Evolution of the Picosecond Laser: A Review of Literature

Safety and efficacy of a picosecond 755-nm alexandrite laser combined with topical tranexamic acid in the treatment of melasma

BACKGROUND

The picosecond 755-nm alexandrite laser and topical tranexamic acid (TA) have shown promise in treating melasma.

AIM

This aim of this study was to evaluate the efficacy and safety of combining to a picosecond 755-nm alexandrite laser combined with topical TA for melasma treatment.

PATIENTS AND METHODS

Forty-eight patients' facial halves with bilateral symmetrical melasma were randomized to receive either topical TA and picosecond laser treatment or laser monotherapy. All patients received three consecutive picosecond laser treatment sessions at 4-week intervals, and additional one side facial received topical TA treatment twice daily until 4 weeks after the third treatments. Efficacy was assessed using the Modified Melasma Area and Severity Index (mMASI) score, VISIA (Canfield, USA) red area feature counts, and average pore volume as measured by Antera 3D®. Patient satisfaction was evaluated through questionnaires.

RESULTS

Thirty-five patients completed the study. Post-treatment, mMASI scores and VISIA red area feature counts were lower in combination therapy halves and laser monotherapy halves, and average melanin level was lower in the combination therapy halves (p < 0.05). Comparisons between the combination therapy halves and laser monotherapy halves after the third treatment revealed significant differences in mMASI scores, melanin levels, and VISIA red area feature counts (p < 0.05). After treatment, patient satisfaction rates in the combination therapy halves and monotherapy halves was 71.4% and 54.3%, respectively (p < 0.05). No obvious adverse effects were observed in the combination therapy halves; whereas, 10.42% (5/48) of participants in the laser monotherapy halves experienced temporary pigmentation, which resolved within 3 months.

CONCLUSION

The picosecond 755-nm alexandrite laser, when used independently and in combination with topical TA, has been proven to be effective in the improvement of melasma. However, the combined treatment approach showed a more pronounced improvement in melasma symptoms, with higher patient satisfaction, and was associated with a lower incidence of adverse effects. These findings strongly support that integrating topical TA with picosecond laser therapy as a superior therapeutic strategy for melasma management.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry: ChiCTR2200057771.

Modulation of Photosensitizing Responses in Cell Culture Environments by Different Medium Components

Many cell culture experiments are performed under light to evaluate the photodynamic or photosensitizing efficacy of various agents. In this study, the modulation of photosensitizing responses and phototoxicity under cell culture conditions by different medium components was investigated. The significant levels of reactive oxygen species (ROS) generated from DMEM, RPMI 1640, and MEM were observed under the irradiation of fluorescent light (FL) and white and blue LEDs, indicating that these media have their own photosensitizing properties; DMEM showed the most potent property. Phenol red-free DMEM (Pf-D) exhibited a stronger photosensitizing property than normal DMEM by 1.31 and 1.25 times under FL and blue LEDs, respectively; phenol red and riboflavin-free DMEM (PRbf-D) did not show any photosensitizing properties. The inhibitory effect on light transmission was more pronounced in DMEM than in RPMI, and the interference effect on green LED light was greatest at 57.8 and 27.4%, respectively; the effect disappeared in Pf-D. The media containing riboflavin induced strong phototoxicity in HaCaT keratinocytes by generating H2O2 under light irradiation, which was quenched by sodium pyruvate in the media. The presence of serum in the media was also reduced the phototoxicity; H2O2 levels in the media decreased serum content dependently. The phototoxicity of erythrosine B and protoporphyrin IX under FL was more sensitively pronounced in PRbf-D than in DMEM. The present results indicate that several medium components, including riboflavin, phenol red, sodium pyruvate, and serum, could modulate photosensitizing responses in a cell culture system by inducing photosensitizing activation and by interfering with irradiation efficacy and ROS generation.

In Vivo Evaluation of Laser-Induced Optical Breakdown (LIOBS) by 1064-nm Nd:YAG Fractional Picosecond Laser With Reflectance Confocal Microscopy and Precise Histopathologic Correlation

OBJECTIVES

Picosecond lasers with a microlens array can cause laser-induced optical breakdown (LIOBS) and LIC (Intradermal laser-induced cavitation) within high-fluence areas. This study aimed to describe the clinical, reflectance confocal microscopy (RCM), histopathological findings, and the characteristics of vacuoles caused by LIOBS and LIC in individuals with skin types III and IV.

MATERIALS AND METHODS

This study was performed on six Chilean healthy volunteers, males and females, aged 35-65 years old with Fitzpatrick skin phototypes III-IV. The laser was applied in the inner proximal area of the nondominant arm. RCM evaluation was performed 24 h later; 48 h later, skin biopsies were performed on the laser-treated areas. Clinical, histological, and RCM findings were recorded.

RESULTS

Every individual developed a 10 mm2 area of clinical erythema in the treated area. Under RCM, all six volunteers had hyporeflective spherical structures at the level of the epidermis, consistent with intraepidermal vacuoles. Histopathological evaluation revealed different sizes of vacuoles in both the epidermis and dermis.

CONCLUSION

The LIOBS and LIC processes and the secondary production of vacuoles could be highly valuable for effective dermal remodeling treatment and aid in promoting the production of new collagen, elastic fibers, and growth factors that could improve skin texture. These structures were visible under RCM and histopathological evaluation.

Skin rejuvenation through topical application of indocyanine green with diffractive optical element mode of 785 nm picosecond laser in Asian females

BACKGROUND

Indocyanine green (ICG) exhibits robust absorption near 800 nm.

AIMS

To examine the clinical effects of combining ICG with a 785 nm picosecond laser for treating photo-aged skin.

PATIENT/METHODS

A 785 nm 600 picosecond laser was used on the facial area of 16 female patients with Fitzpatrick skin type III and IV (mean age: 58.44 ± 5.24 years) after applying 0.0125% ICG cream. A total of 3000 shots were administered in diffractive optical element mode at a pulse energy of 200 mJ and frequency of 10 Hz. Hyperpigmented lesions were treated using the Zoom handpiece set at a spot size of 3-4 mm, pulse energy of 60-120 mJ, and frequency of 3-7 Hz. Patients underwent five sessions of treatment at intervals of 1-2 weeks. Wrinkles, pores and pigmented lesions were assessed at the initial assessment and 4 weeks after the final treatment using the Modified Fitzpatrick Wrinkle Scale and 10-point visual analog scale, respectively. Skin biopsy of the postauricular area was performed on two consenting patients.

