Laser Hair Removal

Based on the principle of selective photothermolysis first described by Anderson and Par­rish [63], several laser and light-based systems have been developed to affect hair growth. Under this principle, advantage is taken of the high concentration melanin pigment at the base of the anagen hair follicle and its absence in the surrounding dermal tissue that can selectively absorb and convert to heat select wavelengths of laser and light energy. Based on the hair-follicle pigment concentration and the laser parameters used, the amount of thermal energy released can cause mild to severe damage to the follicle, resulting in a range of hair reduction from being a temporary to a permanent effect [64-67]. In general, the efficacy of a laser or light-based treatment is proportional to the melanin concentration in the hair fol­licle and the amount of laser energy used. A darker hair generally responds well, whereas the treatment is less effective or even ineffective on gray, blonde, red or light-brown hair. The presence of melanin in the skin epidermal layer is the determining factor as to how much laser energy (fluence) can be safely used without inducing dermal damage. The face remains one of the key areas for which women seek laser treatment. Because hair growth on the face tends to be less uniform than other body areas, and pigmentation and growth rate can vary significantly depending on the facial site (upper lip, chin, cheek or neck), it presents certain challenges for achieving a consumer satisfactory effect with the laser treatment alone. Laser hair removal, particularly for the face, is described in detail in other chapters in this book (see Goldberg, chapter 5; Styczynski, chapter 6 and Sadick, chapter 7).