McDaniel et al. [31] reported long-term efficacy of alexandrite laser treatment on the upper lip, leg, back, and bikini area in 22 patients with Fitzpatrick skin types I—III. The hair removal efficacy varied with the site, pulse duration, and the number of treatments administered. A spot size of 10 mm, and a fluence of 20 J/cm2, was compared at pulse durations of 5, 10, and 20 msec. A single pulse of 10 msec duration at 20 J/cm2 was found to be most effective. Hair reduction at six months post single dose laser treatment was 40, 56, 50, and 15% for the upper lip, leg, back, and bikini area, respectively. The hair reduction on the upper lip increased from 40 to 54% when a second treatment was administered at 8 weeks after the initial treatment.
Women suffering from PCOS generally have an increased level of androgen hormone that results in terminal hair growth on the face, somewhat similar to the male beard, referred to as facial hirsutism. A randomized controlled trial was conducted in 88 PCOS patients using an alexandrite laser at a pulse width of 20 msec, and spot size of 12.5 mm [32]. The study was split into the high fluence (23.6 J/cm 2) treatment group and the low-fluence (4.8 J/cm2) sham control group. Each group received treatments for six months at 4-6 week intervals. The treatment group reported a significant reduction in the severity of facial hair, time spent on hair removal, as well as reduction in depression and anxiety. The sham control group showed minimal hair reduction benefit.
In another study [5], the quality of life measures were studied in 45 hirsute patients receiving laser hair removal treatments with long-pulsed ruby, diode, or long-pulsed alexandrite lasers. The patients completed dermatology life quality index (DLQI) questionnaires at various time intervals during the six-month study. A major improvement in DLQI scores was observed at one to two months after treatment, but longer-term benefit was not observed. There was a high level of patient satisfaction (71%) and willingness to undergo further treatments (78%), despite the fact that by 6 months after treatment, facial hair growth had returned to the pretreatment levels in almost all patients (97%). In this study, there was no evidence of permanent hair reduction on face.
A prospective study of 38 subjects (21 women, 17 men) was conducted by Campos et al. using an 800 nm diode laser [33]. Face (37%) and back (21%) were the two most common areas treated. The fluence level used was in the range of 20-40J/cm2 for skin types I-IV, and from 10-20 J/cm2 for the darker skin types V and VI. The mean number of laser treatments administered was 2.7 (range, 1-4). The clinical outcome data showed the face to be more responsive than the back; however the difference was not statistically significant. A long-term stable reduction in hair (permanent reduction) was seen in a majority of the patients at a mean fluence of 33.4 J/cm2 receiving a mean 2.8 treatments. Multiple treatments had an additive effect on efficacy.
The studies by Campos [33] and others [34-37] have shown the efficacy benefit of using higher fluence levels in achieving a stable long-term reduction (permanent) of hair. This can be more safely achieved in skin types I-IV, whereas in darker skin types (Fitzpatrick V/VI), there is a risk of causing serious dermal injury at the higher fluence levels. It is generally accepted that at a set fluence, the dermal adverse events are proportional to skin pigmentation, especially for skin types IV-VI. The risk of dermal injury can be reduced by providing adequate cooling to the epidermis during treatment, and by using longer wavelengths. Levy [34] treated 29 women with facial hirsutism representing all Fitzpatrick skin types using a long-pulse (4 msec) Nd:YAG (1064 nm) laser at fluence range of 56-70 J/cm2 and a spot size of 3 mm. Objective hair reduction at 3, 6, and 9 months after 3 monthly administered treatments was 43, 36, and 46%, respectively. This stable long-term reduction was similar to the results obtained by Sommer [38] who treated 43 patients with Fitzpatrick skin type I-IV for hirsutism using a near maximal tolerated dose of the ruby laser. The mean fluence exposure for this group was 48 J/cm2. Upper lip, chin, and neck were the three areas most often treated. There is a good literature agreement on greater dermal safety of Nd:YAG compared to other lower wavelength lasers for the darker skin types V/VI [34,39,40].