RESULTS

Significant improvements in wrinkles (p = 0.02), pores (p = 0.034), and hyperpigmentation (p = 0.036) were observed, along with increased patient subjective improvement. Adverse effects were transient and well-tolerated. Hematoxylin and eosin and Masson's trichrome staining revealed increased and thickened dermal collagen fibers. Immunohistochemical staining revealed increased expression of collagen I and III throughout the papillary and upper reticular dermis, along with diffuse increase of STRO-1 in the dermis.

CONCLUSIONS

The combined application of a 785 nm picosecond laser and ICG yielded promising clinical outcomes for treating photo-aged skin in Asian patients with Fitzpatrick skin type III and IV.

Assessing the efficacy of a 100 ps Nd:YAG laser for tattoo removal in a minipig model

Using a minipig model, we evaluated the efficacy of the 100 ps Nd:YAG laser in the removal of tattoo pigments, specifically blue, green, red, and yellow. We observed distinct pigment responses to 532/1064 nm wavelengths at various energy settings. Through a combination of clinical, spectroscopic, and histological methods, we found the 532 nm wavelength to be most effective in disrupting all colors, with notable results for green and yellow at 0.4 J/cm2 and red at 0.72 J/cm2. The 1064 nm wavelength reduced pigment in yellow (1.51 J/cm2), green (1.35 J/cm2), and blue (1.11 J/cm2) tattoos, but was surpassed by the 532 nm in efficiency. Our data underscores the crucial interplay between pigment traits and laser settings in tattoo removal. We advocate for tailored treatment strategies, integrating pigment hue and laser wavelength, to enhance removal outcomes.

755-nm picosecond laser plus topical 20% azelaic acid compared to topical 20% azelaic acid alone for the treatment of melasma: a randomized, split-face and controlled trial

PURPOSE

Melasma remains a refractory skin condition that needs to be actively explored. Azelaic acid has been used for decades as a topical agent to improve melasma through multiple mechanisms, however, there is a lack of research on its combination with laser therapy. This study evaluated the effectiveness of isolated treatment with topical 20% azelaic acid and its combination with 755-nm picosecond laser in facial melasma patients.

METHODS

A randomized, evaluator-blinded, controlled study was conducted on 30 subjects with facial melasma in a single center from October 2021 to April 2022. All subjects received topical 20% azelaic acid cream (AA) for 24 weeks, and after 4 weeks, a hemiface was randomly assigned to receive 755-nm picosecond (PS) laser therapy once every 4 weeks for 3 treatments. Treatment efficacy was determined by mMASI score evaluations, dermoscopic assessment, reflectance confocal microscopy (RCM) assessments and patient's satisfaction assessments (PSA).

RESULTS

Treatment with 20% azelaic acid, with or without picosecond laser therapy, significantly reduced the hemi-mMASI score (P < 0.0001) and resulted in higher patient satisfaction. Improvements in dermoscopic and RCM assessments were observed in both sides of the face over time, with no difference between the two sides. RCM exhibited better dentritic cell improvement in the combined treatment side. No patients had serious adverse effects at the end of treatment or during the follow-up period.

CONCLUSION

The additional use of picosecond laser therapy showed no clinical difference except for subtle differences detected by RCM assessments.The study was registered in the Chinese Clinical Trial Registry (ChiCTR2100051294; 18 September 2021).

The efficacy and safety of low- versus high-fluence fractional picosecond Nd:YAG 1064-nm laser in the treatment of acne scars: A randomized split-face comparison study

BACKGROUND

Differences in clinical efficacy based on the fluence of fractional picosecond laser treatment for acne scars are unknown.

OBJECTIVE

To compare the efficacy and safety of low-fluence versus high-fluence fractional picosecond Nd:YAG 1064-nm laser treatment in acne scar patients.

METHODS

In this 12-week, investigator-blinded, randomized, split-face study, 25 patients with moderate-to-severe acne scars received three sessions of high-fluence laser treatment (1.0 J/cm2 ) on one side of their face and low-fluence (0.3 J/cm2 ) on the other side every 4 weeks. Patients were assessed using acne scar counts, the scar global assessment (SGA), and the ECCA scar grading scale every 4 weeks. The histological analysis compared the acne scars obtained before and 4 weeks after treatment.

RESULTS

At their last visit, 88.00% and 92.00% of the subjects achieved >30% reduction in scar counts on the low- and high-fluence sides, respectively, without a significant difference between the two sides. On both sides, the scar counts, SGA, and ECCA score significantly improved 4 weeks after the last treatment. Although the high-fluence side showed a greater reduction in scar counts (-66.73%) than the low-fluence side (-62.13%), the two sides had no significant difference in the grading scores. The high-fluence side showed significantly more severe pain and higher side-effect scores immediately and 4 weeks after treatment. Histological analysis revealed a significantly increased collagen, elastin, and vimentin expression after treatment on the low-fluence side.

CONCLUSIONS

The low-fluence setting demonstrated comparable efficacy and superior safety in treating acne scars compared with the high-fluence setting.

Evaluation of Wrinkle and Dermal Thickness in the Forearm before and after Picosecond Laser Therapy

Background

Skin wrinkles are generated as a result of the aging process. Dermal thickness underneath a wrinkle decreases absolutely. Approximately 20% of dermal thickness disappears as people become elderly. In recent times, people have attempted to reduce wrinkles using various procedures. Currently, available picosecond lasers in dermatology can create mechanical stress and the energy can be fractionated via diffractive lens arrays (DLA). An emerging indication for the picosecond laser includes photorejuvenation. Non-ablative laser skin rejuvenation therapy demonstrates the dermis can be safely reconstructed by only irradiating the skin surface with a laser. The clinical effects of picosecond pulse laser have been frequently reported, but few studies have included histological investigation.

Aims and Objectives

This study aimed to evaluate wrinkle and dermal thickness in the forearm before and after picosecond laser therapy.

Materials and Methods

Twenty healthy male and female subjects between 36 and 55 years old with wrinkles in the forearm who met the sample requirements and were willing to participate were recruited in this study. Clinical examination and biopsy for histopathological examination were carried out before and 4 weeks after therapy, then treatment was carried out using a picosecond laser.

Results

At 1-month follow-up, a significant improvement was noted in wrinkle and dermal thickness (P < 0.05).

