ABSTRACT
BACKGROUND Vascular lesions are the most common indication for laser therapy today. While the ruby laser, the neodymium: yttrium-aluminum-garnet (Nd:YAG) laser, the argon laser, and the carbon dioxide laser were developed in the early 1960s, the widespread use of lasers for vascular lesions began in the 1980s with the application of the theory of selective photothermolysis. Selective photothermolysis, described by Anderson and Parrish, is the ability to target and damage a specific chromophore, such as oxyhemoglobin, with minimal damage to the surrounding tissue. By setting the laser pulse duration to a time equal to or shorter than the thermal relaxation time of the target vessel (time for the target vessel to dissipate half of the thermal energy or heat), thermal damage to the surrounding normal tissue is avoided. Oxyhemoglobin is the major chromophore in the cutaneous blood vessels of port-wine stains, hemangiomas, and telengiectases. The major absorption peaks of oxyhemoglobin are 418, 542, and 577 nm. The higher wavelengths are less absorbed by epidermal melanin and allow deeper penetration.
