Slow pulse rate brings racial equality to cosmetic surgery

17 Jun 2002

Dermatologists from Massachusetts General Hospital (MGH) have developed laser techniques that safely remove hairs from darker skin. Dark skin contains more of the pigment melanin, which absorbs the energy from lasers and can cause side effects like color changes and scarring.

As with conventional cosmetic laser techniques, the method employs a pulsed infrared laser beam to destroy the roots of hairs by heating the melanin in their base. Prior to their research, pulse durations in hair removal lasers were usually 30 milliseconds or faster. To treat darker skin, the researchers slowed down the delivery of the laser pulses and are treating patients from 100 to 500 milliseconds. This allows the same amount of energy to be delivered to the hair roots more slowly, meaning that the skin surface cools more effectively between pulses, limiting heat damage.

The technique also includes concurrent, or parallel, cooling. The laser tip is set at 2-7 degrees centigrade so it is constantly removing heat from the surface of the skin at the same time as delivering energy to the roots of hairs. The system uses a 810 nanometer diode laser. Eliot Battle, a medical doctor at MGH, explains that melanin "likes this wavelength but doesn't love it, allowing us a chance to protect the epidermis."

Battle says that Coherent Medical, of Santa Clara, CA, and Palomar Technologies, of Lexington, MA have been following his research for the past 18 months and both companies will ship products based on the results within the next few months. "Coherent already has FDA approval and Palomar should receive it any day," he said.

"Many people will not treat people with darker skin because of the increased risk of side effects. Our technique will serve a population who've previously been largely ignored," said Battle. "The advancements we have made from this research can hopefully be used to for other laser applications, such as the removal of tattoos, scars and wrinkles, on dark skin." The latest MGH technique will also improve the effectiveness of laser treatment on people with fair skin.

SH

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