Conclusions

This picosecond 755 nm alexandrite laser with DLA was found to be very effective in treating wrinkles, which was confirmed by a dermatologic assessment from forearm photographic assessment scaled and dermal thickness improvement.

Comparison of 1064-nm Nd:YAG picosecond laser using fractional micro-lens array vs. ablative fractional 2940-nm Er:YAG laser for the treatment of atrophic acne scar in Asians: a 20-week prospective, randomized, split-face, controlled pilot study

Background

The 1064-nm Nd:YAG picosecond lasers using fractional micro-lens array (P-MLA) was a promising therapy for skin resurfacing. However, no studies have compared P-MLA with ablative fractional 2940-nm Er:YAG lasers (AF-Er) in the treatment of atrophic acne scars.

Objectives

To evaluate the efficacy and safety of P-MLA and AF-Er for the treatment of atrophic acne scars.

Methods

We performed a prospective, randomized, split-face, controlled pilot study. Thirty-one Asian patients with mild to moderate atrophic acne scars underwent four consecutive sessions of randomized split-face treatment with P-MLA and AF-Fr at 4-week intervals. The efficacy of the two devices were evaluated by Echelle d'Evaluation Clinique des Cicatrices d'acne (ECCA) grading scale, Investigator's Global Assessment (IGA) score and patient's satisfaction. VISIA analysis was also performed to evaluate the pore and skin texture. Adverse events were recorded at each follow-up.

Results

The P-MLA afforded comparable clinical responses in scar appearance as AF-Er based on the investigator's assessments (ECCA percent reduction: 39.11% vs. 43.73%; IGA score: 2.97 ± 0.65 vs. 3.16 ± 0.68; P > 0.05 for both). However, the result of patient satisfaction indicated the AF-Er-treated side achieved a slightly greater improvement in scar appearance (3.97 ± 0.78 vs. 3.55 ± 0.71; P < 0.05). Overall, the two devices did not differ largely in terms of efficacy. VISIA analysis revealed similar changing patterns of the pore and skin texture between two devices. For safety profiles, no serious side effects were reported on both sides. The P-MLA showed lower pain level, shortened duration of crust shed and edema, and less occurrence of PIH (P < 0.05 for all).

Conclusion

Compared with AF-Er, P-MLA afforded comparable effect and more safety profiles in treating atrophic acne scars in Asian patients.

Clinical trial registration

ClinicalTrials.gov, identifier NCT05686603.

Response predictor for pigment reduction after one session of photo-based therapy using convolutional neural network: A proof of concept study

BACKGROUND

Identifying treatment responders after a single session of photo-based procedure for hyperpigmentary disorders may be difficult.

OBJECTIVES

We aim to train a convolutional neural network (CNN) to test the hypothesis that there exist discernible features in pretreatment photographs for identifying favorable responses after photo-based treatments for facial hyperpigmentation and develop a clinically applicable algorithm to predict treatment outcome.

METHODS

Two hundred and sixty-four sets of pretreatment photographs of subjects receiving photo-based treatment for esthetic enhancement were obtained using the VISIA® skin analysis system. Preprocessing was done by masking the facial features of the photographs. Each set of photographs consists of five types of images. Five independently trained CNNs based on the Resnet50 backbone were developed based on these images and the results of these CNNs were combined to obtain the final result.

RESULTS

The developed CNN algorithm has a prediction accuracy approaching 78.5% with area under the receiver operating characteristic curve being 0.839.

CONCLUSION

The treatment efficacy of photo-based therapies on facial skin pigmentation can be predicted based on pretreatment images.

Comparison of the efficacy and safety of a 730 nm picosecond titanium sapphire laser and a 755 nm picosecond alexandrite laser for the treatment of freckles in Asian patients: A two-center randomized, split-face, controlled trial

OBJECTIVE

The 730 nm picosecond titanium sapphire laser is a novel laser that shows promising results in treating freckles. This study aimed to further investigate the efficacy and safety of the 730 nm picosecond titanium sapphire laser for treating freckles in Asian patients compared with those of the 755 nm picosecond alexandrite laser.

METHODS

Each face of 86 participants was split into two parts and randomly assigned either one session of 730 or 755 nm picosecond-laser treatment each. Efficacy and safety were determined based on blinded visual evaluations and self-reports at each follow-up visit.

RESULTS

The treatment outcomes of the 730 nm picosecond laser for the treatment of freckles were comparable to those of the 755 nm picosecond laser, with 68.99 ± 7.42% and 69.27 ± 7.75% clearance, respectively (p > 0.05). Participants achieved similar Global Aesthetic Improvement Scale scores (4.04 ± 0.31 vs. 4.02 ± 0.30, respectively [p > 0.05]). Additionally, the 730 nm picosecond laser was perceived to be less painful than the 755 nm picosecond laser (4.69 ± 1.63 vs. 5.65 ± 1.80 nm, p < 0.0001).

CONCLUSION

The 730 nm picosecond laser is safe and effective for the treatment of freckles in Asian patients. Besides, the 730 nm picosecond laser is less painful than the 755 nm picosecond laser.

Comprehensive examination of tattoo removal using a 150 ps Nd:YAG laser in a porcine model

This study aimed to investigate the efficacy of a Nd:YAG laser with a pulse duration of 150 ps at different laser parameters. The effects on multiple-colored tattoos with such ultrashort pulses has not been previously described in the literature. In vivo experiments were conducted on porcine skin to analyze the fragmentation efficiency of five different tattoo colors using different wavelengths, pulse energies, and spot sizes. The results showed that the optimal tattoo clearance to safety ratio for blue, green, red, and yellow tattoos with a 532 nm wavelength was 0.96-2.39 J/cm2. The laser with a wavelength of 1064 nm demonstrated the highest efficacy in eliminating black tattoos, with positive results observed for green and blue pigments at a fluence of 3.02 J/cm2. The study provides valuable insights into the efficacy of laser treatment with 150 ps for removing tattoos of different colors using different laser parameters. This information can help dermatologists and practitioners perform more efficient and effective tattoo removal with fewer side effects.

