COMPARATIVE EFFECTS OF EXPOSURE TO DIFFERENT LIGHT-SOURCES (HE-NE-LASER, INGAAL DIODE-LASER, A SPECIFIC TYPE OF NONCOHERENT LED) ON SKIN BLOOD-FLOW OF THE HEAD

Background and Objective: This study assessed the effects of optic sti muli emitted by three different light sources on head skin blood flow. Materials and Methods: The irradiation effects of the He-Ne laser (63 2.8 nm, 10 mW, total energy appr. 9.4 J), the InGaAl diode laser (670 nm, 60 mW, appr. 108 J) and monochromatic light (635 nm, 112.5 mW, app r. 202.5 J) were measured using laser Doppler technology. The correspo nding fluences (energy densities) varied from 0.01 J/cm(2) (He-Ne) to a range of 0.12 - 0.72 J/cm(2) (InGaAl) and 0.22 - 1.36 J/cm(2) (LED). The investigation was completed under single-blind, placebo-controlle d conditions where the subjects (10 male healthy volunteers) were expo sed on two occasions to the placebo (LED)-device against the laser (He -Ne or InGaAl). Results: A short lasting vasodilation, a 54 per cent i ncrease (p<0.05) in skin blood flow was seen after the InGaAl irradiat ion (fluences between 0.12 - 0.36 J/cm(2)) whereas the non-coherent mo nochromatic irradiation (0.68 - 1.36 J/cm(2)) used in this particular study decreased blood flow by 36 per cent (p<0.05). The He-Ne irradiat ion (0.01 J/cm(2)) had no effect. Skin temperature changes were insign ificant. Conclusions: Skin blood flow changes seemed to be related mor e on radiant exposures than coherency.