News Release

MGH dermatologist develops new laser techniques to safely remove hair from darker skins

Peer-Reviewed Publication

Massachusetts General Hospital

A dermatologist from the Massachusetts General Hospital (MGH) announced today that he has been able to remove excessive hair successfully and safely from people with darker ethnic skin using new laser equipment and techniques. Until now all types of laser skin treatment have been ruled out for individuals with dark skin because of the risk of side effects.

Speaking at the meeting of the American Academy of Dermatology (AAD), Eliot Battle, MD, of the MGH Wellman Laboratories of Photomedicine, described how the use of a diode laser, which delivers long-wavelength laser light, has produced positive results in either delayed hair regrowth or permanent hair reduction among volunteers from a wide range of ethnic groups.

"Many people of color have medical conditions related to hair growth," said Battle. "Hirsuitism, excessive growth of hair on any area of the body, is more common in darker-skinned men and woman. Shaving can cause men with tightly coiled hair to develop painful ingrown hairs or 'beard bumps.' More traditional means of hair removal - like plucking, waxing and electrolysis - can lead to hyperpigmentation [dark spots] in people with darker ethnic skin. We believe that anyone who desires to improve appearance by removing unwanted hair should be able to take advantage of laser hair removal."

The use of lasers to remove hair, pigmented lesions or tattoos is based on the fact that pigments selectively absorb particular wavelengths of light. This basic concept and the resulting medical technologies were discovered and developed by Battle's Wellman Labs colleagues R. Rox Anderson, MD, and John Parrish, MD, director of Wellman Labs and MGH chief of Dermatology. Current laser hair removal techniques use wavelengths of light that target melanin, the pigment that determines color of both hair and skin. In light-skinned people, the laser energy safely passes through the skin and is absorbed by the darker hair shaft, attempting to destroy the hair and its root. Because darker-skinned people have more melanin in their skin, those wavelengths would also be absorbed by and damage the skin.

The technique developed through the research of Battle and Anderson uses a diode laser, which emits light at a longer wavelength than does the traditional ruby laser. The longer wavelength is less readily absorbed by melanin, which has some protective effect. However, Battle also has discovered that using a longer exposure time affords even more protection to dark skin. Older lasers might deliver a given amount of laser energy (a measure called fluence) in less than 30 milliseconds, while newer equipment can spread that energy delivery out over 100, 500 or even 1,000 milliseconds. These longer pulses lessen the amount of energy passing through the skin at a specific moment, allowing the skin to be cooled more effectively and enabling all patients - including those with darker ethnic skin - to tolerate a higher total energy dosage.

These features not only protect the skin cells adjacent to the treated hairs, they also allow energy to be targeted to hair stem cells located near the top of the hair follicle; recent studies suggest that these stem cells signal cells in the hair root to grow. "Because this slower release of energy doesn't vaporize the hair shaft, as short-pulse laser treatment does, the energy is passed to the stem cells, which otherwise would remain unaffected," Battle explained. He added that, as with any new technology, physicians using lasers to treat people with ethnic skin must receive appropriate training.

Battle is completing an 18-month study of the use of a very-long-pulse diode laser for hair removal in 84 patients from 20 ethnic groups, with skin tones ranging from quite fair to very dark. Preliminary data from that study will be presented April 8 at the American Society for Laser Medicine and Surgery Meeting in Reno, Nev. Battle's research is supported by Palomar Medical Technologies Inc.

Founded in 1974, the Wellman Laboratories of Photomedicine are widely regarded as a world leader in investigating the interactions between light and living tissues. Today's laser medicine applications have been developed from fundamental discoveries made at Wellman Labs. Among the many medical laser treatments developed at Wellman are removal of port wine stains, tattoos, spider veins and pigmented lesions; laser treatment of kidney stones, glaucoma, and macular degeneration; and laser skin resurfacing and hair removal. Also developed at Wellman labs were light-based PUVA treatment for psoriasis and the use of special light-activated drugs to treat cancer and other conditions. Wellman scientists are members of the Center for Innovative Minimally Invasive Therapy (CIMIT), based at the MGH, and collaborate with researchers at Massachusetts Institute of Technology, Harvard University and other research institutions.

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