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Pixel by pixel

Article-Pixel by pixel

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  • The laser pixel technique offers results that are comparable to those seen with ablation therapy, according to one expert

Dr. Keller
Los Angeles Last April, Alma Lasers launched the Pixel 2940 module for the Harmony laser platform, which splits the laser beam, establishing a means to achieve skin resurfacing via fractional ablation therapy. The skin is exposed to the laser as a grid of discrete "pixels" rather than as a uniform layer over a broad area. "The wonderful thing about using the Erbium YAG 2940-nm laser is that Alma is exploiting a technology whose effects as an ablative treatment are already familiar to cosmetic surgeons," Gregory S. Keller, M.D., F.A.C.S., tells Cosmetic Surgery Times . "Without being encumbered by a new treatment variable, the surgeon can focus on how to maximize the efficacy of the pixel technique to achieve results that are comparable to those seen with ablation therapy. Although the efficacy of fractional ablation used alone is less dramatic than conventional ablation therapy, what makes this technique worthwhile is its association with rapid healing and few adverse effects. Patients experience little or no pain during treatment, continue with their daily life on the same day, and total post-treatment effects consist of three to four days of sunburn-like redness and slight flaking." Dr. Keller, who is an associate clinical professor of surgery at the University of California at Los Angeles (UCLA) and director of the facial plastic surgery fellowship at UCLA, has been working with the Alma pixel laser for almost one year and has treated approximately 80 patients to date with this technique.

PATTERNED FOR HEALING The pixel laser creates a square pattern of 49 (7 X 7) or 81 (9 X 9) microscopic wounds (pixels), each approximately 50 μm wide, producing a relatively equal ratio of ablated tissue to healthy tissue. Healing of the injured tissue results in smoother, tighter skin due to shrinkage of dermal collagen. The healthy tissue enables rapid healing by providing a reservoir of new viable epidermal stem cells. The 49-pixel microbeam delivers approximately 28 mJ/pixel for deeper penetration, whereas the 81-pixel microbeam delivers approximately 17 mJ/pixel. "We make one pass over the whole face, then additional passes over selected areas," Dr. Keller explains. "The whole process takes 10 minutes."

(Left) Before pixel treatment. (Right) Two weeks after second pixel treatment. Treatment consisted of two full-face passes with 7 x 7 pixel tip at 1400 mJ/pulse, 2-m pulse duration. Photo credit: Alma Lasers, Ltd.
While no anesthesia is necessary, Dr. Keller typically pretreats patients with glycolic or vitamin C-based serum. Patients previously treated with retinols may continue with these products. All laser treatment is based on titration, whether that be an escalating or a declining dose response. MORE LATITUDE Although his initial approach started with the 81 pixel less-aggressive mode, Dr. Keller's current approach is to begin with 49 pixels, recognizing that the rapid healing associated with the pixel method affords the possibility of being more aggressive. The ideal candidate for resurfacing has a Fitzpatrick skin type between 1 and 3 (the lighter, more sensitive skin type) because of a decreased risk of scarring or keloid formation. Therefore, an aggressive approach is appropriate for these light-skinned patients. According to Dr. Keller, types 4 to 6 (olive-skinned patients or darker) should be treated more cautiously due to increased scarring risk.

Pixel Pattern: Spot size: 11 x 11 mm/81 pixels, 9 x 9 pattern Photo credit: Alma Lasers, Ltd.
MULTI-MODALITY Ablative resurfacing produces more therapeutic injury than that caused by fractional ablation. However, when fractional ablation is combined with another modality, the efficacy of the two approaches becomes comparative. Furthermore, the duration of post-treatment erythema after pixel laser therapy extends from four to six days, bearing no resemblance to the prolonged erythema associated with ablative resurfacing, which can endure for as long as one year after treatment.

"It's a challenge to coordinate the incomplete knowledge patients acquire from sources such as the Internet with practical considerations such as skin type and the potential benefit of multiple modalities," notes Dr. Keller. "For 95 percent of cases, a combination of pixel laser therapy with other modalities is a preferable approach to skin resurfacing, compared with ablative laser therapy." Pixel laser therapy is most often combined with intense pulsed light (IPL) as a series of treatments, with repeat treatment recommended at six months or one year. More aggressive ablative treatment is reserved for very severe cases with re-treatment scheduled at a frequency of several years. However, the interim period is maintained using nonablative techniques.

STACKED EXPOSURE For deeper wrinkles, Dr. Keller uses "a combination of longer-lasting filler substances with the pixel, IPL and skin-tightening Alma machinery. Laser exposure can be stacked," Dr. Keller points out, "although stacking is generally used only to treat deep wrinkles." Alma's Harmony machinery has interchangeable heads — one for pixel laser therapy, another for IPL, another for skin tightening — that make combination treatments affordable for both the physician and patient. Similar trends are being seen with other companies who provide technology for cosmetic surgeons.

APPLES TO APPLES Clinical trials to illuminate the effects of pixel therapy are difficult to run because of the inevitable use of a variety of modalities on a single patient. How do you assess the individual effect of each modality? According to Dr. Keller, it is as much an art as a science. Dr. Keller is currently involved in a study of approximately 80 patients to evaluate patient satisfaction and wrinkle disappearance. Follow-up will extend to one year post-treatment. He is conducting another study that will compare microscopic changes with those of ablational resurfacing.

Ideally, future studies may tell us more about the effect of pixel therapy on the characteristics of individual patients, for example, hyperkeratosis within the excised areas of facelift skin.

It is likely that the future of this technology will include the application of more energy, an increase in the number of passes employed per treatment cycle, expansion of the wavelengths utilized, definition of optimal titration strategies, and identification of the therapy combinations that work best.

For more information
Gregory S. Keller, M.D., F.A.C.S.
[email protected]

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