Wound healing impacts most medical and surgical specialties. Wound care accounts for a large healthcare expenditure every year, as wounds pose problems with morbidity, disability and mortality.
Therefore, new therapies are continually being explored. Dermatologists and cosmetic surgeons have a special interest in healing, given the number of wounds they create.
Lasers in wound healing were first studied more than 35 years ago. At that time the military and NASA had an interest in devices to speed healing in space, as well as during warfare.
Research with lasers in wound healing has been slow. Their use for wound healing was based primarily on a handful of anecdotal reports, and reports of cell stimulation in vitro. In addition to the skin, lasers have been used for wound healing in other tissues such as bone, gingiva and even muscle. Publications and banter regarding this controversial treatment lulled for nearly a decade, until recently when it has regained its popularity mainly, in part, due to the resurgence of light emitting diode (LED) devices on the market.
To improve healing, it's possible to envision the use of lasers in two ways.
The first is as a tool for debridement. This was first described using the carbon dioxide laser system for infected chronic wounds. Despite success, feasibility is questioned due to the pain associated with the laser process.
The second method of laser use in wound healing is via the properties of low level laser therapy (LLLT). LLLT consists of low power (milliwatt range) light emitting devices of variable wavelengths and variable pulse duration. This broad definition of LLLT is one of the inherent problems with analyzing the research done in this area. Technically speaking, a device in the LLLT category should emit a single coherent wavelength of light. Unfortunately, in the general press, several different devices are referred to as LLLT devices, though they are not true laser devices.
Light emitting diodes are sometimes included as LLLT. They have also been studied in wound healing and emit low power light.
However, they do not emit coherent, monochromatic light, but rather light of variable wavelengths. While this does not necessarily make them less effective, a distinction should be made between these different categories of devices. LEDs do have one advantage over true, low level laser devices in that they can treat large areas with a single exposure.
The best-studied LLLT devices for wound healing include the helium neon laser with a wavelength of 632 nm, the gallium aluminum laser and the gallium aluminum arsenide diode lasers with wavelengths between 780 nm and 910 nm. The newer noncoherent light emitting diode devices have similar wavelengths in the red to near infrared range, but less data exists. Neither the LLLT or LED device produce cellular damage. The energy density of the light emitted is very low. Nor do they produce heat. The term "cold laser" is often used when referring to these devices.
Both devices are thought to operate via the theory of photobiostimulation. This process has recently regained popularity as a possible treatment for wound healing. Documented in cell culture, cellular activity is altered by irradiation with light. Photobiostimulation may be mediated via the production of reactive oxygen species or heat shock proteins. The exact mechanism of cellular stimulation likely depends on the particular cell involved, but this remains to be determined. Several groups have demonstrated that the energy density of the light source used is critical to the outcome of the therapy. At some energy densities cells will be stimulated, while at higher levels, the opposite effect may be produced.
Evidence exists in animal studies indicating LLLT may play a role in treating wound infections including those of bacterial and fungal etiologies (Bayat et al. June, 2005). Several different light systems with different wavelengths have been explored for use in wound healing. It does not appear that coherence of light plays a role in the process described above; true lasers and noncoherent light emitting devices can both be used (Klebanov et al. Jan, 2006).