The effect of polarized light on wound healing

Abstract

Recent investigations have reported contradictory results on the influence of low-power lasers and polarized light on wound healing. Different biologic effects have been observed after light irradiation but the real benefits of phototherapy in the healing of wounds in patients are still controversial. This article reports on a randomized, prospective single blind study that was set up to evaluate the effect of polarized light (wave length 400–2000 nm, degree of polarization >95%, power density 40 mW/cm2, light energy 2.4 J/cm2) on the healing of standardized wounds. Twenty pairs of identical donor areas of split thickness skin grafts, taken on a similar location on each of the 20 patients, were treated according to an identical wound care protocol. The only difference was that one side was treated with polarized light and the other side without. The healing of these paired wounds was evaluated in a standardized manner and on a daily basis by two independent and blinded observers. The parameters assessed were: the degree of epithelialization, the quality of the granulation tissue, the degree of inflammation, the degree of infection, the aspect of the early scar tissue, blister formation, and the subjective feeling of the patient. Every parameter was scored on a 1–5 scale, with score 1 for the worst and score 5 for the best outcome. Long-term follow-up was performed after 1 month, 3 months, 6 months and 1 year. For all variables, except for infection and blister formation which was not seen in either group, highly significantly better scores were obtained in the donor sites treated with polarized light. Inter-observer agreement was acceptable to very good in all outcome variables. The results of this study demonstrated that polarized light had a beneficial effect on the healing of these standardized wounds, resulting in a faster epithelialization and an improved quality of early scar tissue formation.