Alexandrite Lasers

Several long-pulsed alexandrite lasers (755 nm) are being used for hair removal, including:

— Apogee series (Cynosure, Chelmsford, MA)

— Epitouch ALEX (Lumenis, Santa Clara, CA)

— GentleLase (Candela, Wayland, MA)

The Apogee system (Cynosure) provides pulse durations between 5 and 40 ms and fluences up to 50 J/cm2. A cooling handpiece (SmartCool) blows a continuous flow of chilled air into the treatment area. The scanner option (SmartScan) enables treatment of large areas with an unobstructed view, speedy treatment, and ease of use with minimal operator fatigue.

The Epitouch ALEX (Lumenis) delivers a 2-ms pulse duration, spot sizes of 5-10 mm, and fluences of 10-25 J/cm2. A cooling gel is applied to the skin before treatment, and a scanning device can be used to treat larger body-surface areas.

The GentleLase (Candela) delivers a 3-ms pulse duration, spot sizes of 8-18 mm, and flu-ences ranging from 10 to 100 J/cm2. It employs a dynamic cooling device (DCD) to protect the epidermis. The DCD cooling method uses short (5-100 ms) cryogen spurts, delivered to the skin surface through an electronically controlled solenoid valve; the quantity of cryogen delivered is proportional to the spurt duration.

There are a number of advantages in using long-pulsed alexandrite lasers for hair removal. Some of the long-pulsed alexandrite laser systems are compact and can be used in small rooms if adequate ventilation is available. Their flexible fiberoptic arm is easy to manipulate and provides access to hard-to-reach body areas. The large spot sizes and frequency (1-5 Hz) improves the possibility of rapidly treating large body areas.

The alexandrite laser wave length of 755 nm is absorbed about 20% less strongly by melanin compared with the ruby laser wavelength of 694 nm. Its absorption by the competing chro-mophore, oxyhemoglobin, is substantially increased as compared to the 694-nm wavelength. However, the longer wavelength of 755 nm penetrates more deeply into the dermis and is less absorbed by epidermal melanin. This theoretically decreases the risk of epidermal damage, especially in individuals with darker skin types.

Because dermal scattering decreases with increasingly longer wavelengths, 755-nm light penetrates deeper into tissue than does shorter wavelengths. In theory, the use of longer wavelengths should increase the ratio of energy deposited in the dermis relative to the epidermis. This would result in relatively increased bulb heating while at the same time promoting epidermal sparing (Ross et al. 1999).

The reported hair removal success rate using an alexandrite laser has ranged from 40% to 80% at 6 months after several treatments (Gorgu et al. 2000) In a controlled randomized study using a single 20 J/cm2, 5- to 20-ms alexandrite laser on various anatomic sites, investigators reported a 40% reduction in hair growth 6 months after treatment. This increased to >50% (on the upper lip) if a second treatment was performed after 8 weeks. In another study, one treatment with a variable pulsed alexandrite laser produced maximum hair growth reduction at 6 months of 40%-56% for the lip, leg, and back. Finally, one study has noted a mean 74% bikini hair reduction 1 year after five alexandrite laser treatments.

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