Ablation and Thermal Depths in VSP Er:YAG Laser Skin Resurfacing

The list of indications for which Variable Square Pulse (VSP) Er:YAG laser systems can be used is continuously expanding. For example, ablative fractional resurfacing treatments performed with the VSP Er:YAG laser have good clinical outcomes and significantly shorter recovery times and adverse effects compared with traditional ablative laser skin resurfacing. Recently, an Er:YAG laser operating in variable pulse length, non-ablative, SMOOTH mode, for use in new collagen synthesis, has been introduced. The broad range of available Er:YAG modes of operation call for a more systematic understanding of the thermal and ablative effects this laser has on skin tissue. In this study, a theoretical micro-explosions computer (MEC) model is developed that explicitly links laser and tissue parameters with the clinical end effects of ablation and residual heat deposition. The computed results are then compared with experimental measurements of ablation rates and heat deposition in skin. The MEC model is found to be in good agreement with experiment, and has already been implemented in the latest VSP Er:YAG laser systems as a software tool for automatic calculation of the expected ablation and thermal depths in clinical procedures.