Use of a fractional 1570‐nm diode laser scanner for non‐ablative face and neck rejuvenation

The use of non‐ablative fractionated lasers for skin rejuvenation has been proven to be effective in improving skin texture, and has become popular due to minimal wounding, significantly shorter recovery times and decreased adverse effects.


| INTRODUC TI ON
Skin laxity is affected by various extrinsic and intrinsic aging processes.Extrinsic skin aging is caused by long-term exposure to pollution, ultraviolet (UV) radiation, and wind; various lifestyle habits, such as smoking, sleeping or diet, as well as repetitive muscle movements (e.g., squinting, frowning).Extrinsic skin aging is characterized by the degradation of collagen and accumulation of large amounts of abnormal elastin, which contributes to the loss of elasticity, 1 as well as increased intercellular substance and moderate inflammatory infiltrate. 2,3Intrinsically aged skin is characterized by an atrophic epidermis and dermis.Lower vascularity, decreased numbers of dermal elastic fibers and fibroblasts, and a gradual decline in dermal extracellular matrix proteins, such as collagen and hyaluronic acid due to lower biosynthetic capacity, all lead to impaired skin function and fragility.Consequently, the volume and support of dermal structures decline, resulting in reduced skin torsion extensibility and wrinkling of the overlying epidermis. 1,4ver the years, many technologies have been developed for reducing the signs of aging and rejuvenating the skin.[7][8] The first consideration in the selection of wavelength is to determine the target chromophore and the target penetration depth. 9e primary chromophore for tissue stimulation is water, which is present throughout the tissue. 10The absorption spectra of melanin and hemoglobin fall largely in the UV to near infrared (IR) range with different absorption peaks. 11Therefore, the preferred choice for skin rejuvenation would be wavelengths outside the UV to near IR range.
Penetration depth is a function of the absorption and scattering properties of the wavelength, with higher absorption resulting in less tissue penetration.In general, in the UV to near-IR spectrum, longer wavelengths penetrate deeper.Beyond this range, water, as a primary chromophore, has different absorption levels that affect the penetration depth of different wavelengths.Some resurfacing devices, such as erbium and carbon dioxide lasers (2940, 10 600 nm), use far-IR wavelengths, that are highly absorbed by water, to remove epidermal tissue while avoiding deep tissue penetration. 10Although highly effective, persistent side effects and complications have been reported with these ablative laser resurfacings.Most non-ablative lasers emit mid-IR wavelengths for deep tissue penetration.They target dermal water to heat collagen and promote dermal remodeling, while sparing the epidermis.Indeed, clinical studies have shown significant improvements in facial wrinkles, atrophic acne scars, hypertrophic scars, and enlarged pores when treated with various non-ablative fractional laser systems, including Nd: YAG (1440 nm), diode (1440 nm), erbium glass (1410, 1540, and 1550 nm), and thulium (1927 nm) systems. 12wever, these wavelengths penetration depth varies due to differences in water absorption properties.Wavelengths between 1400 and 1500 nm and above 1850 nm are highly absorbed by water in the superficial layers of the skin, which can cause epidermal damage. 13other influencing factor is fractional photothermolysis, a technique that selectively removes only a fraction of the skin. 12actional photothermolysis utilizes wavelengths that target the water in the skin in a non-ablative manner.The laser beam is manipulated through a set of mirrors and lenses, creating different patterns of multiple microscopic laser beams (pixels).Each pixel creates a small column (less than 400 μm in diameter) of thermal damage, called microscopic thermal zone (MTZ), whose penetration depth are proportional to the laser energy emitted, and can reach over a 1000 μm in depth.The laser thermally denatures dermal collagen, but spares the stratum corneum, keeping the skin's barrier function intact.The undamaged tissue between the MTZ serves as a reservoir of healthy, viable tissue that aids in the repair of the coagulated MTZ, facilitating repair and remodeling of the epidermis and dermis. 14[17] The purpose of this study was to assess the improvement in skin texture for moderate skin laxity in healthy women over 18 years of age with Fitzpatrick skin types I-IV using a 1570-nm non-ablative fractional fiber laser.

| Settings and participants
Healthy women aged 35-50 demonstrating moderate skin laxity or wrinkles were enrolled.Women excluded from the study were individuals suffering hormonal disorders or other diseases that are stimulated under pulsed light (specifically 1570-nm light), cancer, any history of keloids or hypertrophic scarring, active herpes simplex infection in the treatment area or had prolonged exposure to the sun or to an artificial tanning machine in the 3-4 weeks prior to the treatment.Women were also excluded if they were taking oral or topical retinoids or steroids, or other medications, herbal supplements to which exposure to 1570-nm light is contraindicated.
The study was conducted in accordance with the Declaration of Helsinki, and all participants provided signed informed consent prior to treatment.

| Treatment
Participants received facial and/or neck treatments using the Alma Hybrid (Alma Lasers, Caesarea, Israel) platform, which utilizes a 1570-nm non ablative fiber laser via the Proscan scanner applicator in its "SoftLift" mode of action.
Prior to each treatment, topical numbing with lidocaine/prilocaine 5% ointment or lidocaine 18% was applied for 40 min to the treatment area.The treatment area was then cleaned and disinfected thoroughly.Treatment consisted of three treatment sessions at monthly intervals using the following settings: Power level of 10.5-12 W with pulse duration of 3-5 ms and a density of three.
Follow-up was conducted 3 months after the last treatment session.The participants were asked to rate their satisfaction with the treatment using the question: "How pleased are you from the treatment?"Their answers were provided using the following scale: 0 = extremely unhappy; 1 = unhappy; 2 = happy; 3 = extremely happy.

