm Pulsing Only

Theralase

905 main, 660 nm option Superpulsing like TerraQuant

Vetro Laser (Vet)

808nm

Veterinary, Minimal guide light

Laserex (Vet)

808nm

Other wavelengths available

Elite Lasers ($10K plus & desktop models)

K-Laser

635,800,910,980 nm options

Class 4

Chattanooga Vectra

670, 850, 880, 950nm options

LiteForce

980 (80%) and 810 nm (20%)blended

Unique roller emitter

EVOlaser 635,810,905,980 options Affordable high-end performance
Biophotonica 450,635,810,905,980,1064 options The ultimate is flexability

Outliers And Special Devices

Q1000

470-940nm

Consumer Product based on Soliton Wave Technology.

Scalar Wave

650 nm + 780 nm + Violet (400nm)

Consumer Product based on Quantum Wave Technology.

Laser Touch One

670nm

Consumer Product with Electrical Stim. Super low power.

Erchonia

635nm

Very low power.

Omega

660nm, 810nm, 850nm, 880nm or 940nm

Cleared for Smoking Cessation

1The primary wavelength is the wavelength with the most power.

Our criterion for determining if a product is an outlier is:

  • Products that do not operate using wavelengths used the majority of the practitioner-grade products.
  • Products designed mainly for the consumer market.
  • Products that are marketed with a unique technology like soliton, zero point energy or quantum waves

The goal of establishing outlier is not to punish these products but to establish a main stream for the overall practitioner-grade cold laser market.

As we can see, class 4 lasers (7 to 60 watt) are mostly 980nm while the class 3b lasers (fraction wattage) are typically 810nm. This crossover is totally based on cost. 980nm laser diode are also used in surgical lasers. The higher volumes has pushed down the cost that 980nm high power laser module is less than half the cost of a high power 810nm. 980nm systems have dominated the high-end market because they are more profitable for the manufacturers, not because they are better.

More Info about Wavelengths Used in Photomedicine

The following is some highlights about different wavelength and their uses from the “Handbook of Photomedicine” by Hamblin and Haung.


Section 2: Diseases caused by light
The 3 main wavelengths that can cause damage to tissue are:

  • UVC: 200-290nm - Mostly absorbed by the ozone laser so there is less evidence of diseases caused by UVC.
  • UVB: 290-320nm - Causes DNA damage. The major cellular chromophores that absorb in the UVB rangeĀ  are nucleic acids (DNA and RNA) and some proteins. Even though UVB can cause DNA damage, it is used to treat Psoriasis and other inflammatory skin disorders.
  • UVA: 320-400nm - The energy from the sun in the UVA range is about 1000 times less than UVB so there is less evidence to the potential for tissue damage.

Section 3: Photodynamic Therapy
Photodynamic Therapy (PDT) uses a photosensitizer (PS) that will accumulate in tumor tissue. Then the PS is activated using light and it becomes cytotoxic and can help destroy the tumor. The majority of this type of therapy is done in the 600nm to 800nm range. Here is a table to show some of the wavelengths that are also used in photodynamic therapy.

Photosensitizer

Activation Wavelength

Porphyrins

630nm

Chlorins

650nm -700nm

Bacteriochlorins

720nm - 800nm

 

Section 5: Surgical Lasers
The following is a summary chart from the surgical section of the book.

Treatment Type

Wavelengths Used

Notes

Pigmented Lesions

694nm(Ruby), 1064nm and 532nm (Nd: YAG), 755nm(Alexandrite),

Optimized to be adsorbed by the lesion

Tattoo Removal

Pulsed 694nm (Ruby), 755nm(Alexandrite), 1064nm and 532nm (Nd: YAG)

Optimized to be adsorbed by the tattoo pigment

Hair Removal

755nm(Alexandrite), 800-810nm, 1096nm, 590-1200nm (IPL)

Optimized to target dark hair

Facial Photoaging

10,600nm (CO2), 2930 - 2940nm (Er:YAG)

CO2 laser are the gold standard. Optimized to be absorbed by water

980nm and 1470nm diode surgical lasers can be used general surgery to Otolaryngology, Proctology, Thoracic surgery, Pneumology, Gynecology, Gastroenterology, Laparoscopic surgery, Vascular surgery, Dermatology, Neurosurgery, Urology, Oral and maxillofacial surgeries. While doing research on the other uses of different wavelengths of laser, we ran across the following statements from a 980nm surgical laser manufacturer (Surgical Laser Inc).

"Generally speaking, the greater the absorption, the greater the interaction, and in the case of biologic soft tissue, the 980nm high absorption diode laser targets WATER as water comprises > 70% of soft tissue. Higher water absorption means more efficient and effective ablation."

"With high absorption in both water and hemoglobin this wavelength is optimized for performance resulting in optimal tissue ablation, durable coagulation and enhanced visibility."

The first high power class 4 lasers were all 980nm and so that has become the standard for higher power systems. Over the years, 980nm has been incredibly successful at high-volume pain clinics and thousands of other institutions treating the most difficult cases. The manufacturers of these systems also recommend higher dosages than any other systems. It seems like these system are diverging from the core photobiomodulation group but the results speak for themselves. Tens of thousands of happy customers say that 980nm is a great wavelength for the toughest problems.

Summary

In conclusion, the wavelength of the light has a major impact on how the light interacts with tissue in the body. Although there is no one right answer, the general consensus is that:

  • The use of different wavelength emitters allows more flexibility in a treatment. Each wavelength can excite cells in a slightly different way giving a practioner, not one, but several different mechanisms to treat the same problem.
  • Infrared emitters in the 800 nm range are best for deep tissue work because they are not quickly absorbed by hemoglobin or water.
  • Many of the higher-end and most expensive products offer wavelengths in the 900nm range. These wavelenghts have proven results over many year of successful application.
  • Emitters in the 600 nm to 660 nm range are recommended for treating root nerve, acupuncture and trigger points. Red light is also useful as a guiding light when used in combination with infrared lasers.
  • There is no agreement in the cold laser industry on an exact wavelength that is best for healing.

In addition to wavelength, other factors that can be equally important to the effectiveness of cold lasers are power level, accuracy of the dosage, range of the protocols, and the size of the treatment area. Other factors to consider before purchasing a cold laser are the warranty period, build quality, device interface and of course, the overall safety of the product. In reality, it seems like all the cold lasers on the market have a unique value proposition (cost versus benefit) and they are all good at helping people with pain management and healing.

 

call

Send Us your Comments, Questions, Feedback and Suggestions

(* = Required, add your phone number for a faster response.)
Name*: Email*:
Phone:
Comment*:
5 + 4 =* This math problems stops most spam.