Med Lasers 2023; 12(2): 116-121  https://doi.org/10.25289/ML.23.018
Utility of the stacking method for depressed scar improvement using a 1,064-nm, microlens array, picosecond-dominant laser in Republic of Korea: retrospective clinical study
Yeong Jin Kim, Han Gyu Cha, Eun Soo Park
Department of Plastic and Reconstructive Surgery, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Republic of Korea
Correspondence to: Eun Soo Park
E-mail: peunsoo@schmc.ac.kr
ORCID: https://orcid.org/0000-0003-2966-9122
Received: May 30, 2023; Accepted: June 5, 2023; Published online: June 30, 2023.
© Korean Society for Laser Medicine and Surgery. All rights reserved.

This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Background: The depression type of scars is the most complex problem that a plastic surgeon confronts. Traditionally, many plastic surgeons use the subcision technique for sunken scars to release scar tissue. The mechanism of the subcision technique involves cutting the contracted collagen beneath the pitted scar. The laser-induced optical breakdown effect induced by a fractional picosecond laser could produce vacuoles under the depressed scars in the epidermal and dermal layers, which is similar to the mechanism of subcision. This study investigated the efficacy and safety of a 1,064-nm fractional picosecond laser treatment for depressed scars using a stacking method.
Methods: The patients’ medical charts and procedure records were reviewed retrospectively to evaluate the outcomes and complications after the procedures. The patients were treated with a 1,064-nm fractional picosecond laser at 4-week intervals with a spot size of 3 mm, fluence of 1.5 to 5.5 J/cm2, and frequency of 10 Hz with a combination of microlens arrays.
Results: Fifteen and sixteen patients were male and female, respectively. The mean modified Vancouver Scar Scale for the treated scars was 7.75 ± 1.07 points before treatment, which decreased to 4.66 ± 0.87 points one month after the final treatment. The mean patients’ satisfaction scores were 2.11 ± 0.52 before treatment and 4.20 ± 0.72 one month after picosecond laser treatment.
Conclusion: The stacking method can cause cavitation at the deep dermis, and cavitation stimulates collagen and elastic fibers. As cavitation is formed, the recovery period is shortened, and the effects of depressed scar treatment are very satisfactory.
Keywords: Lasers; Stacking method; Depressed scar
INTRODUCTION

The depression type of scar is the most complex problem confronting plastic surgeon. Depressed scars commonly occur as a result of acne and posttraumatic injuries. These depressed scars can persist for a long time and are difficult to conceal with makeup, causing a lot of discomfort [1]. Traditionally, many physicians used subcision technique at depressed scars to release the scar tissue. The mechanism of subcision technique is by cutting contracted collagen and fibromuscular attachments beneath the pitted scar. Other treatment options include ablative or nonablative laser skin resurfacing, chemical peeling, microdermal abrasion, punch elevation, punch graft, subcision, filler injection, and dermal rolling [2]. However, there is still no perfect consensus on treatment, and research is still ongoing. Recently, there have been publications on the use of picosecond laser therapy to complement the limitations of subcision and effectively treat depressed scars [3]. Laser-induced optical breakdown (LIOB) effect induced by fractional picosecond laser could make lots of vacuoles under the depressed scars in epidermal and dermal layer, which is similar to the mechanism of subcision. In addition, based on the evidence that we can extend the influence of laser treatment to the deep dermis by stacking pulses of picosecond laser, we have designed a study to investigate the efficacy and safety of a 1,064-nm fractional picosecond laser treatment for depressed scars by stacking method.

METHODS
Ethics statement: This study was approved by the Institutional Review Board (IRB) of Soonchunhyang University Bucheon Hospital (IRB no. 2023-05-023-003) and all procedures were carried out in accordance with the guidelines of the Helsinki Declaration. Informed consent was obtained from the participants.

Patients

Of patients who underwent depressed scar treatment using stacking method of picosecond laser treatment between December 2020 and January 2023 were enrolled in this study. Patients’ medical charts were reviewed retrospectively to evaluate outcomes and complications before and after the picosecond laser treatment. Patients with matured scars were included. All of patients had no significant familial or medical history. Patients who had undergone previous scar laser treatments or surgical interventions were excluded from the study.

