Diode lasers emit monochromatic laser light at a wavelength of 800 nm or 810nm [19-21]. Dierickx evaluated the effectiveness and safety of an 810 nm pulsed diode laser for the permanent reduction of unwanted hair. He studied 95 subjects composed mainly of Fitzpatrick II-III skin phenotypes and those with brown or black hair. Subjects were treated and examined at baseline, 1, 3, 6, 9, and 12 months after treatment. The authors evaluated one versus two treatments, single versus multiple-pulse treatments of the same area, and the fluence-response relationship. Pulse durations from 5-20 msec and fluences between 15-40 J/cm2 were utilized in this study.
Treatment results demonstrated two different effects on hair growth: hair growth delay and permanent hair reduction. A measurable growth delay was seen in all patients (100%) at all fluence/pulse width configurations tested; this growth delay was sustained for 1-3 months. Significant fluence-dependent, long-term hair reduction occurred at all fluences in 88% of subjects. Clinically obvious long-term hair reduction usually required >30 J/cm2. After two treatments at 40 J/cm2 , with a 20 msec pulse duration, the average permanent hair reduction at the end of the study (12 months after final treatment) was 46%. Two treatments significantly increased hair reduction as compared to one treatment, with an apparently additive effect. At a fluence of 40 J/cm2, the initial treatment removed approximately 30% of terminal hairs, and the second treatment given one month later removed an additional 25%. Triple pulsing of the same area did not significantly increase hair reduction over single pulsing, but did increase the side effects. Additional findings included reduction in hair diameter and reduction in color of regrowing hairs (lighter hair).
In another study, Campos et al. treated 38 subjects with 1-4 treatments using an 800 nm diode laser [22]. They utilized fluences of 10-40 J/cm2 and evaluated results four months after a final treatment. They noted that 59% of subjects had only sparse growth at the end of the study. Better results were seen after multiple sessions and with the use of higher flu – ences. However, this study was limited by its short final follow-up duration.
In a longer 20-month study, Lou et al. treated 50 Fitzpatrick skin types II-III subjects using an 800 nm diode laser with fluences of 10-40 J/cm2 and pulse durations varying between 5-30 msec [23]. They noted increasing improvement with increasing numbers of sessions. Hair regrowth plateaued at six months with hair regrowth varying between 47% and 66% at the end of the study.
Other groups have also studied the diode laser for hair removal. Bouzari et al. studied the affect of treatment interval on hair reduction with an 800 nm diode laser [24]. All patients studied, received either two or three treatments. Patients treated at 45-day intervals had a 78.1% mean hair reduction, while those treated at 90-day intervals had only a 28.7% reduction. They concluded that shorter intervals were more successful at eliminating hair. Fisker – strand et al. compared the efficacy between two different long-pulsed diode lasers in a split-face study [25]. They found the MedioStar® and Lightsheer® systems to be equal in efficacy. A different group studied the effect of various spot sizes on hair removal efficacy with a long-pulsed diode laser and found that a larger spot size (14 mm) was superior to a smaller spot size (8 mm) [26]. Finally, Adrian et al. found the long-pulsed diode laser safe and effective at removing hair in African-American patients [27].