Hair Removal by Long-Pulse Alexandrite Laser in Oriental Patients

Abstract

The laser depilation system, cleared by the Food and Drug Administration since 1995, is evolving rapidly. However, the parameters in the hair removal function of these devices emphasize use for white people with fair skin (Fitzpatrick types I, II, or III). The characteristics of oriental skin and hair are black, coarse hairs in darker skin (Fitzpatrick types IV or V). As seen, the higher the skin melanin content, the more difficult to remove hair by laser. The authors report 146 oriental patients (156 body sites) who underwent treatment with the long-pulse alexandrite laser (wavelength, 755 nm) depilation system since November 1997. Percentage of hair removal (clearance rate) was assessed, and the histological change from laser pulse damage was observed. After two treatments, the clearance rates in the axillae and the leg were 61% and 62% respectively in the 15 to 20-J group (N = 47), and were 66% and 67% respectively in 21 to 25-J group (N = 64). After five treatments, 59 patients (37 axillae and 22 legs, all of which received 21-25 J per square centimeter of laser energy treatment during the course) had an average clearance rate of 91% (axillae) and 86% (leg), and the clearance rates have been maintained near 90% after long-term follow-up (average follow-up, 17 months). Minimal and transient complications are noted. In conclusion, using a combination of longer wavelength (but still in the optimal window of 630-870 nm), long pulse duration (10-40 msec), high fluence (but limited up to 25 J per square centimeter), multiple treatments, and concomitant direct cooling applied to the skin of oriental patients (Fitzpatrick types IV and V) with black, moderately coarse hair shafts achieves satisfying long-term hair removal results.

Hair induction after laser-assisted hair removal and its treatment

“…They target melanin in the hair follicles with pulse durations in the millisecond range. [1][2][3][4][5] According to the theory of selective photothermolysis, the light energy is absorbed by melanin in the hair shaft and is transformed into thermal energy, causing damage to the hair follicle structure. The short pulses (usually shorter than the thermal relaxation time of the follicle) limit the thermal damage to the follicles and, therefore, surrounding tissue is spared.…”

A Randomized, Controlled, Double-Blind Study Evaluating Melanin-Encapsulated Liposomes as a Chromophore for Laser Hair Removal of Blond, White, and Gray Hair

“…10 The technique of laser-assisted hair removal has been described with the ruby laser (694 nm), alexandrite laser (755 nm), diode laser (800 nm), and neodymium:yttrium aluminum garnet (Nd:YAG) laser (1064 nm) for long-term hair reduction. [11][12][13][14] The mentioned lasers target melanin to achieve selective photothermolysis of the hair follicles. The same mechanism of action is used by intense pulsed light sources (IPL) that consist of a noncoherent filtered flash lamp that emits wavelengths ranging from 500 to 1200 nm.…”

Agent-based model of laser hair removal: A treatment optimization and patient education tool

“…[16] The hair damage is also proportional to the thickness of hair. [17] The thickness and pigmentation of the hair were graded as 1 and 2. The proportionality constants A and B were roughly approximated to 4 × 10 -4 and 3 × 10 -4 , respectively based on available clinical data.…”