Picosecond laser treatment

All patients were applied a topical 5% lidocaine anesthetic ointment (Emla®; AstraZeneca AB) in the target area for laser treatment. After 30 minutes to 1 hour of application, patients washed off the ointment with mild soap and water immediately before the laser session. The patients were received 1,064-nm fractional picosecond laser (Picocare Majesty®; WONTECH) at a 4-week interval with a spot size of 3 mm, fluence of 1.5 to 5.5 J/cm2, and frequency of 10 Hz in combination of microlens array (MLA). The laser was stacked on the same spot until pinpoint bleeding occurred. We educated all patients to avoid direct sunlight and recommended to apply a sunscreen agent between the laser treatment sessions for minimizing post-inflammatory hyperpigmentation. Photographic findings were taken before and after the each session of laser treatment.

Evaluation of outcomes

One month after the treatment was completed, clinical photographs of the patients were taken. The patients were asked to rate their satisfaction with the improvements in the aesthetic appearance and depressed of the scars on a scale of 5-point (1, very unsatisfied; 2, unsatisfied; 3, adequate; 4, satisfied; 5, very satisfied). In addition, a plastic surgeon who did not participate in the treatment evaluated the improvement of the patients’ scars using clinical photographs before the initial treatment and one month after the final treatment based on the modified Vancouver Scar Scale (Table 1).

Table 1 . Modified Vancouver Scar Scale

Vascularity
Normal0
Pink1
Red2
Purple3
Pigmentation
Normal0
Hypopigmentation1
Hyperpigmentation2
Pliability
Normal0
Supple1
Yielding2
Firm3
Ropes4
Contracture5
Depression (mm)
Flat0
<11
1-22
2-33
>34


Statistical analysis

Statistical analysis were performed using IBM SPSS version 20.0 (IBM Corp.). Wilcoxon signed rank test was used to compare the modified Vancouver Scar Scale and the patient’s satisfaction scores before and after the picosecond laser treatment. The results were expressed as the mean ± standard deviation. In all analysis, p-value of less than 0.05 was taken to indicate statistical significance.

RESULTS

Participant characteristics

There were 15 male and 16 female with an mean age of 39.3 years, and the study subjects ranged in age from 5 to 80 years old. The leading cause of scars was trauma, accounting for 67.7%, followed by previous operation at 25.8%, and the patients were received 3 to 8 sessions of picosecond laser (Table 2).

Table 2 . Demographic data

CharacteristicValue (n = 31)
Sex
Male15 (48.4)
Female16 (51.6)
Age (yr)39.3 (5-80)
Cause
Postoperative scar8 (25.8)
Trauma21 (67.7)
Burn1 (3.2)
Acne1 (3.2)
Session4.6 (3-8)

Values are presented as number (%) or mean (range).



The end point outcomes

The mean modified Vancouver Scar Scale for the treated scars was 7.75 ± 1.07 points before treatment, and it decreased to 4.66 ± 0.87 points one month after final treatment. There was a statistically significant difference between before and after laser treatment (p < 0.05). All values of modified Vancouver Scar Scale showed improvement after the laser treatment (Fig. 1). In particular, the score for the focused depression scar decreased from 1.61 ± 0.39 points before the treatment to 0.9 ± 0.26 points after the treatment (p < 0.05). The mean patients’ satisfaction scores were 2.11 ± 0.52 before treatment. It increased to 4.20 ± 0.72 one month after picosecond laser treatment (Fig. 2). This result was statistically significant (p < 0.05).

Figure 1. The mean modified Vancouver Scar Scale for the treated scars was 7.75 ± 1.07 points before treatment, and it decreased to 4.66 ± 0.87 points one month after final treatment. There were statistically significant different between before and after laser treatment (p < 0.05).

