A new optimal wavelength for treatment of port wine stains?

In this study we investigate light penetration into skin in order to define the optimal wavelength for the treatment of port wine stains. A two-layer model (epidermis and dermis) is applied with a cylindric tube representing the ectatic blood vessel. Light propagation is calculated by the Monte Carlo method. Values for the optical properties of the skin were not only taken from the literature, but also derived from measurements of the spatially resolved reflectance on the human forearm applying a multilayer model. Using the new values, the maximal depth of selective vascular injury better fits experimental and clinical observations, compared to the values in literature. In addition, the optimal wavelength for treatment of port wine stains is shifted to longer wavelengths.