1,450 nm diode laser cuts sebum production

Boston - A small study appears to confirm the 1,450 nm diode laser's suspected mechanism of action in treating acne: reducing sebum production.

"Most previous studies using the 1,450 nm diode laser (SmoothBeam, Candela) have focused on its effect on acne vulgaris and sebaceous glands," says Adrian Perez-Maldonado, M.D., a Monterrey, Mexico, dermatologist in private practice who served as the study's lead author while at Boston University's dermatology department.

However, he says that although researchers have proven the laser's impact on sebaceous glands, "No one really addressed sebaceous output."

To fill this information gap, Dr. Perez-Maldonado and his colleagues recruited four male and four female subjects, ages 25 to 42, with Fitzpatrick skin types II through IV and a history of mild-to-moderate acne vulgaris.

They excluded patients with severe acne vulgaris; presence of nodules, cysts or fistulas; history of oral isotretinoin or acitretin use during the previous six months; or prior adverse reactions to lasers.

Before each laser treatment, investigators took a total of five sebum measurements on each side of the nose over a six-week period, using the Sebutape (CuDerm Corp.) method. This involved washing and degreasing both sides of the nose and firmly applying the Sebutapes, which Dr. Perez-Maldonado says are made of a lipid-absorbing polymeric film, for 30 minutes.

"This method has been proven reliable for sebum quantification," Dr. Perez-Maldonado says.

Along with being easy to use, he says the Sebutape allowed for photographic image analysis.

To measure collected sebum, researchers photographed Sebutapes against a black background under consistent lighting and focal conditions. They then analyzed these images using ImageJ software (open source, public domain: http://rsb.info.nih.gov/ij/), which counted both the number of sebum-producing follicles and the area or volume of sebum absorbed into the tape. To assess the accuracy of measurements, researchers later compared left and right values for baseline sebum counts and areas and found they varied by 2.1 ± 7.2 percent and 4.9 ± 8.4 percent, respectively.

LIGHTING THE WAY

After establishing the baseline for sebum production, researchers performed three treatments, spaced two weeks apart, on the right side of each patient's nose with the 1,450 nm diode laser.

They used a 6 mm spot size, a fluence of 12.5 J/cm² and no overlap in order to minimize patient discomfort and standardize treatment as much as possible, Dr. Perez-Maldonado tells Dermatology Times.

Bilateral sebum measurements preceded each session, and immediately after each treatment, investigators also measured sebum production as described above. Six weeks after the initial treatment, researchers performed only bilateral sebum measurement.

To compare treated versus untreated areas, investigators performed Student's t-test at various time points. They found a statistically significant reduction in the number of sebum-producing follicles at weeks four and six (16.7 percent and 15.9 percent, respectively; Lasers Surg Med. 2007 Feb;39(2):189-192). The maximal effect was a statistically significant reduction in sebum output of 18 percent after three treatments, Dr. Perez-Maldonado adds.

"We found that the 1,450 nm diode laser does seem to have an effect on sebum production. This laser acts through bulk heating of the dermis, which, in turn, appears to damage the sebaceous glands," he says.

As such, he says the laser provides a satisfactory alternative for patients with mild-to-moderate acne and those with adult-onset acne who can't take or haven't responded to systemic treatment.

"Patients with more severe acne, such as nodulocystic acne, will probably need systemic treatment, such as isotretinoin," Dr. Perez-Maldonado says.