Figure 2. The mean patients’ satisfaction scores were 2.11 ± 0.52 before treatment. It increased to 4.20 ± 0.72 one month after picosecond laser treatment. This result was statistically significant (p < 0.05).
DISCUSSION

Since its initial U.S. Food and Drug Administration (FDA) approval for tattoo removal in 2012, picosecond laser has been extensively researched and utilized for various other applications [4]. Plastic surgeons have applied picosecond laser to treat a wide range of skin problems, including wrinkles and acne scars, leading to numerous studies on its effectiveness and safety [5]. In 2014, it received FDA approval for the treatment of wrinkles and acne scars, and has been in use ever since. Our center’s preliminary research has also revealed positive effects on pigmented scars [6].

The main mechanism of picosecond laser lies in LIOB, which leads to the regeneration of collagen and soft tissue, resulting in therapeutic effects. The concept of LIOB involves the absorption of laser energy by melanocytes in the epidermis, which triggers the seeding of free electrons. However, seeding occurs within the focal point of the laser beam where the intensity is high. The current maximum power density (irradiance) of the picosecond laser in use is insufficient to reach the threshold power density required for LIOB in the dermal tissue. Therefore, a fractional lens has been introduced to generate LIOB in the dermal tissue. There are two types of tips for a picosecond laser; diffractive optical element (DOE) and MLA. DOE effectively distributes a single beam into multiple branches through a special lens, allowing for uniform irradiation. It is particularly effective for phototherapy and skin rejuvenation, providing short treatment times and minimal discomfort. On the other hand, by using a MLA, the laser beam is divided into multiple branches and focused to provide strong irradiation to the tissue, achieving a robust effect even with the same output. Therefore, through the use of MLA, energy can be absorbed and free electrons can be seeded. Once a sufficient number of free electrons are seeded, avalanche ionization occurs, leading to a rapid increase in the production of free electrons. These free electrons then form a plasma cloud that absorbs the remaining laser energy and undergoes explosive expansion. This process generates a shock wave, and as it concludes, a vacuole is formed in the tissue due to plasma ablation. Additionally, nearby blood vessels undergo dilation, initiating an inflammatory response that includes the activation of fibroblasts. Through this process, cavitation is formed in both the epidermis and dermis. This cavitation influences the regeneration of collagen, elastic tissue, and mucin, and picosecond laser aids in releasing contracted collagen fiber strands [7,8].

The depression type of scar is the most complex problem confronting plastic surgeon. Depressed scars are characterized by a sunken appearance compared to the surrounding skin, resulting from damage to collagen, fat, or other tissues beneath the skin. These scars can be caused by factors such as acne, trauma, or previous surgical procedures. Currently, there is no universally established treatment method for addressing these scars. Traditionally, subcision technique was used at depressed scars to release the scar tissue. The subcision technique, an invasive method, involves breaking the fibrotic strands that connect the scar to the underlying tissue [9]. Also, when the scar beneath the skin is precisely cut, new connective tissue regenerates in the defect with collagen regeneration [10].

Laser-induced optical break down effect induced by fractional picosecond laser could make lots of vacuoles under the depressed scars in epidermal and dermal layer, which is similar to the mechanism of subcision. Furthermore, the use of lasers can compensate for the drawbacks of subcision, such as the potential for damage to surrounding nerves, blood vessels, and muscles. Previous studies have showed that picosecond laser is a safe and effective method for treating traumatic wound scars with depression [3]. However, this study had limitations in terms of the lack of histological research. In other studies, histologically, the formation of vacuoles with picosecond laser treatment was demonstrated [11]. In this study, it was found that lower energy levels could create vacuoles more deeply. Additionally, the utilization of the stacking method allowed for the potential impact on the mid to deep dermis. Therefore, due to the generation of vacuoles over a wider area, the effects of subcision are enhanced, leading to greater improvement in depressed scars through collagen regeneration and achieving skin rejuvenation. In our study, we observed significant improvement in depression as well as in other factors on the mean modified Vancouver Scar Scale. Our patients showed dramatic color improvement and elevation of depressed scar after stacking method of fractional picosecond laser treatment with MLA tip (Figs. 3, 4). By removing and releasing fibrous strand beneath the depressed scar like subcision technique, fractional picosecond laser could prompt scar elevation and promote collagen remodeling phase in the target area, resulting more aesthetic results in patients’ satisfaction score. However, this study had a limitation regarding the lack of histological evidence to determine whether collagen regeneration occurs after cavitation formation. Therefore, further histological research is necessary in the future.

