ORLANDO, FLA. Topical application of a special agent to improve the optical properties of darker skin types appears to significantly improve the efficacy of laser-assisted hair removal with fewer epidermal side effects, according to data presented at the annual meeting of the American Society for Laser Medicine and Surgery.
By using an optical clearing agent to improve laser light penetration at the skin surface, "we believe that in darker skin types … types I-V … we can definitely improve laser hair removal," said Misbah Khan, M.D., a laser surgery fellow at the Beckman Laser Institute at the University of California, Irvine.
The optical clearing agenta polypropylene and polyethylene glycol mixturedecreases dermal scattering of light, thereby increasing laser light penetration. Once the optical clearing agent is applied to the skin, it is easier to see the dermal portion of the hair shaft, which led the researchers to suspect that it might also be easier to treat the hair.
In the study, the optical clearing agent was applied to one of each of 13 volunteers' underarms at least 2 hours prior to a single treatment with an alexandrite laser (GentleLase by Candela Corp.) in combination with cryogen spray cooling. The other side was treated with laser alone. Laser treatment was performed at various fluences depending on the volunteer's skin type, but both underarms of a single patient received the same fluence.
Hair counts in each area were performed before and 2 months after the procedure. Representative hairs also were clipped at the widest point of the base before and 2 months after treatment to determine hair diameter. In addition, the researchers assessed the areas for hyperpigmentation, hypopigmentation, and scarring.
"We were able to achieve more than a 70% reduction [in hair count] in a single treatment with the help of the optical clearing agent," said Dr. Khan. However, there was no significant difference in diameter between areas receiving the optical clearing agent and those receiving laser treatment alone.
In addition, with the use of the optical clearing agent, "we were able to substantially increase the depth and the extent of the thermal damage, and the immediate side effects of the laser-assisted hair removal were minimized to the degree that we didn't really see any," Dr. Khan said. A few volunteers required topical steroids for a day or 2 after the procedure on the side that did not receive the optical clearing agent.
Biopsies also were collected for histologic analysis. Cell viability stains were performed to assess the amount of thermal damage to the hair follicle. Hair follicles in areas treated with the optical clearing agent had much more evidence of thermal damage than did those in areas treated with laser alone.
The results are promising because even though several hair removal options are available for those who are considered to be good candidates, "there are limited treatment options available for people who are not good candidates, for example people with darker skin types and who also have dark hair," Dr. Khan said.
Longer wavelengths of laser light are one option because these do penetrate deeper. They are not well absorbed, though. Using shorter wavelengths instead typically leads to epidermal burns. The researchers believe that the optical clearing agent improves laser hair removal in patients with darker skin by allowing the use of shorter wavelengths while still avoiding dermal injury.