Laser-photothermal effect on skin tissue – Damage and recovery

Abstract

The impact of laser photothermal interactions on tissue damage and recovery was studied. A Ho:YAG laser (2.12 μm) was used to irradiate rabbit skin with different operating parameters. The thermal effect on the skin tissue was examined by measurement of laser-induced lesions and by tissue histology. The lesion size on the surface, the photocoagulation depth and the thermal damage depth were recorded as functions of irradiation parameters. The lesion width and the photocoagulation depth increased with the beam energy while the area of thermal damage remained relatively unchanged. At the fluence levels of 453 J/cm $^{2}$ and 680 J/cm $^{2}$ , laser energy damaged the dermis all the way to the panniculus carnosa, resulting in total dermal collagen photocoagulation, but with little damage to the muscle. Post-treatment histological observation showed a rapid tissue healing and skin regeneration process. The thermal damage on rabbit skin began recovery within a short period and new epithelial growth was clearly seen at day 3. By 7 days, most of the photocoagulated zone was separated from the main body and was replaced by a new layer of epithelium.