Effect of low-power density laser radiation on healing of open skin wounds in rats
J. S. Kana, G. Hutschenreiter, D. Haina and W. Waidelich
We performed a study to determine whether laser radiation of low-power
density would affect the healing of open skin wounds in rats. The wounds
were irradiated daily with a helium-neon laser (wavelength, 632.8 nm) and
an argon laser (wave-length, 514.5 nm) at a constant power density of 45
mW/sq cm. The rate of wound closure was followed by photographing the
wounds in a standardized way. The collagen hydroxyproline concentration in
the scar tissue was determined on the 18th postoperative day. Helium-neon
laser radiation had a statistically significant stimulating effect on
collagen synthesis in the wound, with a maximum effect at an energy density
of 4 joules/sq cm. The rate of wound closure was enhanced significantly
between the third and 12th postoperative days. The argon laser exposure
produced a significant increase in collagen concentration both in
irradiated and nonirradiated contralateral wounds. However, an acceleration
of the healing rate was not registered in this case. The wound contraction
up to the fourth day of the experiment was inhibited under helium-neon and
argon laser exposure to 20 joules/sq cm. The described effects were not
specific for the laser light. There may be a wavelength-selective influence
of coherent light on the metabolic and proliferation processes in wound
healing, with the associated problem of the possible carcinogenic effects
of laser radiation.