Melanin-dependent tissue interactions induced by a 755-nm picosecond-domain laser: complementary visualization by optical imaging and histology

Fractional picosecond-domain lasers (PSL) induce optical breakdown, which correlates histologically to vacuolization in the epidermis and dermis. In this ex vivo porcine study, we sought to establish a framework for the investigation of laser-tissue interactions and their dependence on melanin density. Light- (melanin index: 24.5 [0-100]), medium- (58.7), and dark-pigmented (> 98) porcine skin samples were exposed to a 755-nm fractional PSL and examined with dermoscopy, line-field confocal optical coherence tomography (LC-OCT), conventional OCT, and subsequently biopsied for digitally stained ex vivo confocal microscopy (EVCM) and histology, using hematoxylin and eosin (HE) and Warthin-Starry (WS) melanin staining. Dermoscopy showed focal whitening in medium- and dark-pigmented skin. Similarly, LC-OCT and OCT visualized melanin-dependent differences in PSL-induced tissue alterations. Vacuoles were located superficially in the epidermis in dark-pigmented skin but at or below the dermal-epidermal junction in medium-pigmented skin; in light-pigmented skin, no vacuoles were observed. Histology confirmed the presence of vacuoles surrounded by areas void of WS staining and disrupted stratum corneum in darker skin. The combined use of optical imaging for multiplanar visualization and histological techniques for examination of all skin layers may mitigate the effect of common artifacts and attain a nuanced understanding of melanin-dependent laser-tissue interactions.

A Pilot Split-Neck Case Study to Compare the Efficacy of the Long-Pulsed 755 nm Laser and the 532 nm Picosecond Laser for Acrochordon Removal

Cutaneous papillomas or acrochorda usually appear after the 4th decade of life in areas with skin folds. Conventional methods of removal are associated with bleeding problems, pain and prolonged sequelae. Thus, acrochorda removal with lasers has gained attention. In this study, we compared the efficacy of two popular laser types with different wavelengths and pulse widths for removal of skin tags. A 60-year-old Korean male noticed skin tags on his neck bilaterally. All tags were treated in a single session, on one side with a picosecond (ps)-domain 532 nm Nd:YAG laser and on the contralateral side with a long-pulsed (LP) 755 nm alexandrite laser. The endpoint for the ps-532 laser was immediate whitening, while that for the LP and quasi-LP (QLP) 755 lasers were visible changes on the surface of the lesion. Antibiotic ointment was applied, dressing was done and clinical photographs were taken. Both lasers effectively removed the skin tags at all settings in a single session without bleeding and with minimal discomfort. Crust formation occurred on both sides with natural shedding within 1 to 2 weeks. Transient erythema lasted longer in the tags treated with the ps-532 laser. At the 5th month of follow-up, residual lesions were detected on the field treated with the ps-532 laser. No persistent side effects such as scarring or postinflammatory hyperpigmentation (PIH) were observed. In conclusion, both the ps-532 nm Nd:YAG and the 755 nm alexandrite lasers ensured safe and effective removal of skin tags in a single session without adverse sequelae.

Efficacy and Safety of Extracellular Matrix on Wound Healing After Picosecond Laser Therapy

BACKGROUND

Extracellular matrix (ECM), a material with tissue repair function, is applied to treat various wounds. However, the role of ECM in facilitating wound healing after facial laser treatment remains elusive.

OBJECTIVE

To assess the efficacy and safety of ECM in promoting wound healing after picosecond laser therapy (PLT).

MATERIALS AND METHODS

Eighteen female subjects with benign pigmentation disorders were randomly assigned to the ECM (n = 9) and control groups (n = 9). After PLT, the ECM and control groups were treated with ECM and facial moisturizer in the first 7 days, respectively. The severity of erythema and edema was assessed using photographs. The duration of erythema, edema, scab shedding, postinflammatory hyperpigmentation incidence (PIH), and adverse events was documented in detail.

RESULTS

Compared with the control group, the ECM group had a shorter duration of erythema, edema, and scab shedding after PLT (p < .01). A significantly decreased severity of erythema (p < .05) and edema (p < .01) was found in the ECM group versus the control group, respectively. The PIH incidence in the ECM group was lower than in controls, albeit without statistical significance. No serious adverse events were observed during the follow-up.

CONCLUSION

Extracellular matrix is an effective and safe dressing for promoting wound healing after PLT.

Video education improves patients' knowledge and satisfaction in treatment of solar lentigines with picosecond 755-nm alexandrite laser: A retrospective study

Background

Picosecond lasers are widely used in dermatologic and cosmetic practice. In clinical practice, informed consent for laser treatments is critical to ensure patients' understanding of health information.

Objectives

To evaluate whether video-based informed consent improves patient comprehension and satisfaction.

Methods

The study was performed from August 1 to November 30, 2022. Solar lentigines patients who fulfilled the inclusion criteria were included. Before October 1, 2022, traditional informed consent methods were performed. In the subsequent 2 months, a video-based informed consent was used as an adjunct to traditional consenting methods. Finally, patient comprehension of relevant knowledge about laser treatment and client satisfaction were assessed.

Results

A total of 106 patients were included. The mean number of correct answers in the comprehension assessment in the video-based informed consent group was significantly higher than that in the traditional informed consent group (4.4 ± 1.2 vs. 3.4 ± 1.1, p < 0.001). Compared to the traditional informed consent group, more correct answers in the video-based informed consent group were provided by older patients (3.9 ± 1.2 vs. 2.9 ± 1.1, p = 0.004) and patients with lower education levels (4.1 ± 1.1 vs. 3.0 ± 1.2, p < 0.001). The mean satisfaction score in the video-based informed consent group was significantly higher than that in the traditional informed consent (27.8 ± 5.7 vs. 24.3 ± 6.2, p = 0.003).

Conclusion

Video-based informed consent helps patients learn clinical literacy more effectively and improves patient satisfaction, especially in those with lower education levels and older ages.

Microlesion healing dynamics in in vivo porcine skin after treatment with 1064 nm picosecond-domain Nd:YAG laser

The fractionated picosecond laser produces microscopic lesions in the epidermis and dermis due to laser-induced optical breakdown (LIOB). There have been multiple histological reports, but the present literature lacks detailed in vivo studies after treatment with high-power laser systems. Our study aimed to characterize the healing patterns of microlesions induced with 150 ps duration 1064 nm MLA-type picosecond laser. The induced picosecond laser-tissue reactions with pulse energy of 50-250 mJ and different treatment modes were observed in in vivo porcine skin model over 10 days after the laser procedure. A macroscopic evaluation was combined with microscopic histological analysis to observe the healing dynamics of laser-induced microlesions. Superficial, intraepidermal cavitation bubbles were induced using microbeam fluence of 4-20 J/cm² . Skin irritation scores positively correlated with pulse energy and dose. Our findings demonstrate that dose and pulse energy had a direct impact on epidermal thickness and lesions healing dynamics.

