In 2010, approximately 30% of all cosmetic procedures were performed on non-Caucasian ethnicities in the United States.1 With almost a million laser hair procedures performed annually, the need for safe and effective treatments is paramount.
Laser hair removal is based on the principal of selective photothermolysis with the goal of selectively heating a target chromophore, in this case follicular melanin, with minimal damage to surrounding tissue.2 In darker-skinned individuals (Fitzpatrick skin types IV-VI), there is an increased risk of damaging epidermal melanin with lasers and light sources, as much of the energy can be absorbed by the heavily pigmented basal layer. Depth of transmission of light energy increases steadily as the wavelength is increased from 400 to 1,200 nm.3 Melanin absorption is also lower in longer visible and infrared wavelengths. By using a laser or light source with a longer wavelength, deeper penetration, and with less melanin absorption, such as 1,064-nm light, less energy is absorbed by epidermal melanin and can be preferentially delivered to deeper dermal structures like the hair follicle. The use of devices with epidermal cooling also helps to limit unwanted epidermal damage.
In our practice, we typically use a 1,064-nm, flash lampâ€“excited, long-pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (GentleYAG; Candela, Wayland, MA) for laser hair removal in more darkly pigmented patients (Fitzpatrick skin types IV-VI). We generally start with a pulse duration of 3 milliseconds (ms), a 12-mm spot size, and fluences of 24 to 32 J/cm2, depending on skin type. Fluences may be increased with subsequent treatments, depending on patient response. The device comes equipped with a dynamic cryogen spray-cooling device, which we typically set on 50 ms of cryogen spray, followed by a 20-ms delay before the laser is fired. Hair reduction is often noticeable even after one treatment but becomes more significant after a series of treatments. The number of treatment sessions is determined in part by the body site and the density
of hair. Arms and legs are particularly responsive, requiring 3 to 6 treatments; the axilla and bikini areas are more resistant, and the lip and chin can be stubborn areas to treat. A patient with a typical response after 3 treatments is shown in Figure 1. There