WAVELENGTHS FOR PORT-WINE STAIN LASER TREATMENT - INFLUENCE OF VESSELRADIUS AND SKIN ANATOMY

Recent Monte Carlo computations in realistic port wine stain (PWS) mod els containing numerous uniformly distributed vessels suggest equal de pth of vascular injury at wavelengths of 577 and 585 nm. This finding contradicts clinical experience and previous theory. From a skin model containing normal and PWS vessels in separate dermal layers, we estim ate analytically the average volumetric heat production in the deepest targeted PWS vessel. The fluence rate distribution is approximated by Beer's law, which depends upon the tissue's effective attenuation coe fficient, and includes a homogeneous fractional volumetric blood conce ntration corrected for finite-size blood vessels. The model predicts 5 85-587 nm wavelengths are optimal in adult PWSs containing at least on e layer of small-radius blood vessels. In superficial PWSs, typically in young children with small-radius vessels, 577-580 nm wavelengths ar e optimal. Wavelength-independent results similar to those from Monte Carlo models are valid in single-layered PWSs of large-radius vessels. In conclusion, the volumetric heat production in the deepest targeted PWS blood vessel can be maximized on an individual patient basis. How ever, absorption of 585-587 nn wavelengths is sufficiently high in sup erficial lesions, so we hypothesize that these wavelengths may be cons idered adequate for the treatment of any PWS.