Laser hair removal as an approach for hypertrichosis
Information on hypertrichosis and hair removal treatments
Laser Hair Removal
Excessive hair disorders are a great embarrassment and a source of emotional stress to affected individuals. Cosmetic treatment, which improves the appearance, is essential to lessen the pains of these unfortunate people.
Laser hair removal systems are currently widely used for long-term hair removal. The need to have a fast and non-invasive treatment method led to the development of this treatment.
All laser treatment systems use the principle of selective photothermolysis where a selected chromophore is targeted by the laser to produce the heat that destroys the follicle. Therefore deep penetrating wavelengths in the range of 600 – 1100 nano meters (nm) are used. Care is taken to limit skin damage by restricting damage to the target area. This is done by ensuring enough laser absorption by the target and using a pulse rate shorter than the thermal relaxation time of the target.
The systems differ in the parameters like wavelength, pulse duration, fluence, spot size and repetition rate and in the cooling system used. The cooling device reduces heat conduction limiting skin damage and pain. The selection of these parameters is important for getting the ideal laser for an individual.
All laser treatment systems are more or less equally effective attaining on an average 20% long-term hair reduction with every treatment in 80% of cases. This shows that multiple treatments give better results. Likelihood of long-term hair reduction bears a strong correlation to hair color. Dark hair on fair skin responds better to treatment than blond, red or white hair. The re-growing hair is sometimes thinner and lighter improving the overall appearance.
Laser hair removal mechanisms
Hair removal uses two mechanisms. One uses an internal chromophore and the other an external chromophore.
Internal chromophore (melanin) mechanism
Ruby laser uses light of 694 nm wavelength. Reports about the treatment indicate that hair destruction is incomplete after the first treatment. Follow-up reports show that usually 20% to 60% hair reduction is attained after one or more treatment. In one case the hair reduction was only 13%, 7 months after four treatments. To improve treatment increase in pulse duration is being experimented.
Patients with dark hair respond best to the treatment. Better results are obtained from hairs on the face and axilla than on those on the legs and back. The treatment is not very effective on dark skinned patients.
Alexandrite laser uses a longer 755 nm wavelength compared to ruby laser. It therefore penetrates deeper into the dermis and is less absorbed by epidermal melanin, reducing the risk of epidermal damage, especially in dark skinned patients. Results are same as those of Ruby laser. After three to four months of several treatments 54% to 95% hair reduction was reported. After 6 months hair reduction of 33% to 34% was reported.
Diode laser: The device used in Diode laser is smaller and has a built-in cooling device. These features along with a longer wave length (800nm.) and increased pulse duration (5 - 30m.sec.) makes it safer for dark skinned patients. Hair reduction was 25% to 35% three months after one treatment and 34% to 53% 6 months after two treatments.
External chromophore (carbon suspension) mechanism
Neodynium: Yttrium-Aluminium-Gamet (Nd:YAG) treatment is the only well known treatment using this system. Carbon suspension as external chromophores replaces melanin. It is rubbed into the skin and enters the hair follicle. The carbon is irradiated by laser beam of 1064nm wavelength to generate the heat to destroy the follicle. All skin types can be treated with this system unlike lasers that target melanin.
Hair reduction is temporary. Three months after the first treatment 44% to 66% reduction was obtained. However, full re-growth occurred six months later.
Comparison with electrolysis
Compared to electrolysis, laser treatments are faster, less painful, less operator dependent and perhaps more effective. However, unlike in electrolysis, single hair or a small group of hairs cannot be targeted by laser.
Adverse effects of laser treatments
Most adverse effects are temporary and include commonly erythema and perifollicular edema and less frequently crusting and vesiculation of the site, hypopigmentation and hyperpigmentation. Their effect can be lessened by lightening the skin, avoiding the sun before and after treatment and cooling the skin during treatment.