Laser Treatment in Hirsutism: An Update

Unwanted hair growth, which is a common aesthetic problem, has traditionally been treated using various techniques such as shaving, waxing, and epilation, but most of these provide only a temporary solution. Laser and light-based technology for hair removal has become one of the fastest growing procedures in modern cosmetic dermatology in the last decade. Clinical experience suggests that in the ideal subject with fair skin and dark hair, laser treatment can reduce hair growth significantly. This article reviews the various laser and light-based devices used for hair removal along with the various laser and patient parameters that affect the outcome of laser treatment for hair removal. Photoepilation, when properly used, offers clear advantages when compared with older, traditional techniques.

should not be compromised during laser hair removal as this can decrease response to treatment. The following sections explain these factors in detail.

Skin Type
Light skin (Fitzpatrick skin type I-IV) and dark hair are an ideal combination for effective hair removal. Since the chances of epidermal melanin absorption are less with higher fluence, short pulse duration can be used [9,10]. The absorption is more at the level of follicular melanin rather than epidermal melanin, thus reducing the chances of epidermal damage. The long-pulsed Nd:YAG laser remains the recommended choice in very dark individuals and tanned patients because of its longer wavelength [11]. The safety of patients with type V-VI skin is a challenge for laser hair removal because of the high density of competing chromophore in the epidermis. A wavelength that is less absorbed by melanin may be less effective clinically as the target chromophore for hair removal laser is melanin in the hair bulb and bulge.

Type of Hair, Color of Hair, and Stage of Hair Cycle
The anagen hair is more prone to laser therapy since melanin is present only in anagen hair. At any given time, almost 10%-15% of hair may be catagen or telogen stage; hence treat ment has to be extended for many months to cover as many hair follicles in its anagen stage.
Terminal hair, being more pigmented, responds better than vellus hair. Good response to laser hair removal occurs when the targeted hair has a high concentration of chromophores. Thin, fine hairs have less pigment and hence are poor choices for laser hair removal, even with best fluences and multiple treatments, compared with thick terminal hairs [12,13]. This is true when treating areas such as the upper lip, where chromophore in vellus hairs is less for laser wavelength absorption.  [3].   A summary of commercially available lasers is given below.

Normal-Mode Ruby Laser (694 nm)
The pulsed ruby laser was originally

Site of Hair Removal
Since there are differences in anagen-telogen ratios in various anatomic sites, there may be differences in response rates. Axillae and belt areas respond better than legs, arms, and chest. The procedure for laser hair removal is summarized in Figure 1.

Grading of Efficacy
Efficacy is graded according to a 4-point visual scale ranging from poor to excellent depending on the percentage of hair reduction from baseline: poor: <25%;

Hormonal Profile
Patients should be evaluated for hirsutism by doing various hormonal assays, especially for testosterone levels, as these may influence the response to laser therapy. Polycystic ovarian syndrome, thyroid dysfunctions, adrenal hyperplasias, and hyperprolactinemia are hormonal dysfunctions that influence hair regrowth following laser hair removal [14,15].  ranged from 40% to 80% at 6 months after several treatments [19].

Diode Laser (800-1,000 nm)
Diode lasers for hair removal were cleared to market in the USA in 1997.
Individuals with darker skin can be treated more safely with this system because of the longer wavelength, the active cooling, and the longer pulse widths. The diode laser system has been found to be better tolerated by patients with darker skin types (V-VI) than the ruby laser. Variable success rates rang-

New Combination
Trio is a single multiplex diode laser hand piece that offers the synergistic benefits of the 3 most effective wavelengths for hair removal.

ALEX 755 nm Wavelength
The superficial penetration of 755 nm wavelength targets the bulge of the hair follicle and has thus been found to be more effective for superficially embedded hair in areas such as the eyebrows and upper lip.

SPEED 810 nm Wavelength
It is especially helpful because of its deep penetration capabilities that target the bulge and bulb of the hair follicle. It is also ideal for treating the arms, legs, beard, and cheeks by moderate tissue depth penetration.

YAG 1,064 nm Wavelength
As this wavelength offers the deepest penetration of hair follicle, it targets the bulb and the papilla and also treats the deeply embedded hair in areas like the scalp, axillae, and pubic areas.

Vacuum-Assisted Laser Hair Removal
In vacuum-assisted laser hair removal, a vacuum gently draws the skin into the hand piece; skin is stretched thin and thereby the target is pulled closer to the energy source. Energy when applied to the target leads to spreading apart of the melanocytes and constriction of blood flow. Target is damaged and skin is released [37].

Large Spot Size
Vectus (Palomar) is a hair removal system that uses a diode laser. It has a large spot size, which makes large areas such as back of legs easier to treat.
The large spot size provides efficacious hair removal due to photon recycling and increased depth of penetration. In a study, 18-mm spot size was more effective than 12-mm spot size [37].

Super Hair Removal
The original concept of progressive photothermolysis is included in the operation of the diode laser super hair removal (SHR) for photoepilation.
During treatment, pulse repetition of the laser system SHR is 10 Hz. Depilation is performed through the continuous movement of the hand piece over the skin surface while delivering laser pulses, which prevents energy from concentrating on a particular point and thus generating burns due to overheating.
Due to the relatively long-duration pulse of the laser SHR and its high repetition frequency, the laser energy penetration is secondarily increased and reaches deeper into the skin through a thermal propagation mechanism [38].

Comparison of Different Laser and Light-Based Devices
The majority of studies have documented a superior efficacy of alexandrite and diode laser systems in hair removal in comparison with other lasers or light-based devices. In a study that compared the efficacy of 3 laser devices, a mean hair reduction of 59.5%, 70.3%, and 47.4% was reported after 3 sessions with diode, alexandrite, and Nd:YAG lasers, respectively [29,30]. In a randomized, split-face study, a mean reduction in hair count of 46% and 27% was reported after alexandrite and intense pulsed light systems, respectively [31].
In a comparative study on longpulsed Nd:YAG laser and intense pulsed light system in skin types IV-VI, the former device was found to be more effective than the latter for hair removal, with fewer side effects. In darker skin types, a superior efficacy of Nd:YAG laser over intense pulsed light system has been demonstrated [14].

For Light, White, and Gray Hair
Laser hair removal is based on target-