Truncal Acne and Scarring: A Comprehensive Review of Current Medical and Cosmetic Approaches to Treatment and Patient Management

Acne vulgaris is one of the most common skin disorders worldwide. It typically affects skin areas with a high density of sebaceous glands such as the face, upper arms, chest, and/or back. Historically, the majority of research efforts have focused on facial acne vulgaris, even though approximately half of patients with facial lesions demonstrate truncal involvement. Truncal acne vulgaris is challenging to treat and poses a significant psychosocial burden on patients. Despite these characteristics, studies specifically examining truncal acne vulgaris are limited, with treatment guidelines largely derived from facial protocols. Therefore, truncal acne remains an understudied clinical problem. Here, we provide a clinically focused review on the epidemiology, evaluation, and available treatment options for truncal acne vulgaris. In doing so, we highlight knowledge gaps with the goal of spurring further investigation into the management of truncal acne vulgaris.

Morphologic and molecular biologic analyses of the skin rejuvenation effect of the fractional 1064-nm picosecond laser: An animal study

OBJECTIVES

Application of the picosecond laser in the field of dermatology has expanded from tattoo removal to skin rejuvenation on a clinical basis. Although various mechanisms of pigment removal have been elucidated, the molecular changes associated with skin rejuvenation have yet to be identified. The aim of this study was to explore the theoretical basis and to evaluate the efficacy of skin rejuvenation using a 1064-nm fractional picosecond laser in a mouse model.

METHODS

We conducted an in vivo study using a fractional picosecond laser on the skin of old and young female hairless mice and performed topographical, histological, micro-, and electron microscopic assessments.

RESULTS

The topography of the skin surface was enhanced and showed increased dermal thickness on histological examination. Electron microscopy revealed disarranged collagen bundles with microspaces and vascular leakage in the upper dermis. Levels of collagen synthesis markers and various inflammatory cytokines, such as procollagens, interleukin-1β, tumor necrosis factor-α, and heat shock proteins, were elevated in the laser-treated skin.

CONCLUSIONS

This study provides a possible mechanism for the skin rejuvenation effect of fractional picosecond laser that has been reported previously in clinical observations. Based on our findings, the fractional picosecond laser could be widely applied in clinical settings where dermal regeneration and promotion of skin rejuvenation is required.

Direct and Indirect Roles of Men in Determining Women Decision to Use Laser Procedures for Skin Care

Laser procedures for skin care is becoming increasingly popular and used by the global community and affect many aspects of human life. However, there is very little research on the role of men in women's decision to follow this dermatological procedure. This study aimed to identify the role of men in motivating women to choose laser-based procedure. A systematic literature review research design was applied in this study. A total of 27 papers were obtained by searching PubMed Central for the 2013-2022 editions. The extraction of samples and the motivation of patients or research respondents in choosing laser procedures for cosmetic treatments were conducted to obtain clues about the role of men in making these decisions. Only six studies explicitly reveal the role of men as motivators of women to perform laser-based dermatological procedures. Four of these six studies were conducted in Asia in countries with a high degree of collectivism. The remaining two studies reveal a minor role for men in women's motivation to choose dermatological procedures. Other studies only indirectly implicate the role of men through intrasexual competition, increased self-esteem, and the needs of the world of work. Limitations of the study lies in the non-specificity of the study sample in the female population, laser-based treatments, and the role of men in motivating women. The role of men in motivating women to perform laser-based skin care procedures is stated explicitly in collectivist cultures while only implicitly in individualist cultures. These findings indicate that the strategy of utilizing the added value of men to laser treatment procedures should be directed at the relationship between men and women in real terms in collective cultured countries.

Treatment of facial pigmented disorders with a 785-nm picosecond Ti:sapphire laser in Asians: A report of three cases

Since the advent of the theory of selective photothermolysis, the importance of targeting the chromophore and minimizing the surrounding damage has been extensively discussed. Picosecond-domain laser (ps-laser) treatment with a wide range of wavelengths is an emerging option for various pigmented lesions; however, no definitive treatment choice has been confirmed. The authors aimed to investigate the efficacy and safety of a ps-laser with a 785-nm wavelength for the treatment of facial pigmented lesions in Asians. Three Korean patients with facial pigmented lesions were recruited for the study. A 785-nm ps-laser with a fractionated and an unfractionated handpiece was utilized to administer the treatment. The clinical outcome was evaluated by a clinician by comparing pre- and post-treatment photographs. All patients exhibited a significant improvement in pigmented lesions including freckles, lentigines, and melasma, after three to four sessions of treatment. No adverse events, including post-inflammatory hyperpigmentation or hypopigmentation were observed. In conclusion, this novel 785-nm Ti:sapphire ps-laser may be an effective and safe modality for treating pigmented lesions in skin of color.

Effects of water cooling on laser‐induced thermal damage in rat hepatectomy

Purpose

High‐powered lasers are commonly used for tissue resection in surgeries, including liver resection, medically known as hepatectomy; however, such lasers inevitably induce thermal damage that causes postoperative complications. This study aims to explore the effects of water cooling and different laser output modes on laser‐induced thermal damage during hepatectomy.

Methods

To avoid the influence of superposition, a 980‐nm diode laser was used for a single‐point hepatectomy. Eighteen Sprague–Dawley rats were used to explore the effects of water cooling and different laser output modes. A constant energy 10‐J laser was used to cut the liver tissue with a power of 10 W and time of 1 second. The rats were randomly divided into six groups. The first three groups were assigned as test subjects for different laser output modes. Group 1 was operated with a continuous laser output for a duration of 1 second. Groups 2 and 3 were operated with a pulsed laser output for a duration of 1 second and a pulse width of 0.5 and 0.25 seconds, respectively. Groups 4, 5, and 6 were assigned for the water cooling test. Water cooling was performed based on the parameters of the first three groups. Medical saline (0.9% NaCl) was used for water cooling. The main observation indicators were resection efficiency and thermal damage, including the area of the thermal damage zone. Resection efficiency is calculated by dividing the resection area by the total thermal damage area.

