PHOENIX – Improvements in acne scarring were maintained 3 months after six laser treatments with a diffractive lens array and a picosecond 755-nm alexandrite laser. Changes seen on histology suggest the improvements stem from more than collagen remodeling alone.
Twenty adults with facial acne scars and Fitzpatrick skin types I-V underwent six laser treatments performed every 4-8 weeks at a single center using a 755-nm wavelength, diffractive lens array, pulse duration of 750-850 picoseconds, and repetition rate of 5 Hz, with a fixed spot size of 6 mm and fluence of 0.71 J/cm2.
Dr. Jeremy A. Brauer
Three physicians who were blinded to the results evaluated two- and three-dimensional images taken at baseline and at follow-up visits. Analysis of two-dimensional photos produced acne scar improvement scores averaging 1.5 at the 1-month follow-up visit and 1.4 at the 3-month visit on a 4-point scale (with 0 indicating 0-25% improvement and 3 indicating greater than 75% improvement), Dr. Jeremy Brauer and his associates reported.
Scar volume decreased by an average of 24% by 1 month post treatment and 27% by 3 months post treatment, according to analyses of the three-dimensional images, Dr. Brauer said at the annual meeting of the American Society for Laser Medicine and Surgery.
Histology of biopsy specimens taken at baseline and at 3 months after the last treatment showed elongation and increased density of elastic fibers, increased dermal collagen, and increased dermal mucin after treatment. These findings suggest that the improvements in scarring are caused by dermal changes beyond remodeling of collagen alone, said Dr. Brauer of the Laser & Skin Surgery Center in New York.
Dr. Brauer and his associates previously reported that the picosecond laser and diffractive lens array can improve acne scarring with minimal preparation and down time, "in many cases with no anesthesia at all," he said. The investigators offered topical anesthesia and antiviral prophylaxis to patients, but most declined.
The diffractive lens array delivers varying levels of heat at a fixed spot size and fluence. High-energy pulses that are 500 mcm apart deliver 70% of the fluence, with a lower level of heating surrounding these higher-level pulses. In total, approximately 10% of the tissue is exposed to the high-fluence regions.
The 15 women and 5 men in the study ranged in age from 27 to 62 years.
Previous methods of treating acne scarring with lasers, intense pulsed light, or other energy devices typically cause thermal injury that produces collagen synthesis and remodeling. Those procedures usually require anesthesia and can cause collateral damage that may take a long time to heal, he said.
The investigators chose the picosecond 755-nm alexandrite laser because it has been used successfully to remove tattoos or treat pigmented lesions while causing fewer side effects and coupled it with the specialized diffractive lens array.
The study excluded patients with hypersensitivity to light; localized or systemic infection, prior laser treatment in the past 3 months; and a history of skin cancer, keloidal scarring, immunosuppression, or immune deficiency disorder. Also excluded were patients who used isotretinoin in the past year and women who were pregnant, breastfeeding, or contemplating pregnancy.
Dr. Brauer and a coinvestigator reported financial associations with Cynosure, which also loaned equipment for the study.
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