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Marry Dyson PhD - Beurer SL-30 Clinical Study
Mary Dyson PhD, FCSP
Emeritus Reader in the Biology of Tissue Repair, Kings College London, UK; Former Professor, Department of Physical Therapy & Rehabilitation Sciences, University of Kansas Medical Center, Kansas City, USA.
Red light delivered by low intensity lasers, has been used to stimulate tissue repair for over 30 years. Its uses now include the alleviation of a range of skin conditions including
Acne (Hirsch and Shalita, 2003)
Scarring (Patel and Clement 2002)
Skin deterioration due to aging and sun damage (Alam & Dover, 2003)
All these conditions involve tissue injury, sometimes acquired over many years. Their improvement is achieved by tissue repair, which can be initiated and stimulated by exposure to low intensities of red light and to some other forms of electromagnetic radiation such as infrared (IR) radiation. Exposure to red light increases blood flow to the skin thus improving its metabolism, and stimulates the manufacture of collagen, the protein that gives strength to the skin (Bjerring et al 2002). Other uses of red light include accelerating the resolution of inflammation (Dyson 2004) and the reduction of pain (Moore et al 1988).
The laser technique used to deliver this light is usually termed low level laser therapy (LLLT), also referred to as low intensity laser therapy (LILT), low energy photon therapy (LEPT) and phototherapy. Unlike the high intensity medical lasers used to cut and coagulate tissues, LLLT involves the use of medical lasers such as the Beurer SoftLaserTM that operate at intensities too low to damage living tissues. Unlike most LLLT devices that are relatively large and designed for clinical use, the Beurer SoftLaserTM is a small, hand held, device designed for home use.
Light consists of those wavelengths of the electromagnetic spectrum that are visible to the human eye. This part of the spectrum extends from violet (the shortest visible wavelength) to red (the longest visible wavelength). Infrared (IR) is just beyond the visible range. The perceived colour depends on the wavelength. White light is a mixture of all the visible wavelengths. For photons to reach the skin, all that is required is that it be either exposed to air or, if injured, to be covered by a transparent dressing. Exposure to red light and/or infrared radiation can stimulate the healing of both chronic injuries of the skin (Mester et al 1985) and acute injuries (Dyson & Young 1986).
This is an acronym for Light Amplification by the Stimulated Emission of Radiation. The stimulated emission of radiation occurs when a photon interacts with an energized atom. When an atom is energized, for example by electricity, one of its electrons is excited, i.e. raised to a higher energy orbit than its orbit when in the resting state. If the energy of the incident photon is equal to the energy difference between the electron’s excited and resting states, then stimulated emission of a photon occurs and the excited electron returns to its resting state. This photon has the same properties as the incident photon, which it also emitted. This process is repeated in the adjacent energized atoms, producing a laser beam. Unlike light from non-laser sources, this light is:
Monochromatic, i.e. of a single wavelength
Collimated, i.e. its light rays are non-divergent
Coherent, i.e. in phase, the troughs and peaks of the waves coinciding in time and space.
With regard to the biomedical effects of LLLT, monochromaticity is its most important characteristic. To produce an effect, the light must be absorbed, and absorption is wavelength-specific. Different substances absorb light of different wavelengths. Mitochondria, present in all mammalian cells except erythrocytes, contain cytochromes that absorb red light.
This has three essential components:
Lasing medium, which is capable of being energized sufficiently for lasing to occur
Resonating cavity containing the lasing medium.
Power source that transmits energy into the lasing medium.
The type of lasing medium used determines the wavelength, and therefore the colour, of the laser beam. For example, a HeNe laser, in which the lasing medium is a mixture of helium and neon gases, produces red light with a wavelength of 632.8 nm. Gallium, aluminium and arsenide, the lasing medium of GaAlAs semiconductor diodes, also produces monochromatic radiation, but the wavelength of this depends on the ratio of these three materials and is in the red-infrared range of the electromagnetic spectrum, typically 630-950 nm.
