Table of Content

Archive

Summer 2015, Vol. 23 No. 2

Hong Kong J. Dermatol. Venereol. (2015) 23, 69-70


Views and Practice

Pearls for performing laser hair removal

Y Chan 陳湧

Removal of unwanted hair by laser is a very popular treatment nowadays. With the application of extended theory of selective photothermolysis, unwanted hair can be precisely removed without damaging the surrounding tissues. As the melanin in the hair shaft acts as the chromophore, the heat from laser diffuses to follicular stem cells in the bulge region or dermal papilla to achieve permanent hair removal. However, this procedure is not without risks and the importance of careful patient selection and using appropriate parameters cannot be underestimated.

Medical history suggesting photosensitivity, connective tissue disease or pregnancy should be reviewed and carefully discussed with the patient. History of hair removal attempts and their results should also be reviewed. Before the procedure, always remind the clients not to remove the hair by its roots, like waxing or plucking for at least six weeks before the procedure. If the hair length is still causing trouble, shaving should be advised which only removes the hair above the skin. Patients can gently shave the hair over treatment areas the day before by themselves to save the preparatory time in the clinic or it can also be done right before the laser treatment.1

Topical anaesthetic cream is rarely required but may still be considered for treating beard or bikini areas as it can result in more pain especially if the cooling system of the laser device is less efficient.

Laser hair removal works best in patients with fair skin and dark terminal hair. As the epidermal melanin in patients with darker skin acts as the competing chromophore to melanin in hair shaft, the safety margin is lowered when the skin is tanned. The patient should avoid excessive sun exposure for at least one week before and after the treatment. The treatment should be deferred if the patient has tanned recently as this considerably increases the risk of skin burn.

For the laser device, one with high frequency, large spot size, variable pulse duration and efficient cooling system can effectively shorten the duration of treatment and risk of burning. Table 1 shows some of the available machines for hair removal. I am using GentleLase Pro at my clinic with dynamic cooling device. The energy should be tailored to the skin and the hair colour. During the procedure, monitoring of the patient's pain tolerance should be advocated as unusual pain may suggest skin burn.

Table 1 Commonly used machines for hair removal
System (make) Laser type Wavelength Pulse duration Spot size Maximum frequency (Hz) Cooling system
Apogee+®(Cynosure) Long pulsed alexandrite 755 nm 0.5-300 ms 5-18 mm 3 Cold air
Clarity (Lutronic) Long pulsed alexandrite & Nd:YAG 755/1064 nm 0.35-300 ms 2-20 mm 10 Cryogen
Emax DS (Syneron Candela) Intense pulsed light 680-980 nm + RF Max 100 ms 25x12 mm 0.7 Contact
Excel HRTM (Cutera) Long pulsed alexandrite & Nd:YAG 755/1064 nm 0.1-300 ms 3-18 mm 2 Contact
GentleLase Pro®(Syneron Candela) Long pulsed 755 nm 3-300 ms 6-18 mm 2 Cryogen
Lightsheer® (Lumenis) Long pulsed diode 805 nm 5-400 ms 9x9 mm 2 Contact
Note: RF=Radiofrequency

There are a few home-used light-based hair removal devices that bring the procedure back home without the need of attending clinic. Some of these devices have gained FDA clearance and are gaining popularity on the market. However, the evidence for their efficacy is scanty and the potential risks of light-based device in untrained customer hands cannot be overlooked.2,3

Patients should always apply sunscreen and moisturisers after hair removal treatment. Not uncommonly, patients may have perifollicular erythema and swelling over the treated area which may last for a few days after the procedure; cold compression, topical steroid and moisturisers help to relieve the oedema. Efficacy of hair removal varies with different skin types, different light devices and pararmeters used, therefore patients should be reminded that only around 15% of hair is removed in one session of treatment.2 Thus, repeated treatment sessions in every four to six weeks are needed to achieve a desirable result.4

Just as other skin procedures, before and after clinical photos should be advised and informed consent covering risks of pigmentary changes, paradoxical hypertrichosis, burns, blisters or even scar formation must be obtained prior to the procedure.

References

1. Buddhadev RM; IADVL Dermatosurgery Task Force. Standard guidelines of care: laser and IPL hair reduction. Indian J Dermatol Venereol Leprol 2008;74 Suppl:S68-74.

2. Hruza G, Avram M. Lasers and Lights: Procedures in Cosmetic Dermatology Series. 3rd edition. Saunders, 2012.

3. Town G, Ash C, Dierickx C, Fritz K, Bjerring P, Haedersdal M. Guidelines on the safety of light-based home-use removal devices from European Society for Laser Dermatology. J Eur Acad Dermatol Venererol 2012;26:799-811.

4. Casey AS, Goldberg D. Guidelines for laser hair removal. J Cosmet Laser Ther 2008;10:24-33.