Poor penetration of infra-red and helium neon low power laser light into the dermal tissue.

The skin transmittance for low power laser light was studied in vitro. The penetration of both He-Ne and infra-red lasers was observed for only a few millimeters. The most important absorption was observed at the depth level of 0.4 and 0.5 mm. These results suggested that the dermal vascular plexus barrier seemed to decrease the penetration at that level. This finding should mean that the laser therapy did not have really direct effects on the deep tissues. However, the effects can be mediated by many different pathways.