ABSTRACT
References 241
Based on the original work by Anderson and Parrish (1,2), pulsed lasers have become the
mainstay of treatment for an ever-expanding number of cutaneous conditions. The rapid
proliferation in the number and types of lasers used to selectively heat target tissues is
even more remarkable when considering that this evolution occurred during less than
two decades. Anderson and Parrish used a predictive model to choose a laser that would
selectively target blood vessels. They modeled the wavelength, duration of exposure,
and energy density necessary to destroy blood vessels. Initially, they chose a wavelength
of 577 nm due to the strong hemoglobin absorption at this wavelength. They estimated that
the optimal pulse duration for targeting unwanted cutaneous vessels was approximately
1 ms, based on experimental estimates of thermal relaxation for microvessels in Caucasian
skin (1-3). The laser they selected had a pulse duration of 0.3 ms, less than the 1 ms pulse
duration that they estimated to be optimal for targeting of cutaneous vessels, but at
the limits of what was technically achievable at the time (1). Previously, continuous
nonpulsed vascular lasers had an unacceptable side effect profile, resulting in necrosis
of skin overlying blood vessels (1-3). This necrosis often resulted in permanent scarring.