The resonating cavity containing the lasing medium has two parallel surfaces, one being totally reflecting, the other being partially reflecting. Photons emitted from the lasing medium are reflected between these surfaces, some of them leaving through the partially reflecting surface as the laser beam. The cavity of a HeNe laser is many cms long, whereas that of a GaAlAs semiconductor diode is tiny, the diode being the lasing medium and its polished ends the reflecting surfaces. Modern low intensity laser therapy devices are generally of the GaAlAs type. Their treatment heads may contain either one or several diodes. Those with one diode resemble laser pointers and are designed to treat acupuncture and trigger points; they can also be used to treat points in and around skin injuries. Those with many diodes are generally called cluster probes and allow large areas to be treated rapidly. The diodes may be housed in a rigid head or in a flexible material. The latter can be applied around curved surfaces such as the shoulder. Each diode emits either red or IR radiation. Red light is absorbed by all cells, whereas different wavelengths in the infrared range appear to target specific cell types.
The power source for a LILT device may be either a battery or mains electricity. Many LILT devices are portable. The main function of the power source is to energize the lasing medium.
The Beurer SoftLaser TM
This hand-held LLLT device is a low level Class 3A laser manufactured in Germany by Beurer GmbH. It has a single probe containing a 5 mW GaAlAs diode producing red light of 635-670 nm wavelength. It is powered by 2 AAA batteries.
Application of SoftLaserTM to skin
The probe is placed in contact with clean skin at right angles to the skin’s surface and moved slowly over the region to be treated for a few minutes, typically 3-6 minutes for a region of about 1 cm diameter. A convenient way to use it is twice daily, shortly after cleansing the skin in the morning and evening, and before the application of a moisturizing cream and/or cosmetics.
LLLT EFFECTS ON DAMAGED SKIN
Effects of the Beurer SoftLaserTM on skin
The Beurer SoftLaserTM has been found by its users to:
Make scars less visible
Tighten large pores
Elevate pock marks
Improve skin tone
Give a temporary radiance to the skin
Soften chapped lips.
Treatment of damaged skin with red light accelerates the resolution of inflammation, leading to faster repair (Dyson 2004). The stimulated secretion of collagen by fibroblasts at the site of a wrinkle or of a pock mark will increase the thickness of the dermis locally, helping to fill in the tissue deficit. The gradual removal of excessive scar tissue may be due to the activation of fibroblasts, fibrocytes and other cells in and around the scar.
As with any other technique, tissue repair can only be stimulated by LLLT if it is absent or delayed. In these circumstances, epithelialisation and granulation tissue production can be stimulated by LLLT as can wound contraction (Dyson & Young 1986) This reduces the area in which scar tissue is produced resulting in less obvious scarring.
HOW LLLT PRODUCES ITS EFFECTS
For LLLT to be effective, the tissue targeted must absorb photons. Absorption is wavelength dependent. Red light is absorbed by cytochromes in the mitochondria; all human cells, other than mature red blood cells (erythrocytes) contain mitochondria. Provided that appropriate wavelengths and energy densities are used, cell activity can be stimulated if it is suboptimal. Cells in which this has been investigated include mammalian keratinocytes, lymphocytes, macrophages, mast cells, fibroblasts and endothelial cells, all cells of significance in tissue repair. Much of the research on this has been reviewed by Baxter (1994) and by Tuner and Hode (2002). Cells affected by LLLT show a temporary increase in permeability of their cell membranes to calcium ions (Young et al 1990). This may be an important component of the mechanism by which LLLT modulates cell activity; other electrotherapeutic modalities, such as ultrasound, may act in a similar fashion (Dyson 2004).
The triggering of cell activity by reversible changes in membrane permeability when photons are absorbed could be responsible for the stimulation of tissue repair (Young & Dyson 1993). Increase in calcium uptake by macrophages exposed to red light and IR in vitro has been shown to be wavelength and energy density dependent. Of the wavelengths tested, 660, 820 and 870 nm were effective; 880 nm was ineffective. These same wavelengths also affected growth factor production by the macrophages, 660, 820 and 870 nm being stimulatory, whereas 880 nm was not. Energy densities of 4 and 8 J/cm2 were found to be effective; 2 and 19 J/cm2 were not (Young et al 1990). Red light of 660 nm wavelength is absorbed by the cytochromes of mitochondria, where it stimulates ATP production and increases cytoplasmic H+ concentration, which can affect cell membrane permeability (Karu 1988). IR radiation of 820 and 870 nm may be absorbed by components of the cell membrane. Some of these components vary in different cell types, which may be why the IR wavelengths absorbed by cells differ according to the cell type. For example, 870 nm affects macrophages (Young et al 1990) but not mast cells (El Sayed & Dyson 1990). It may be possible to selectively stimulate macrophages but not mast cells in vivo by exposure to an 870 nm probe.
