A comparative study with a 755 nm picosecond Alexandrite laser with a diffractive lens array and a 532 nm/1064 nm Nd:YAG with a holographic optic

Ultrasound-assisted laser therapy for selective removal of melanoma cells

The current study explores the potential of ultrasound-assisted laser therapy (USaLT) to selectively destroy melanoma cells. The technology was tested on an ex vivo melanoma model, which was established by growing melanoma cells in chicken breast tissue. Ultrasound-only and laser-only treatments were used as control groups. USaLT was able to effectively destroy melanoma cells and selectively remove 66.41% of melanoma cells in the ex vivo tumor model when an ultrasound peak negative pressure of 2 MPa was concurrently applied with a laser fluence of 28 mJ/cm2 at 532 nm optical wavelength for 5 min. The therapeutic efficiency was further improved with the use of a higher laser fluence, and the treatment depth was improved to 3.5 mm with the use of 1,064 nm laser light at a fluence of 150 mJ/cm2. None of the laser-only and ultrasound-only treatments were able to remove any melanoma cells. The treatment outcome was validated with histological analyses and photoacoustic imaging. This study opens the possibility of USaLT for melanoma that is currently treated by laser therapy, but at a much lower laser fluence level, hence improving the safety potential of laser therapy.

Optical Effects of Focused Fractional Nanosecond 1064-nm Nd:YAG Laser: Techniques of Application on Human Skin

BACKGROUND AND OBJECTIVES

Considering the pulse widths of picosecond and nanosecond lasers used in cutaneous laser surgery differ by approximately one order of magnitude, can nanosecond lasers produce the optical effect in human skin similar to laser-induced optical breakdown (LIOB) caused by picosecond lasers?

METHODS

Cutaneous changes induced by a focused fractional nanosecond 1064-nm Nd:YAG laser were evaluated by VISIA-CR imaging, histological examination, and harmonic generation microscopy (HGM).

RESULTS

A focused fractional nanosecond 1064-nm Nd:YAG laser can generate epidermal vacuoles or dermal cavities similar to the phenomenon of LIOB produced by picosecond lasers. The location and extent of photodisruption can be controlled by the laser fluence and focus depth. Moreover, laser-induced shock wave propagation and thermal degeneration of papillary collagen can be observed by HGM imaging.

CONCLUSION

Focused fractional nanosecond lasers can produce an optical effect on human skin similar to LIOB caused by picosecond lasers. With techniques of application, the treatment can induce epidermal and dermal repair mechanisms in a tunable fashion to improve skin texture, wrinkles, scars, and dyspigmentation, without disrupting the epidermal surface.

Picosecond alexandrite laser treatment of nevus of Ota in children

BACKGROUND

The picosecond alexandrite laser has been safely and effectively used to treat the nevus of Ota in adults. However, limited data are available for children.

OBJECTIVE

To investigate the efficacy, safety, and correlative influencing factors of a 755nm picosecond alexandrite laser in the treatment of nevus of Ota in children.

METHODS

We retrospectively analyzed Chinese children with nevus of Ota who received a 755nm picosecond alexandrite laser treatment in a tertiary dermatological hospital.

RESULT

A total of 305 pediatric patients received an average of two treatments achieving an average of 79% pigment clearance. After the first treatment, 22 patients achieved complete clearance (95%-100%), and 72 patients achieved excellent response (75%-94%), with an average initial efficacy of 63% lesion clearance. Treatment at an early age achieved better initial efficacy (0- to 12-month group >1- to 6-year group, 6- to 12-year group). And 0- to 12-month group achieved better final efficacy. More treatment sessions also increased the final efficacy. Both initial efficacy and final efficacy were better when treating a darker lesion. The incidence of complications was 12.1%, with 10.8% being post-inflammatory hyperpigmentation and 1.3% being hypopigmentation. The rate of recurrence was 6.6%.

LIMITATION

Retrospective study.

CONCLUSION

A 755nm picosecond alexandrite laser is safe and effective in treating nevus of Ota in children. Younger to initiate treatment, darker lesions, and more treatments are positively associated with better pigmentation clearance.