Figure 3. A 33-year-old female patient was treated for depressed scar on the right nasolabial fold that occurred after surgery. The depression of the scar was severe during the initial treatment (A), and it showed further improvement during the second session (B). One month after the final treatment (5th sessions), significant improvement in the depression was observed in the photographs (C).

Figure 4. A 61-year-old male who was treated for a scar on his nose that occurred after trauma. The depression of the scar was severe during the initial treatment (A), and it showed further improvement during the third session (B). One month after the final treatment (5th sessions), significant improvement in the pigmentation and depression was observed in the photographs (C).

In conclusion, stacking method can make cavitation at deep dermis and cavitation stimulates collagen and elastic fibers. As cavitation is formed, the recovery period is shortened and the effects of depressed scar treatment are very satisfactory.

ACKNOWLEDGMENTS

None.

AUTHOR CONTRIBUTIONS

Conceptualization: ESP. Data curation: YJK. Formal analysis: YJK. Investigation: HGC. Methodology: YJK. Project administration: ESP. Software: HGC. Validation: YJK. Visualization: YJK. Writing–original draft: YJK. Writing–review & editing: all authors.

CONFLICT OF INTEREST

Eun Soo Park is an editorial board member of the journal, but was not involved in the review process of this manuscript. Otherwise, there is no conflict of interest to declare.

FUNDING

None.

DATA AVAILABILITY

Contact the corresponding author for data availability.

SUPPLEMENTARY MATERIALS

None.

References
  1. Hazarika N, Archana M. The psychosocial impact of acne vulgaris. Indian J Dermatol 2016;61:515-20.
    Pubmed KoreaMed CrossRef
  2. Lipper GM, Perez M. Nonablative acne scar reduction after a series of treatments with a short-pulsed 1,064-nm neodymium:YAG laser. Dermatol Surg 2006;32:998-1006.
    Pubmed CrossRef
  3. Ahn KH, Park ES, Choi CY. Effectiveness of a fractional picosecond 1,064-nm laser in improving traumatic scars with depression. Med Lasers 2020;9:179-83.
    CrossRef
  4. Torbeck RL, Schilling L, Khorasani H, Dover JS, Arndt KA, Saedi N. Evolution of the picosecond laser: a review of literature. Dermatol Surg 2019;45:183-94.
    Pubmed CrossRef
  5. Brauer JA, Kazlouskaya V, Alabdulrazzaq H, Bae YS, Bernstein LJ, Anolik R, et al. Use of a picosecond pulse duration laser with specialized optic for treatment of facial acne scarring. JAMA Dermatol 2015;151:278-84.
    Pubmed CrossRef
  6. Ahn KH, Park ES, Nam SM. Usefulness of a 1,064 nm microlens array-type, picosecond-dominant laser for pigmented scars with improvement of Vancouver Scar Scale. Med Lasers 2019;8:19-23.
    CrossRef
  7. Choi Y, Park ES. Subsurface fractional ablative resurfacing of a periareolar scar using 1,064-nm picosecond laser with micro-lens array. Arch Aesthet Plast Surg 2018;24:36-8.
    CrossRef
  8. Tanghetti EA. The histology of skin treated with a picosecond alexandrite laser and a fractional lens array. Lasers Surg Med 2016;48:646-52.
    Pubmed CrossRef
  9. Spangler AS. New treatment for pitted scars; preliminary report. AMA Arch Derm 1957;76:708-11.
    Pubmed CrossRef
  10. Orentreich DS, Orentreich N. Subcutaneous incisionless (subcision) surgery for the correction of depressed scars and wrinkles. Dermatol Surg 1995;21:543-9.
    Pubmed CrossRef
  11. Lyu H, Park J, Lee HC, Lee SJ, Kim YK, Cho SB. In vivo and ex vivo skin reactions after multiple pulses of 1,064-nm, microlens array-type, picosecond laser treatment. Med Lasers 2020;9:142-9.
    CrossRef


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