Laser hair removal and vein ablation

Laser hair removal

Many postpubertal patients have unwanted hair and practice hair removal of some form. Common temporary methods of hair removal include waxing, plucking, shaving, and depilation. Temporary methods can last weeks to months, with waxing generally lasting the longest at 2 or 3 weeks longer than the others. While these methods are typically temporary, they may incidentally damage the dermal papilla causing minimal permanent removal of hair.

Permanent hair reduction has been defined as a significant reduction in the number of terminal hairs after a given treatment, which is stable for a period of time longer than the complete growth cycle of hair follicles at the given body site. Permanent methods of hair removal include electrolysis, laser therapy, or intense pulsed light (IPL) therapy. Electrolysis is labor intensive, and its efficacy largely depends on application of correct technique. Laser hair removal may be a superior choice for long-term hair removal as it is more effective, faster, and less painful ( Fig. 6.1 ).

There are several wavelengths, measured in nanometers (nm), of lasers available for hair removal. They include the ruby laser (694 nm), alexandrite laser (755 nm), diode laser (800 nm), and neodymium : yttrium-aluminum-garnet (Nd : YAG) laser (1064 nm). Separately, intense pulsed broadband light sources (590–1200 nm) can also be used for hair removal. Lasers are considered photoepilation therapies that reduce hair through selective photothermolysis. Selective photothermolysis is a technique that asserts that applying a brief laser pulse to a pigmented target will generate and confine heat to that pigment as long as the laser penetrates deep enough, and the target has greater absorption than its surrounding tissue at a specific wavelength. The pulse should be brief and targeted such that the temperature exceeds that required to denature the pigmented target, in this case melanin in the hair bulb, without heating the surrounding tissue above its denaturing point. Surrounding tissue often contains structures that may absorb the laser energy, such as skin pigment, which may lead to adverse effects or decrease the efficacy of the treatment.

The wavelength of the laser should be selected so that it is only absorbed by the melanin in the hair bulb and based on the desired depth of laser penetration. The main sources of interference for absorption in the hair are melanin in the skin and oxyhemoglobin present within blood vessels. However, it has been shown that a wavelength of 700 nm is selectively absorbed by melanin and, in turn, specifically destroys the hair follicle, leaving the blood vessels chiefly intact. The longer the wavelength of the laser, the deeper penetration into the skin and the lower affinity for absorption by surface melanin. This allows for more selective absorption by the melanin in the hair bulb rather than epidermal melanin.

Adequate cooling between pulses is required to reduce epidermal injury and associated adverse events such as change in pigmentation and blister formation, especially individuals with darker phototypes. Cooling can be achieved through application of ice, application of a cooling gel, application of pulsed cryogen spray (dynamic cooling device [DCD]), or through addition of a contact cooling window attached to the handpiece of the laser. Cooling pieces include a sapphire handpiece or a cooled glass chamber.

Laser hair removal, regardless of the laser used, creates pinprick or rubber band snapping against the skin sensation because of heat. That, in combination with the different pain thresholds throughout the body, results in areas of greater or lesser sensitivity to laser treatment. The most sensitive areas include the bikini line and axilla, while the legs and arms are generally much less painful.

Laser vein ablation

Venous insufficiency can present with a variety of clinical symptoms ranging from superficial telangiectasia to chronic venous disease with severe skin ulceration. Treatment options include thermal or nonthermal vein ablation, sclerotherapy, or vein ligation and stripping, the latter of which are typically reserved for more severe disease and are associated with higher postoperative complications. When treating more superficial telangiectasias and varicose veins, sclerotherapy and thermal or laser vein removal are more appropriate treatments.

For the purpose of this text, we will discuss laser vein removal, as it is the most minimally invasive treatment option for cosmetic vein removal. It is most effective for telangiectasias, reticular veins, and small varicose veins. Specifically, laser or light vein therapy is optimal for use on vessels 1 to 2 mm in diameter, but it can be used for vessels as large as 4 to 5 mm.

Like laser hair removal, laser vein treatment applies selective photothermolysis. However, in the case of laser vein ablation, the target pigment is oxyhemoglobin rather than melanin. To target the oxyhemoglobin, a laser with the appropriate wavelength must be selected to avoid interference with competing melanin in the skin and hair. Specific lasers used for vein ablation target oxyhemoglobin using three broad absorption peaks at 418, 542, and 577 nm, or smaller peaks at 920 to 940 nm and 1064 nm. The heat causes coagulation and collapse of the vein, resulting in decreased visualization of the vein and redirection of the blood flow through collateral vessels. Common lasers used on vascular lesions are long pulse lasers, including the potassium titanyl phosphate (KTP) (532 nm), pulsed dye laser (PDL) (585–595 nm), alexandrite laser (755 nm), diode laser (800 nm), Nd : YAG (1064 nm), and the IPL source (590–1200 nm). Similar cooling requirements, including use of cryogen spray, sapphire handpieces, chilled air or water, are needed for laser vein ablation as with laser hair removal. The pain associated with treatment is typically described as a pinching or stinging sensation.