Some might question how something as simple as light can have such a profound biological effect. However, the biological importance of light has been recognized for quite some time.
Sunlight absorbed by chloroplasts in plant cells permits formation of starch. Sunlight absorbed by human skin generates vitamin D. Some wavelengths of light, including near infrared and ultraviolet (UV) light cannot be seen with the human eye, and yet cause biologic effects.
Mainstream knowledge of infrared light LED technology developed in response to experiments conducted by NASA in the early 1990's. Now, there are many types of infrared and laser therapy devices.
In theory, these devices work under the same principles and laws of physics. However, their differences lie in terms of their methods (wavelength, pulse rate, intensity, etc.), design (total surface area) and their application (handheld or attachable).
Light Emitting Diodes (LEDs) vs Lasers
Lasers deliver collimated, coherent light. This simply means that the infrared light is focused in a column and does not disperse as much over the treatment area. Lasers are monochromatic by definition, which means they emit infrared light at one wavelength.
A light emitting diode (LED) is a semi-conductor device that emits incoherent narrow-spectrum light. Some LED devices are also monochromatic, such as Anodyne® Therapy Systems.
Infrared Light from both lasers and LEDs disperse once the light contacts body tissue. The depth to which they penetrate has nothing to do with whether the light is lased, but rather has to do with the wavelength and energy density.
Infrared Light output from LEDs possess all the attributes of laser radiation except coherence. Findings at the cellular level would imply that the property of coherence is largely unnecessary for the clinical effects of these devices.
At a particular wavelength, light that is emitted out of a LED or a Laser will have similar clinical effects on body tissue. Effects can be further enhanced by increasing the surface area of treatment device, and by increasing the energy density.
Lasers are usually enclosed behind glass and recessed a few centimeters; where as the LEDs
of Anodyne® Therapy Systems are in direct skin contact.
contact minimizes the amount of light refracting off of the
skin, thus increasing the amount of light absorbed by the blood
Over the years, some wavelengths of infrared light have been proven to be more effective than other wavelengths in terms of increasing circulation. The wavelength of 890 nm that is used with Anodyne® Therapy Infrared Products has been validated through our published clinical data, and also through independent testing.
Visible red, blue or green light has not been proven in any clinical evaluations to be effective in increasing circulation or decreasing pain. Devices that have both infrared and visible colored lights can not be as effective as those with all infrared light diodes.
The video below is that of a human hand with an Anodyne® Infrared Therapy Pad placed on the palmar aspect. You can see the light passing through the cracks of the fingers, as well as through the skin. However, you can see that the blood vessels are very dark, which means that the light is not passing throug, indicating that it is being absorbed within the blood vessels.