Fractional picosecond laser treatment of non-acne atrophic scars and scar erythema in Chinese patients

BACKGROUND

Fractional picosecond lasers (FPL) are reported to be effective and safe for atrophic acne scars and post-acne erythema. However, there is no evidence regarding the effectiveness and safety of FPL treatment for non-acne atrophic scars and scar erythema among Chinese patients.

METHODS

In this retrospective study, 12 Chinese patients with non-acne atrophic scars, including nine with scar erythema, were treated with one to three sessions of 1064 nm FPL treatment. Clinical improvement was objectively assessed through blinded evaluations by external physicians. A modified Manchester Scar Scale (mMSS) and the Clinician Erythema Assessment Scale (CEAS) were individually used to evaluate atrophic scars and scar erythema based on photographs. Physician-assessed and subject-assessed Global Aesthetic Improvement Scale (GAIS) were used to assess changes before and after FPL treatment. Patient satisfaction and adverse events were also documented.

RESULTS

Total mMSS scores, as well as three parameters (color, distortion, and texture), were significantly decreased after FPL treatment, with a mean reduction of 3.18 ± 1.60 in total scores (p < 0.05). The CEAS scores were significantly reduced from 2.41 ± 0.98 before treatment to 0.41 ± 0.40 at the final visit (p < 0.05). Based on physician-assessed and subject-assessed GAIS scores, 11 (91.7%) patients were improved after FPL treatment. 33.3% of patients were very satisfied, and 41.7% were satisfied. No serious, prolonged (> 3 weeks) adverse events were observed.

CONCLUSION

Our study suggests that 1064 nm FPL treatment may be a promising option for non-acne atrophic scars, especially with scar erythema. Further studies are needed to confirm our results.

Comparison of the fractionated Nd: YAG 1064-nm picosecond laser with holographic optics and the fractional CO2 laser in atrophic acne scar treatment: a prospective, randomized, split-face study

KEY POINT

The 1064-nm picosecond laser with holographic optics demonstrated significant efficacy in treating atrophic acne scars.

BACKGROUND

Picosecond lasers with fractionated optics have enabled the development of a breakthrough skin rejuvenation method. The authors compared the fractionated, non-ablative neodymium-doped yttrium aluminum garnet 1064-nm picosecond laser with holographic optics and the fractional CO2 laser in treating atrophic acne scars.

METHODS

One side of each patient's face was randomly allocated and treated with three sessions of the 1064-nm picosecond laser with holographic optics at 2-month intervals. In contrast, the other side was treated with the fractional CO2 laser. Participants were followed up 3 months after the final session. The primary outcome included the physicians' evaluation using the ECCA grading scale and a four-point scale to assess improvement. The patients' assessment of progress, their overall satisfaction and preferences, and the side effects were also evaluated.

RESULTS

No significant difference was observed between the two lasers in terms of the mean ECCA scores after treatments (P = 0.209). The physicians' improvement assessment was more significant for the fractional CO2 laser (P = 0.001). The patients' evaluation of improvement and subjective satisfaction were consistent with physicians' four-point scale results. The picosecond laser side had fewer adverse effects (P < 0.001).

CONCLUSION

The fractionated, non-ablative Nd: YAG 1064-nm picosecond laser with holographic optics and the fractional CO2 laser were effective and safe in treating atrophic acne scars. Significantly better clinical outcomes were observed with the fractional CO2 laser, whereas fewer adverse effects were noted with the 1064-nm picosecond laser with holographic optics.

Comparison of the 1064-nm picosecond laser with fractionated microlens array and 1565-nm non-ablative fractional laser for the treatment of enlarged pores: a randomized, split-face, controlled trial

PURPOSE

This split-face randomized study compared the efficacy and safety between 1064-nm picosecond laser with fractionated microlens array (MLA) and 1565-nm nonablative fractional laser to treat enlarged pores.

METHODS

Participants with enlarged facial pores were enrolled and underwent three consecutive sessions at 2-week intervals with either a 1064-nm picosecond laser with MLA or a 1565-nm nonablative fractional laser. Images were captured at each visit. Objective (pore number) and subjective assessments, including patient self-evaluations and quartile improvement scales, were used to evaluate the treatment efficacy. The pain levels and adverse effects were recorded at each subsequent visit.

