Ethnic skin: laser treatments require adjustments

"At one point a few years ago, laser manufacturers virtually ignored dark-skinned people and believed these technologies could not be used to treat them," Khalil Khatri, M.D., says.

However, Dr. Khatri, who is medical director of Skin and Laser Surgery Center of New England, with offices in Chelmsford, Mass., and Nashua, N.H., says the current generation of laser technology is built in a way that allows physicians to change settings so that they can treat darker-skinned patients.

And manufacturers' increasing attention to darker-skinned patients has boosted the popularity of laser and light treatments worldwide, he adds.

Idiosyncrasies of darker skin

Compared to lighter skin, the epidermis of darker-skinned patients possesses increased melanin (but the same number of melanocytes) and larger, more melanized melanosomes, which degrade more slowly than those of fair-skinned patients, Dr. Khatri says.

Because of these factors, he says, "Darker skin absorbs and scatters more UV light, which gives dark-skinned patients better photoprotection. This results in less photodamage, skin cancers and wrinkles" than Caucasian patients typically experience.

However, Dr. Khatri adds, "The dermis itself is also thicker in darker skin, and the mesenchymal activity within the dermis is higher, which leads to greater risk of developing hypertrophic and keloidal scars."

Accordingly, he says that if one treats dark-skinned patients with the same settings as one would use for Caucasian patients, the increased amount of melanin within the epidermis of the darker-skinned patients means their skin would absorb more energy and suffer more complications - namely, hyperpigmentation, hypopigmentation or depigmentation - as a result.

Cool it

To avoid these problems, common cooling techniques include use of gel packs, ice packs and cryogenic sprays, all of which physicians typically employ before and, if desired, after treatment, Dr. Khatri notes.

"Contact cooling is probably the best way, because it allows one to cool the area being treated before treatment, during treatment and right after treatment," he says.

Contact cooling mechanisms include water-based systems and sapphire crystals.

With such mechanisms, Dr. Khatri says, "One can parallel cool as well - while one is delivering the pulse - because the pulse is going through the sapphire crystal, which is already making the epidermis cold."

One also can lower energy levels to make treatments safer for darker-skinned patients, although this practice decreases efficacy, he says.

In contrast, he says, "Cooling helps in two ways - it reduces the risk of complications and allows us to use higher energy settings, which can provide better efficacy."

Furthermore, Dr. Khatri says that with most laser devices, "We use a longer pulse when treating darker-skinned patients."

He likens this practice to pouring a pail of water slowly - which allows heat energy to dissipate during treatment - as opposed to dumping it all at once.

Regarding wavelengths, he says that for applications such as hair removal, 1,064 nm Nd:YAG lasers and intense pulsed light (IPL) devices (near the higher end of their 500 nm to 1,200 nm range) probably are safest for dark-skinned patients.