Bilateral Axilla Hair Removal Comparing a Single Wavelength Alexandrite Laser With Combined Multiplexed Alexandrite and Nd:YAG Laser Treatment From a Single Laser Platform
February 2012 | Volume 11 | Issue 2 | Original Article | 185 | Copyright © February 2012
This study compares the efficacy, safety, and side-effect profile of three different firing modes in a single laser emitting both dual-wavelength multiplexed laser pulses and single-wavelength pulses for removing unwanted axillary hair in subjects with Fitzpatrick skin types II-V.
Subjects received four laser treatments at 4-6 week intervals. One axilla was treated with the alexandrite laser alone while the contralateral axilla was treated with multiplexed pulses delivering either a 755 nm/1064 nm pulse or a 1064 nm/755 nm pulse. Efficacy was evaluated through blinded hair counts performed on digital photographs taken two and six months following the final treatment.
Mean hair clearance percentages were 83%, 81%, and 86% for the alexandrite, alexandrite/YAG sequence, and YAG/alexandrite sequence, respectively. Side effects were minimal and did not differ by treatment.
Muliplexed 755 nm/1064 nm and 1,064 nm/755 nm pulses compared favorably with the 755 nm pulses for efficacy and side-effect profile, all being highly efficacious. Further study of the multiplexed pulses in various clinical settings, including refractory hair removal, are indicated.
J Drugs Dermatol. 2012;11(2):185-190.
Laser hair removal exploits the selective absorption of light by melanin pigment in darkly-pigmented hair shafts, resulting in heating of the hair shaft and transfer of the heat energy to the follicular unit. Heating of the hair follicle and resulting damage to the surrounding cells results in inflammation
that triggers hair follicles to enter a prolonged telogen phase, with shedding of the terminal hair which is replaced by a vellous hair which is not visible to the naked eye. The lasers that are currently most frequently used for laser hair removal are in the visible-red to infrared wavelength range and include: the 755 nm alexandrite laser, the 810 nm diode laser, and the 1,064 nm neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers.1-28 Although melanin absorption decreases with increasing wavelength
from the ultraviolet into the infrared, lasers emitting in the red and infrared wavelengths are used for laser hair removal because they penetrate deeply into the skin when administered with a sufficiently large spot size, and avoid competing chromophores
such as hemoglobin and water.1-28 Patients with lighter skin types and darker hair are ideal candidates for laser hair removal,
since the contrast between epidermal pigment and hair pigment are the greatest in these individuals.
Although any of the three wavelengths used for laser hair removal should work well in lighter-skinned patients, the shorter 755 nm alexandrite and 810 nm diode wavelengths should yield the best results in these patients due to their ability to be absorbed more strongly by melanin pigment in the hair due to a relative lack of epidermal
melanin. In addition, lasers using these two wavelengths run less of a risk of unwanted side effects in lighter-skinned patients
and may better target less darkly pigmented hair in these patients. Although the ruby laser was the first laser applied to laser hair removal, technical difficulties in producing reliable hair removal
lasers at the 694 nm wavelength and the risk of damage to the epidermis from this relatively short wavelength, have rendered it obsolete. Darker-skinned patients have a greater risk of damage to epidermal melanin-containing cells when treated with shorter wavelength lasers, and are generally more safely treated with the 1,064 nm, Nd:YAG laser. Although epidermal melanin and melanin in the hair shaft both absorb light, there exists with the Nd:YAG laser the possibility of having one's cake and eating it too in skin of color. Relative sparring of the epidermis can be achieved when using 1,064 nm, while this wavelength is still capable of targeting the much denser pigment in the hair shaft, and is ideal for treat-