Aesthetic Dermatology

Authors of picosecond laser review predict more widespread use of the technology



Ever since the first picosecond laser hit the market in 2012 as an option for treating unwanted tattoos and pigmented lesions, clinicians have used the technology to safely and effectively treat an expanding range of dermatologic conditions, from Nevus of Ota and melasma to rejuvenation.

In an exhaustive systematic review published online April 13 in Lasers in Surgery and Medicine (2020. doi: 10.1002/lsm.23244), experts from Cosmetic Laser Dermatology in San Diego, Calif., and the Wellman Center for Photomedicine at Massachusetts General Hospital in Boston crafted evidence-based recommendations for using picosecond lasers, which currently feature pulse durations between 300 and 900 picoseconds. They called for further development of the technology and predicted that application of the devices will become more widespread.

Dr. Douglas C. Wu

“Future directions may include the development of even shorter pulse durations, improvements in fractionation method and delivery, and exploration of the utility of pulsing other laser wavelengths in the picosecond (or shorter) domain,” first author Douglas C. Wu, MD, PhD, of Cosmetic Laser Dermatology and colleagues wrote in the review. “The introduction of newer devices along with continued improvements in clinical technique and experience will drive the refinement and expansion of this technology.”

The authors evaluated medical literature on the topic published up to March 2020 and classified 78 studies into one of the following categories: discrete pigmented lesions, other nonmelasma pigmented conditions, rejuvenation, melasma, scar revision, and tattoo removal. They assessed the level of evidence for each indication according to modified criteria published by the Oxford Centre of Evidence-Based Medicine and proposed recommendations based on the medical literature in combination with the authors’ collective clinical experience with picosecond laser.

In the category of discrete pigmented lesions, the authors assigned level of evidence 1a to Nevus of Ota and Hori’s macules, level of evidence 2b to solar lentigines and freckles, level of evidence 3c to café au lait macules, and level of evidence 4 to all other benign pigmentary conditions. “Comparative studies utilizing clinical, histological, and microscopic endpoints further suggest that picosecond laser may be safer and more effective than nanosecond laser in some situations, with potentially reduced risk of inducing postinflammatory hyperpigmentation,” the authors wrote. “This increased safety level may be due to the reduction of non-specific photothermal damage of the melanocyte and dermal-epidermal junction,” they noted. They called for more robust clinical comparative data with a focus on shorter pulse durations and refined clinical endpoints “to further distinguish the differences between picosecond and nanosecond laser for the treatment of some benign pigmented lesions.”

Based on seven prospective open-label trials and three split-face comparison trials involving the use of picosecond lasers for photorejuvenation, the authors assigned a level of evidence 2a to this category. “The studies show a high level of safety associated with a moderate level of efficacy,” they wrote. “Indeed, when compared with traditional non-ablative fractional laser, fractionated picosecond laser may have an improved side effect profile without sacrificing treatment efficacy. This could be due to the unique mechanism of action of fractionated picosecond laser, which results in greater confinement of tissue injury to focal and precise points within the epidermis and papillary dermis.”

Clinical data on using picosecond lasers to treat melasma remains “mixed and unclear,” but it may have a role as an adjunctive treatment combined with rigorous photoprotection, topical melanin inhibitors, “and potentially other laser or systemic therapies as dictated by clinical circumstance,” the authors said. They do not recommend the picosecond laser as a monotherapy for melasma, and they assigned a level of evidence 2a to this category.

Although the fractionated picosecond laser is cleared by the Food and Drug Administration for the treatment of acne scars, Dr. Wu and his colleagues noted that rigorous clinical data on using the technology for this indication is limited. “Encouragingly, reports thus far seem to suggest that the risk of post-inflammatory pigmentary alteration is low when using fractionated picosecond laser, which has added significance due to the high prevalence of acne scarring in skin of color,” they wrote. They assigned a level of evidence 2b to this category. Meanwhile, clinical data on the use of picosecond lasers for non-acne scars are limited to cases series and retrospective reviews, reaching evidence level 3c. “Although the level of evidence is weak, there is likely an effective role for fractionated picosecond laser for the improvement of hyperpigmented scars given its more robust track record for the treatment of hyperpigmentation due to other causes such as benign pigmentary conditions and photodamage,” the authors wrote.

The manuscript concludes with a discussion of the picosecond laser’s role in tattoo removal, which represents the oldest and most established dermatologic indication for the technology. “The accumulated scientific and clinical evidence to date concludes that the shorter pulse duration confers a distinct advantage when other laser parameters remain equal,” the authors wrote. “The evidence also suggests that the shorter the pulse gets (within currently commercially available and tested devices), the greater becomes the efficacy for tattoo removal. There is no evidence to suggest that larger tattoo particles are more optimally targeted by longer nanosecond pulses.” They assigned a level of evidence 1a to this category and described using the picosecond laser for tattoo removal of almost any color as “the gold standard.”

Dr. Arisa E. Ortiz

In an interview, Arisa Ortiz, MD, described the manuscript as a thorough review of the clinical indications for picosecond lasers. “Overall, the review shows evidence for slightly better improvement of efficacy with picosecond lasers compared to nanosecond lasers,” said Dr. Ortiz, director of laser and cosmetic dermatology at the University of California, San Diego, who was not involved with the review. “They also show a slightly improved side effect profile with picosecond lasers [and] notably, less risk of postinflammatory hyperpigmentation in darker skin types compared to nanosecond lasers. One issue that was not addressed was the cost of picosecond lasers. The cost of a picosecond lasers remains substantially higher than the cost of a nanosecond laser. I am not sure that this extra cost justifies a slightly improved efficacy or slightly improved side effect profile.”

Dr. Eric Bernstein

According to Eric F. Bernstein, MD, director of the Main Line Center for Laser Surgery in Ardmore, Penn., the versatility of picosecond lasers offers an advantage to dermatologists. “Most of them have three wavelengths at least,” said Dr. Bernstein, who was not involved with the systematic review. “That means you can treat skin types I-VI. I was never able to offer much for my patients with skin types V and VI for fractionated rejuvenation and treatment of acne scarring. But now, with these lasers, I have an option for them. That’s a huge advantage.”

He credited laser engineers as “the real heroes” in the success of picosecond lasers in dermatology. “They’re passionate, they’re brilliant, and they’re creative,” Dr. Bernstein said. “They’re the ones that build and produce these devices for multiple manufacturers. In our space, the innovation really comes from industry.”

The review authors and Dr. Ortiz reported having no relevant disclosures. Dr. Bernstein disclosed that he is head of Candela’s medical advisory board.

SOURCE: Wu DC et al. Lasers Surg Med. 2020. doi: 10.1002/lsm.23244.

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