| Assessments of outcomes
They were also asked if they would recommend the procedure to a family member or a friend.
To evaluate pain and discomfort associated with the laser treatments, the participants were asked to rate their general pain and discomfort level immediately after each treatment using a visual analogue scale (VAS) ranging from 0 (no pain) to 10 (intolerable pain).Downtime following procedure was assessed at each subsequent visit and adverse events were monitored during all the visits.

| Statistical analysis
Data were analyzed using descriptive statistics.Categorical values were summarized using number and frequency and continuous variables were summarized using mean and standard deviation (SD).Continuous variables were compared using Student's t-test.
Statistical significance was considered at p < 0.05.

| RE SULTS
Sixteen women with a mean age of 45. in face and neck treatments, respectively.Moreover, VAS score decreased with each treatment session as indicated in Figure 7B.
VAS score was statistically significantly lower at the last treatment session compared to the first session in both treatment areas (neck: 2.71 ± 0.49 vs. 3.57 ± 0.98, p = 0.017; face: 2.44 ± 0.73 vs. 3.00 ± 1.00, p = 0.003).Mean pain VAS at each treatment session was slightly higher in the neck area compared to the face.
There were no adverse events reported by any of the patients.All reported no significant downtime, as they returned to their daily routine immediately after each session.

| DISCUSS ION
Our results demonstrate that a series of three treatments with a 1570-nm non-ablative fractional scanning laser improved skin laxity  The 1570-nm fiber laser has only been recently put into clinical use; therefore, there is only limited information about its efficacy.
Non-ablative lasers that emit wavelengths within close range of the 1570-nm laser and are also used for facial rejuvenation and toning improvement include the 1565-nm, 16,[19][20][21][22] the 1550-nm, 15,17,[23][24][25] and the 1540-nm [26][27][28] non-ablative lasers.By avoiding wavelengths of 1400-1500 and above 1850 nm, where high water absorption limits penetration depth, these devices allow for deep tissue penetration. 13This is especially valuable for individuals with darker skin types, who are more susceptible to scarring from surface ablation 29 due to higher melanin content in the epidermis. 10e of these lasers has shown excellent outcomes with minimal risk and morbidity for a variety of clinical conditions, including photo damaged skin, 15,16,21,23,24,26 atrophic scars, [30][31][32] surgical and burn scars. 33,34,28 Water is the main chromophore for these wavelengths. 15Skin remodeling with non-ablative lasers is achieved by heating the F I G U R E 8 Wound healing process following 1570 non-ablative fractional laser irradiation in vivo.
Digital photographs were standardized and taken using the same camera (Canon EOS 2000D) fixed at an 18 mm zoom on a fixed tripod with fixed illumination (GodoxML60, two flash LEDs), at baseline (prior to treatment) and at the 3-month follow-up visit.Outcome assessments were performed by two blinded evaluators, who assessed the changes in the neck and face laxity and appearance using the following scale: 0 = worse; 1 = no clinical change; 2 = minor change; 3 = visible change; 4 = obvious change; 5 = significant change.

7 F I G U R E 1
Figures 2-6.Mean pain sensation was low in both face and neck treatments as demonstrated in Figure 7A, VAS scores (average of three treatments calculated for each subject) were 2.7 ± 0.8 and 3.1 ± 0.7

F I G U R E 2
Improvement in neck esthetic appearance (upper panel-side/ profile view, lower panel-front view) as observed 3 months following the last treatment (right) compared to baseline (left).F I G U R E 3 Reduced forehead wrinkles as observed 3 months after the last treatment (right) compared to baseline (left).F I G U R E 4 Reduced periorbital and facial wrinkles as observed 3 months after the last treatment (right) compared to baseline (left).

F I G U R E 5
Reduced periorbital wrinkles and fine lines as observed 3 months after the last treatment (right) compared to baseline (left).F I G U R E 6 Reduced facial wrinkles and fine lines as observed 3 months after the last treatment (right) compared to baseline (left).F I G U R E 7 (A) VAS scores in face and neck treatments.(B) Decrease in VAS scores during the treatment.*p < 0.05 for the difference between the first and third treatment sessions in the face and neck areas. of the neck and face in skin types II-IV female.Pain levels were low and decreased with each treatment session.Most women were satisfied with the treatment and reported they would recommend it to their friends or family.Moreover, the high safety profile of this device has been already demonstrated in a previously published in-vivo study. 18As shown in Figure 8, taken from this previously published in-vivo study, acute immediate effect was observed following application of the 1570 nm laser, showing the foci of thermal necrosis with no ablation.Streaming of nuclei in the epidermis were found, with condensation of collagen and pyknosis of cells of capillary walls in the dermis, and the surrounding skin appeared within normal range.Small remnants of thermal necrosis were observed in foci, and mild granulocyte infiltration was detected in the area 3 days after irradiation.Mild leukocyte infiltration with fibroblast proliferation was detected, and regeneration found to be complete 7 days after irradiation.No crusts were found, and multinucleated giant cells and proliferating fibroblasts were seen near lesions 2 weeks after irradiation.This observation of the natural wound healing process supports the phenomenon shown in our study, indicating that the 1570 non-ablative fractional laser is associated with a low rate of adverse effects and may be applicable for almost every patient.