Results

In the three water cooling groups, the area of the resection, carbonized, sub‐boiling coagulated, and total thermal damage zones were 0.0677, 0.00, 1.7293, and 2.2982 mm² in Group 4; 0.0465, 0.00, 1.3205, and 1.8414 mm² in Group 5; and 0.0565, 0.00, 1.4301, and 1.9650 mm² in Group 6, respectively. Compared with the first three groups, the water cooling groups exhibited significantly reduced thermal damage areas of in the carbonized, sub‐boiling coagulated, and total thermal damage zones (p < 0.001 for all). In addition, there was no statistical difference in the resection area, vacuolated area, and resection efficiency. Furthermore, there was no statistical difference in the area of each thermal damage zone between the continuous and pulsed output groups. The resection efficiencies were 4.82%, 3.34%, 3.73%, 3.93%, 3.36%, and 3.01% in Groups 1 to 6, respectively. Moreover, there was no statistical difference (p > 0.05) in the resection efficiencies.

Conclusion

Water cooling can reduce the total laser‐induced thermal damage area and prevent tissue carbonization. Therefore, this cooling method can be used as a simple and safe strategy for controlling thermal damage during hepatectomy.

Evaluation of the efficacy and safety of the 1064 nm picosecond Nd:YAG laser with a topically applied gold and diamond suspension for facial skin rejuvenation: a pilot study

To investigate the efficacy and safety of combined treatment with a serum comprising a micro-diamond suspension and micro-gold cage with a 1064 nm picosecond neodymium-doped yttrium aluminum garnet (Nd:YAG) laser for facial skin rejuvenation. Topical serum was applied to the entire face and allowed to penetrate the skin and hair follicles for 20 min. Each participant was then treated with a 1064 nm picosecond Nd:YAG laser on the face. Photographs of each participant were taken at baseline, immediately after treatment, and 2 weeks after treatment using an imaging tool (Mark-Vu®; PSI PLUS, Suwon, Republic of Korea). Global improvement scores by two blinded investigators and participants' satisfaction scores were also assessed. The melanin index (MI), transepidermal water loss (TEWL), and skin hydration were evaluated using a device. Parameters associated with skin rejuvenation were assessed using Mark-Vu®. Adverse events were observed and reported by participants and physicians during the treatment and follow-up visit. At week 2, 40% (4/10) of the participants showed more than moderate clinical improvement in the investigator's global improvement assessment. No significant differences were observed in the MI, TEWL, skin hydration level, or skin parameters of Mark-Vu®. At week 2, 40% of the participants reported a high satisfaction score and minimal side effects. The novel topical facial serum comprising micro-diamond suspension and micro-gold cage is safe and effective when combined with laser treatment for facial rejuvenation. This article is protected by copyright. All rights reserved.

Efficacy of a laser with a pulse duration of 300 ps in skin rejuvenation and treatment of pigmentation disorders in Asians: a series of four cases

The photothermal effect of lasers is minimized and the photoacoustic effect is maximized as the pulse duration is shortened. Therefore, picosecond lasers with a short pulse and high peak power can be used to effectively treat various pigment disorders by reducing tissue damage. The first picosecond lasers were used for tattoo removal; they are also widely used for pigment treatment because of their reduced side effects compared with nanosecond lasers. Recently, picosecond lasers have been shown to be effective in the treatment of various skin conditions such as acne scars and large pores. There are many studies on picosecond lasers; however, there are no studies on a laser with a pulse duration of 300 ps. This report describes the use of a 300 ps Nd:YAG laser for treating pigment disorders and for skin rejuvenation in four Asians, with no side effects. Determining the clinical significance of the 300 ps pulse duration through comparative studies with various picosecond lasers is needed.

A single-blinded, randomized, controlled trial comparing efficacy between low-fluence alexandrite 755-nm picosecond laser and low-fluence neodymium-doped yttrium aluminum garnet (Nd:YAG) 1064-nm picosecond laser for the treatment of ultraviolet B-induced hyperpigmentation

BACKGROUND

Hyperpigmentation is a common concern of patients in dermatology clinics. Although there are many treatment options, lasers are considered a promising therapy for various hyperpigmentary conditions.

OBJECTIVES

This study aims to evaluate the efficacy of alexandrite 755-nm picosecond and neodymium-doped yttrium aluminum garnet (Nd:YAG) 1064-nm picosecond lasers for the treatment of ultraviolet B (UVB)-induced hyperpigmentation in Asians.

MATERIALS AND METHODS

A randomized, single-blinded study was conducted. UVB-induced hyperpigmentation was performed in three spots by narrowband UVB. After 2 weeks, these three spots were allocated into 755-treated, 1064-treated, and control sites. Patients received weekly laser treatments for five sessions. Follow-ups were scheduled at 1 and 2 months after the last session.

RESULTS

Twenty patients attended the study. Overall, 755-nm and 1064-nm picosecond lasers showed a significant improvement in the mean lightness index (L*) compared to the control site, which started at Day 49 and Day 77, respectively. The mean L* of the 755-nm-treated site was also higher than that of the 1064-nm-treated site at Day 105 (p ≤ 0.001). Initially, the mean L*, physician's visual analog scale (VAS), and patient satisfaction with the 1064-nm picosecond laser were better than those with the 755-nm picosecond laser. Nevertheless, an inversion of the mean L* and VAS was noted at Day 49, whereas the mean patient satisfaction was noted at Day 77. In the subgroup analysis, a 755-nm picosecond laser effectively treated Fitzpatrick skin types (FPTs) III and IV. However, the mean L* of the 1064-nm picosecond laser was not significantly different from that of the control for FPT4.

CONCLUSION

The alexandrite 755-nm picosecond and Nd:YAG 1064-nm picosecond lasers appear to be effective and safe modalities for treating UVB-induced hyperpigmentation. With the setting employed in this study, the outcome after the 755-nm picosecond laser treatment seemed superior to that of the 1064-nm picosecond laser treatment, especially for FPT4.

Laser-Assisted Drug Delivery of Tranexamic Acid by Picosecond Laser in Postinflammatory Hyperpigmentation: A Split-Area Double Blind Randomized Prospective Study

Background: Tranexamic acid has been reported to benefit the treatment of postinflammatory hyperpigmentation (PIH). Laser-assisted drug delivery (LADD) could facilitate the efficacy of topically applied drugs into the dermis. This split-area randomized prospective study aims to assess whether early utilization of the LADD procedure with tranexamic acid delivery followed by picosecond lasers can attenuate the PIH better than the utilization of picosecond lasers alone. Patients and methods: Ten post-traumatic cases of PIH in 10 patients (8 female and 2 male) with an average age of 34.2 ± 11.2 years were included in this clinical trial. Using block randomization to determine the treatment side, one side of each area of the PIH was separated from the midline into two halves belonging to the control and tranexamic acid groups. The half area of the tranexamic acid group was further topically applied with 10% tranexamic acid solution. This procedure was repeated every 6 weeks, four times in total. Results: The self-assessment of the hyperpigmentation and overall satisfaction of the treatment outcome were not significantly different between the treatment and control sides. Conclusions: This split-area study revealed that, compared with picosecond alone, there was no significant difference adopting tranexamic acid in LADD after nonablative fractional picosecond laser for PIH.