RESULTS

The participants were 3 men and 22 women with enlarged facial pores. At the initial and 2-month checkups after the last treatment, the pore numbers were significantly decreased bilaterally for both lasers. The respective quartile improvement scale scores for the 1064-nm picosecond and 1565-nm fractional lasers were 2.22 ± 1.06 and 2.14 ± 1.11, while those for patient self-assessment were 3.72 ± 0.74 and 3.68 ± 0.75. The pore number, quartile improvement scale score, and patients' self-assessments did not differ significantly between the two lasers. Treatment with the 1064-nm picosecond laser better reduced pain compared with the 1565-nm nonablative fractional laser (4.11 ± 1.33 vs. 4.83 ± 1.17). The occurrence of pigmentation did not differ significantly between the lasers.

CONCLUSION

Both the 1064-nm picosecond laser with MLA and the 1565-nm nonablative fractional laser are viable options for treating enlarged pores, and showed comparable respective efficacies; however, the former was less likely to cause hyperpigmentation and was better tolerated.

Picosecond lasers in cosmetic dermatology: where are we now? An overview of types and indications

Q-switched lasers have undeniably revolutionized the field of laser dermatology since four decades ago. Just as the first-generation laser emits its photonic signal in a few nanoseconds, the picosecond laser delivers pulse widths of at least ten times shorter. These devices offer a powerful tool for treating a wide range of skin conditions with a minimal downtime for visible improvement. For the current study, a literature research was performed on the dermatological applications of picosecond laser. The literature searched on this topic between 1999 and 2023 accessible through various platforms produce a result of 62 articles. The included studies have discussed the application of picosecond laser technology in tattoo removal, treatment of epidermal and dermal pigmentation, and collagen remodeling. After sifting the data from the articles into tables, the results were discussed in detail. The study shows a lot of evidence towards the efficacy of picosecond laser, yet it draws attention to its downsides.

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.

Performance evaluation of mesoscopic photoacoustic imaging

Photoacoustic mesoscopy visualises vascular architecture at high-resolution up to ~3 mm depth. Despite promise in preclinical and clinical imaging studies, with applications in oncology and dermatology, the accuracy and precision of photoacoustic mesoscopy is not well established. Here, we evaluate a commercial photoacoustic mesoscopy system for imaging vascular structures. Typical artefact types are first highlighted and limitations due to non-isotropic illumination and detection are evaluated with respect to rotation, angularity, and depth of the target. Then, using tailored phantoms and mouse models, we investigate system precision, showing coefficients of variation (COV) between repeated scans [short term (1 h): COV= 1.2%; long term (25 days): COV= 9.6%], from target repositioning (without: COV=1.2%, with: COV=4.1%), or from varying in vivo user experience (experienced: COV=15.9%, unexperienced: COV=20.2%). Our findings show robustness of the technique, but also underscore general challenges of limited-view photoacoustic systems in accurately imaging vessel-like structures, thereby guiding users when interpreting biologically-relevant information.

Laser Treatment Monitoring with Reflectance Confocal Microscopy

Laser treatments have become popular in Dermatology. In parallel to technologic development enabling the availability of different laser wavelengths, non-invasive skin imaging techniques, such as reflectance confocal microscopy (RCM), have been used to explore morphologic and qualitative skin characteristics. Specifically, RCM can be applied to cosmetically sensitive skin areas such as the face, without the need for skin biopsies. For these reasons, apart from its current use in skin cancer diagnosis, our systematic review reveals how RCM can be employed in the field of laser treatment monitoring, being particularly suitable for the evaluation of variations in epidermis and dermis, and pigmentary and vascular characteristics of the skin. This systematic review article aims to provide an overview on current applications of RCM laser treatment monitoring, while describing RCM features identified for different applications. Studies on human subjects treated with laser treatments, monitored with RCM, were included in the current systematic review. Five groups of treatments were identified and described: skin rejuvenation, scar tissue, pigmentary disorders, vascular disorders and other. Interestingly, RCM can assist treatments with lasers targeting all chromophores in the skin and exploiting laser induced optical breakdown. Treatment monitoring encompasses assessment at baseline and examination of changes after treatment, therefore revealing details in morphologic alterations underlying different skin conditions and mechanisms of actions of laser therapy, as well as objectify results after treatment.

