Port-wine stains are congenital malformations of the superficial dermal vasculature characterized by ectatic capillary vessels. The pulsed dye laser (PDL) is now routinely used for treating such vascular malformations. The PDL induces selective damage to cutaneous blood vessels and has a wavelength of 585 nm, which causes a 0.5- to 1.2-mm deep injury in the skin. It has a pulse duration of 450 microseconds, which is shorter than the thermal relaxation of cutaneous blood vessels. This restricts thermal damage to the blood vessels and spares the surrounding skin, thereby minimizing scarring.
Shahidullah H, Frieden IJ. Eczema as a Complication of Pulsed Dye Laser Therapy. Arch Dermatol. 1999;135(2):215-216. doi:10-1001/pubs.Arch Dermatol.-ISSN-0003-987x-135-2-dlt0299