Helium‐neon laser irradiation at fluences of 1, 2, and 4 J/cm2 failed to accelerate wound healing as assessed by both wound contracture rate and tensile strength

Abstract

Background and Objective Reports in the literature indicate that low energy laser irradiation has a biostimulatory effect on wound healing; however, no mechanism of this effect has been elucidated. Study Design/Materials and Methods: We attempted to establish a model from which to study the mechanism of biostimulation. The effects of low energy helium-neon irradiation on wound healing were observed in two rat models. In the first model, 1.5 cm diameter full thickness excisional skin defects were created in the dorsal midline of rats (n = 32). All animals were anesthetized and all eschars were debrided daily. Wound area was determined by caliper measurements for 2 weeks postoperatively. Rats that received a treatment of 1 J/cm2 had two defects in the dorsal skin. One wound was treated and the second was used as its own control. These measurements were not blinded. Rats that received 2 J/cm2, 4 J/cm2, or anesthesia alone had one defect on the dorsal skin. Caliper measurements of these wounds were blinded. We were unable to demonstrate any difference in the rate of wound contracture in rats that received a daily dose of 1 J/cm2, 2 J/cm2, 4 J/cm2, or anesthesia alone (P > 0.8 by student's t-test). In the second model, a single 2 cm longitudinal full thickness skin incision was created in the dorsal midline of each rat (n = 24). No difference was found between rats that received anesthesia alone and those treated daily with 2 J/cm2 as assessed by tensile strength measurements on postoperative days 7 and 14 (P > 0.8 by student's t-test between groups at both time points). These determinations were blinded. Results Despite our intentions of studying the mechanism of low energy HeNe biostimulation, we were unable to demonstrate a beneficial effect. Conclusion In this study, helium-neon laser irradiation produced no measurable benefit on wound healing. Lasers Surg. Medicine 20:340–345, 1997. © 1997 Wiley-Liss, Inc.