Treatment of nevus of Ota with 1064 nm picosecond Nd:YAG laser: A retrospective study

Nevus of Ota has been successfully treated by lasers. Currently, 1064 nm picosecond Nd:YAG lasers have become available for the treatment of pigmented disorders. However, there are few studies concerning the application of 1064 nm picosecond Nd:YAG laser in nevus of Ota. This study aimed to evaluate the efficacy and safety of a 1064 nm picosecond Nd:YAG laser for the treatment of nevus of Ota. We conducted a retrospective analysis of Chinese patients with nevus of Ota who had been treated with a 1064 nm picosecond Nd:YAG laser. Those who had any other laser treatment during the period of picosecond laser treatment were excluded. Via a visual analog scale for percentage of pigmentary clearance in standard photographs, the treatment efficacy was assessed by three blinded physician evaluators. A total of 16 subjects were included in this retrospective study. The average age at the beginning of treatment was 16.87 years old (range of 4 months to 59 years), and all patients were of Fitzpatrick skin type IV. Total treatment ranged from 1 to 5 sessions. A 1064 nm picosecond Nd:YAG laser with a mean fluence of 1.8-4.3 J/cm² was used at 3-12 month intervals. The mean efficacy score for all 16 patients was 2.56 after one session, and the mean efficacy score of 13 patients who completed two sessions and nine patients who completed three sessions were 3.15 and 3.51, respectively. Postinflammatory hyperpigmentation after treatment was only observed in 1 (1/16, 6.25%) patient. The 1064 nm picosecond Nd:YAG laser is an effective and safe approach for treating nevus of Ota.

Effective Picosecond Nd:YAG laser on seborrheic dermatitis and its mechanism

BACKGROUND

The Picosecond Nd:YAG laser has advantages in skin rejuvenation, which has little damage to surrounding tissues due to the ultra-short pulse width. We perform clinical application of Picosecond Nd:YAG laser's tender skin mode, which could improve the seborrheic dermatitis.

MATERIALS AND METHODS

Sixty-three subjects with facial seborrheic dermatitis are randomized to be control and observation groups. Records regarding skin subjective improvement, skin barrier function-related data, skin microbial status, and dermoscopy detection of the two patient groups before and after treatments are investigated.

RESULTS

Improvements of erythema and scales in observation group are significant compared with controls (p < 0.05). In terms of skin barrier function, there are significant changes regarding transepidermal water loss and epidermal seborrhea content in observation group after the laser treatments. Skin microbial state, pityrosporum furfur, and Demodex significantly decrement in observation group. Microscopical findings of infiltration mode advise that scales and capillary congestion and dilatation are significantly improved in observation group. Compared with controls, epidermal gloss increases, pore fineness improves, and capillary density decreases in the observation group.

CONCLUSIONS

Picosecond Nd:YAG laser could efficiently decrease erythema area and seborrheic dermatitis scales and reduce pruritus incidence. The sebaceous gland secretion of seborrhea and multiplying of epidermal parasitic microbiological are inhibited after laser treatment. Less epidermal seborrhea content and inflammation are induced by parasitic microbiology, which is helpful for skin barrier function and microvascular remodeling.

Efficacy of 1064-nm Nd:YAG picosecond laser in lichen amyloidosis treatment: clinical and dermoscopic evaluation

Lichen amyloidosis (LA) is a type of primary localized cutaneous amyloidosis characterized by multiple localized, hyperpigmented, grouped papules, in which the deposition of amyloid materials from altered keratinocytes usually resists to current treatments. We presented two LA patients with non-satisfactory results of topical treatments. After the first treatment using 1064-nm Nd: YAG picosecond (ps-Nd:YAG) laser, there was an improvement with persistence up to 3-month follow up after five sessions of 4-week interval, as well as a decrease in number, thickness, and darkness of lesions from clinical and dermoscopic evaluation. Thus, the ps-Nd:YAG laser could be efficacious for LA treatment.

Visible light. Part I: Properties and cutaneous effects of visible light

Approximately 50% of the sunlight reaching the Earth's surface is visible light (400-700 nm). Other sources of visible light include lasers, light-emitting diodes, and flash lamps. Photons from visible light are absorbed by photoreceptive chromophores (e.g., melanin, heme, and opsins), altering skin function by activating and imparting energy to chromophores. Additionally, visible light can penetrate the full thickness of the skin and induce pigmentation and erythema. Clinically, lasers and light devices are used to treat skin conditions by utilizing specific wavelengths and treatment parameters. Red and blue light from light-emitting diodes and intense pulsed light have been studied as antimicrobial and anti-inflammatory treatments for acne. Pulsed dye lasers are used to treat vascular lesions in adults and infants. Further research is necessary to determine the functional significance of visible light on skin health without confounding the influence of ultraviolet and infrared wavelengths.

Comparison of 1064-nm and Dual-Wavelength (532/1064-nm) Picosecond-Domain Nd:YAG Lasers in the Treatment of Facial Photoaging: A Randomized Controlled Split-Face Study

BACKGROUND AND OBJECTIVES

To compare the efficacy and safety of 1064-nm and dual-wavelength (532/1064 nm) picosecond Nd:YAG lasers with a holographic optic in the treatment of facial photoaging.

STUDY DESIGN/MATERIALS AND METHODS

In this prospective, randomized split-face study, each half of each participant's face was randomly treated with a 1064-nm or 532/1064-nm picosecond laser. All participants underwent five treatment sessions and follow-up visits 1 and 3 months after the final treatment. The primary outcomes were measured as the global photoaging scores, determined by two physicians who were blinded to the treatments. The secondary outcomes were the participant-assessed Global Aesthetic Improvement Scale (GAIS) and satisfaction scores. Histopathological examinations were performed.

