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The Light Fantastic: Photobiology and Light Emitting Diodes
By: Erin Madigan-Fleck
Posted: January 31, 2014, from the February 2014 issue of Skin Inc. magazine.
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The first law of photochemistry is that light must be absorbed from a particular wavelength for it to interact with tissue. Each photon of light absorbed by a chemical system in the body is responsible for initiating only one molecule. Both visible red and infrared (IR) wavelengths are able to adapt the mechanisms of epidermal keratinocytes to increase localized blood flow. This has positive effects on oxygenation and the transfer of nutrients to the area treated. Furthermore, the wavelength-specific output of 630–670 nm raises the potential of macrophages, fibroblasts and keratinocytes, as well as anti–inflammatory and immune-supportive effects.2, 4, 5
The 660–680 nm red wavelength appears to be the most effective. It is closer to the actual resonance frequency of the healthy cell, providing the stimulation of adenosine triphosphate (ATP), thus reducing the vulnerability of nerve tissue, and triggering positive ions and minerals to the site of treatment.
The orange-red range of 560–780 nm is most effective for skin rejuvenation treatments that relate to the rehabilitation of the microcirculation and encouragement of fibroblast activity. Far infrared, often used in conjunction with LED, has the ability to release nitric oxide from blood and endothelial cells, thus activating enzymes to encourage vasodilatation, allowing for a more rapid wound-healing.6, 7 (See LED Colors and Treatments.)
Selecting an LED device
The key to selecting a LED device lies in the identification of the nanometer range and the quality of the device. As the market features a plethora of “red light therapy” instruments, skin care professionals should consider high-quality vs. price. A hand-held modality should position easily over the treatment area, supplying adequate coverage of LED illumination. Other considerations are the size of the handpiece or panel, and the quantity of actual LED diodes. For a detailed application, a LED pen, included on many devices, is beneficial when a focal point of light delivery is desired. It is important to note that the distance the diodes are positioned from the client will impact the overall treatment in regard to penetration of therapeutic delivery.
Many esthetic equipment vendors indicate that a desirable level of treatment may be achieved with a hand-held device positioned for approximately 90 seconds per treatment section, making four passes. Panel devices generally offer more coverage due to the size of the panel and increased number of LED diodes. The frequency of the LED application depends on many variables, such as desired results and other esthetic considerations; however, the general consensus is that no matter the type of device, successful treatments require:
- Proper selection of the LED color and nanometers specific to the condition;
- Proper timing sequence per session and frequency of treatment;
- Client compliance; and
- Proper product and home-care recommendations.