In a clinical study by Weiss et al. (2005b) 10 patients were treated with LLLT (590 nm, 0.10 J/cm2), for acute sunburn, once or twice a day for 3 days, where only half of the affected area was treated. A reduction in redness, swelling, burning and peeling was reported by the patients post-treatment. In one of the individuals who received treatment twice a day for 3 days, immunofluorescence staining showed that the LLLT treated area exhibited a reduction in MMP-1. Furthermore, the light treated area also exhibited a decrease in MMP-1 gene activity, both 4 and 24 hours post-UV injury, as shown by reverse transcription-polymerase chain reaction (RT-PCR). Four days after UV exposure, changes in inflammation and the dermal matrix were also reported to be associated with LLLT treatment (Weiss et al., 2005b).
Burn scars are problematic to treat as they progressively worsen with hypertrophy and contracture, thus, with limited treatment options, LLLT may be a potential mode of treatment. In a study consisting of 19 patients with burn scars, the patients were treated with a low-powered light source (400 mW, 670 nm, 4 J/cm2), twice a week over a period of 8 weeks. Post-treatment, the scars were reported to be softer and more pliable. Additionally, relief from pain and pruritus, and, occasional improvements in scar patterns (within mesh grafts) were also reported. These effects were sometimes limited, and thus, complete scar disappearances could not be expected. Moreover, it is important to note that, following treatment, better results were obtained in the cases where the burn scars were not more than 12 months of age (Gaida et al., 2004).