RESULTS

Global photoaging scores decreased significantly after treatment with either laser. The global photoaging scores, GAIS scores, and satisfaction scores did not differ significantly between the 1064-nm and 532/1064-nm picosecond laser treatments. Histological changes were similar between the two groups. Intraepidermal vacuoles and dermal hemorrhaging were observed immediately and 24 h after treatment. After five treatments, neocollagenesis was observed in the upper dermis of both groups, and elastic fibers were more elongated and orderly.

CONCLUSIONS

Treatments with 1064-nm and 532/1064-nm picosecond Nd:YAG lasers were comparably effective at improving photodamaged facial skin by remodeling the collagen and elastin network through laser-induced optical degradation and vascular damage.

Treatment of pigmentary disorders using picosecond laser in Asian patients: A meta-analysis and systematic review

There were many studies evaluating the effect of picosecond (PS) lasers, but no meta-analysis examined the effects of PS laser in the treatment of pigmentary disorders in Asians. The aim of this article was to review the before-after effect of PS laser in Asians for the treatment of pigmentary disorders. PubMed, Embase, and Cochrane library were searched for articles published up to May 2020. The evaluations were summarized into a 4-point scale that ranged from <25% (poor), 25%-50% (fair), 50%-75% (good), and 75%-100% (excellent). Effect sizes (ESs) were calculated according to laser wavelengths and lesion types. There were two randomized controlled trials, three single-arm trials, and three case series, with 200 patients. At 3 months after treatment, of all included patients, 3% (95%CI: 1%-6%) were evaluated as poor or worse, 9% (95%CI: 2%-21%) as fair, 29% (95%CI: 12%-50%) as good, and 56% (95%CI: 28%-83%) as excellent. The 532 and 1064, and 755 nm PS lasers had similar ESs across all four response groups. This meta-analysis suggested that 56% of Asian patients who underwent PS laser for the treatment of pigmentary disorders were evaluated as "excellent" about the pigment clearance by a dermatologist at least 3 months after treatment.

Dermatologic Laser Side Effects and Complications: Prevention and Management

The evolution of modern laser and light-based systems has mirrored the demand for clinically effective treatments and the need for safer technologies with reduced postoperative recovery, side effects, and complications. With each new generation of lasers, more selective tissue destruction can be achieved with reduced unwanted sequelae. Patient selection and preparation, operator technique, and expeditious recognition and management of post-treatment side effects are paramount in avoiding complications and patient dissatisfaction. An overview of important variables to consider for dermatologic laser treatments are presented in order to provide a framework to reduce the severity and duration of possible post-treatment side effects and complications.

Comparative Effectiveness of 755-nm Picosecond Laser, 755- and 532-nm Nanosecond Lasers for Treatment of Café-au-Lait Macules (CALMs): A Randomized, Split-Lesion Clinical Trial

BACKGROUND AND OBJECTIVES

Many types of lasers have been used to treat café-au-lait macules (CALMs) since the introduction of the selective photothermolysis theory. However, the efficacy and safety of picosecond lasers, compared with those of nanosecond lasers, have not been researched. To compare the efficacy and safety of 755 nm picosecond laser (PS-755 nm), Q-switched (QS) Alexandrite 755 nm nanosecond laser (QS-755 nm), and QS Nd:YAG 532 nm nanosecond laser (QS-532 nm) for treating CALMs.

STUDY DESIGN/MATERIALS AND METHODS

Forty-one patients received several treatments at 3-month intervals. Lesions were divided into two or three approximately equal parts, which were randomly treated with PS-755 nm, QS-755 nm, and QS-532 nm. The safety and efficacy of three lasers were determined based on blinded visual assessments and self-reports of patients three months after the comparative trial.

RESULTS

Visual assessment 3 months after the comparative trial revealed that there was no statistically significant difference among the sites treated by QS-755 nm (2.84 ± 1.11), QS-532 nm (2.63 ± 1.06), and PS-755 nm (2.74 ± 1.05) lasers. Five (26.32%) of 19 patients showed lesion recurrence. Adverse effects included acneiform miliaris, hypopigmentation, and hyperpigmentation, which were resolved within 12 months. Five (26.32%) of 19 patients who showed lesion recurrence 1-5 months after laser treatment had lightened or cleared at least 50% of the lesion. 46.67% of patients were satisfied or very satisfied with the outcome of the overall treatment.

CONCLUSIONS

PS-755 nm, QS-755 nm, and QS-532 nm laser treatments were equally effective in treating and improving CALMs. PS-755 nm caused fewer adverse effects. Individuals can react differently to different types of lasers. Patch tests should be conducted before the treatment. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Comparison of a 1064-nm neodymium-doped yttrium aluminum garnet picosecond laser using a diffractive optical element vs. a nonablative 1550-nm erbium-glass laser for the treatment of facial acne scarring in Asian patients: a 17-week prospective, randomized, split-face, controlled trial

BACKGROUND

Novel picosecond lasers using a diffractive optical element (P-DOE) have been available for skin resurfacing with distinct mechanisms. However, there are limited data directly comparing P-DOE and conventional fractional lasers for the treatment of atrophic acne scarring.

OBJECTIVES

We sought to compare the efficacy and safety of a 1064-nm neodymium-doped yttrium aluminium garnet P-DOE and a non-ablative fractional laser (NAFL) in the treatment of acne scarring.

METHODS

A prospective, randomized, split-face, controlled trial was performed. One randomly assigned half-side of each patient's face (n = 25) was treated with four consecutive sessions of P-DOE at 3-week intervals and the other side with NAFL, with subsequent follow-up for 8 weeks after the final sessions. The efficacy and safety of the two lasers were determined by the Echelle d'Evaluation Clinique des Cicatrices d'acné (Scale of Clinical Evaluation of Acne Scars; ECCA) grading scale, Investigator's Global Assessment (IGA) score and patients' reports at the final visit. Histologic analysis was also performed.

RESULTS

The P-DOE-treated side achieved a significantly better improvement in acne appearance (ECCA per cent reduction: 55% vs. 42%) with less severe pain (4.3 vs. 5.6) (P < 0.05). The IGA score and subjective satisfaction were consistent with ECCA score results. Occurrences of treatment-related side-effects were also lower in the group treated with P-DOE (P < 0.05). Histologic analysis revealed elongation and increased density of neocollagen fibres, elastic fibres and mucin throughout the dermis from both sides.

CONCLUSIONS

Compared with NAFL, P-DOE afforded better clinical outcomes and fewer side-effects in the treatment of acne scarring in Asian patients.