Following a reversible change in membrane permeability to calcium ions, the cells respond by doing what they are programmed to do. In the case of macrophages, this is to produce growth factors and to phagocytose debris, whereas fibroblasts manufacture collagen and other extracellular components of the dermis.
The molecular mechanisms by which LLLT affects cell activity begin with photoreception, when the photons are absorbed. This is followed by signal transduction, amplification and a photoresponse, e.g. cell proliferation, protein synthesis and growth factor production, all of which may assist in tissue repair. Membrane structure differs according to the cell type, which, if IR is absorbed by parts of the membrane, may explain why different cell types absorb different wavelengths of IR. Theoretically, it should be possible by the judicious selection of IR wavelengths to affect some cell types while leaving others unaffected. In contrast red light, since it is absorbed by the mitochondrial cytochromes present in all mammalian cells other than erythrocytes, and also by the hemoglobin contained in erythrocytes, affects all mammalian cells.
HOW LLLT PRODUCES ITS EFFECTS
Cellular effects relevant to skin repair
The cellular effects of LLLT relevant to skin repair include the stimulation of
adenosine triphosphate (ATP) production
growth factor release by macrophages
All of the above are required for skin to renew itself and repair the damage done to it by, for example, environmental factors such as excessive exposure to the elements, damage that accumulates with age.
Temporary vasodilatation following the exposure to red light improves the transport of essential nutrients and oxygen to the skin and the removal of toxic waste materials from it. It also gives sallow skin a radiant glow.
PAIN RELIEF BY LLLT
Although many of the reports of pain relief following exposure to LLLT are anecdotal, there have been a number of reports based on trials aimed at assessing LLLT as an antinociceptive or analgesic modality, one of the earliest being that of Walker 1983 who implicated alteration in serotonin metabolism as one mechanism of LLLT-mediated analgesia.
Walker et al (1987) reported a highly significant reduction (p<0.001) in the levels of pain and analgesic medication intake reported by rheumatic patients either treated with low intensity red laser or sham-irradiated, pain relief being greater in those given laser treatment. Palmgren et al (1989) found that treatment of the small joints of the hand in rheumatic patients with low intensity infrared laser was followed by reduced pain and swelling, reduced early morning stiffness and increased grip strength and range of movement. In contrast Basford et al (1987) found that red laser irradiation of the osteoarthritic thumbs of patients was not followed by significant reduction in pain; however, the power and energy levels used (0.9 mW and 0.081J) are well below those recommended for clinical application (Baxter 1994) and may have been sub threshold.
Chronic neurogenic pain
Moore et al (1988a) have investigated the effect of red laser in the treatment of patients with chronic neurogenic pain including that of post-herpetic neuralgia. It was found that there was a significant reduction in reported pain following treatment in comparison to that in sham-irradiated patients. Similar effects have been reported by Hong et al (1990) using the same equipment.
It has been suggested by Obata et al (1990) that laser-mediated relief of rheumatic pain may be linked to autonomic changes that produce vasodilatation and slight increases in local temperature. It is also possible that laser treatment affects the synthesis, release and metabolism of a range of neurochemicals involved in nerve transmission and pain relief (Walker 1983). Relief following the stimulation of acupuncture points with LILT has been ascribed to the production of endogenous opiate-like peptides and serotonin by Zhong et al (1989).
Scarring associated with acne and skin deterioration due to ageing and sun damage can be alleviated by LLLT. These skin conditions involve tissue injury, the repair of which is improved by exposure to LLLT in the form of red light. LLLT can reduce the duration of inflammation, improving tissue repair where this is delayed or defective. It can also reduce both acute and chronic pain. By assisting in the resolution of inflammation, the proliferative phase of tissue repair begins earlier and the reparative process is completed earlier. Cell activity is jump-started by changes in membrane permeability. This occurs when the cells absorb red and/or infrared radiation. The cells are also energized when red light is absorbed by their mitochondria, stimulating the synthesis of ATP and thus providing readily available energy for cell activity. The improvement in the skin produced by LLLT has been described as skin rejuvenation (Lee 2002). The Beurer SoftLaserTM takes LLLT from the clinic into the home where it can be used regularly for skin care.
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