Efficacy and safety of fractional 1064-nm picosecond laser for atrophic traumatic and surgical scars: A randomized, single-blinded, split-scar-controlled study

OBJECTIVE

A fractional 1064-nm picosecond laser is an efficient and safe treatment for atrophic acne scars. However, evidence of using a picosecond laser for atrophic posttraumatic and surgical scar therapy is lacking. This study aimed to evaluate the efficacy and safety of using a 1064-nm picosecond laser with a microlens array (MLA) for the treatment of atrophic posttraumatic and surgical scars.

METHODS

This was a prospective, intraindividual, single-blinded, randomized split-lesion-controlled trial. Twenty-five subjects with atrophic traumatic or surgical scars that existed for more than 1 year were enrolled. All atrophic scars were divided at the midline into two halves and randomly assigned to a treatment or control side. The treatment group was treated with a 1064-nm picosecond laser with an MLA handpiece (spot size: 6-8 mm, fluence: 1.0-1.2 J/cm² , repetition rate: 5 Hz, three passes) for 3 monthly sessions. The scar volumes were objectively measured using a three-dimensional (3D) photograph at baseline, 1 month after the first and second treatments, and 3 and 6 months after the final treatment. Subjective assessments were conducted by a blinded dermatologist and patients' self-assessment to evaluate improvements at 3 months after the final treatment.

RESULTS

The treated sides exhibited a significant volume reduction, with statistically significant improvements over the control group at 1 month after the first and second treatments and at 3 months after the final treatment (p = 0.024, 0.005, and 0.019, respectively). At 3 months after the final treatment, a blinded dermatologist correctly identified the treated side in 24 of 25 patients (96%). The patients rated the improvements as excellent (>75%) and marked (50%-75%) in 36% and 48% of patients, respectively.

CONCLUSION

At 3 months, the 1064-nm picosecond laser with a fractionated MLA can significantly reduce the posttraumatic and postsurgical atrophic scar volume in patients with Fitzpatrick skin types III-V. Insufficient data preclude inferences regarding efficacy at 6 months.

Characterization of picosecond laser-induced optical breakdown using harmonic generation microscopy

BACKGROUND AND OBJECTIVES

By creating microinjuries usually confined to the epidermis, a fractional picosecond 1064-nm Nd:YAG laser that delivers an array of highly focused beamlets can be effectively used for facial rejuvenation or resurfacing. However, the mechanism of dermal remodeling underlying this nonablative treatment remains unclear.

METHODS

Five participants having skin phototype III-IV were recruited for intervention using a fractional picosecond 1064-nm Nd:YAG laser system equipped with a holographic diffractive beam-splitting optic. The laser-induced histopathological changes on human skin were examined in vivo using a harmonic generation microscopy (HGM), visualizing second harmonic generation (SHG), and third harmonic generation (THG) contrasts dichromatically. SHG refers for collagen distribution, while THG represents for epidermal components in the HGM signal.

RESULTS

Histological hematoxylin and eosin staining and in vivo HGM imaging studies revealed the presence of epidermal vacuoles below the stratum granulosum along with keratinocyte degeneration or cytolysis. In addition to the epidermal vacuoles, HGM imaging exclusively demonstrated laser-induced shock wave propagation arranged as a THG-bright concentric pattern in the epidermis and loss of SHG signals in the papillary dermis immediately beneath the epidermal vacuoles.

CONCLUSIONS

Alongside generating epidermal vacuoles, the fractional picosecond 1064-nm Nd:YAG laser induced collagen changes. These collagen changes may lead to dermal remodeling and neocollagenesis underlying the fractional picosecond laser treatment.

Nonlinear absorption-based analysis of energy deposition in melanosomes for 532-nm short-pulsed laser skin treatment

BACKGROUND AND OBJECTIVES

The clinical use of 532-nm short-pulsed lasers has provided effective treatment of epidermal pigmented lesions. However, the detection of significant differences in treatment effects between picosecond and nanosecond lasers has still varied among clinical studies. For robust evaluation of the differences based on the treatment mechanism, this study presents a nonlinear absorption-based analysis of energy deposition in melanosomes for 532-nm short-pulsed laser treatment.

STUDY DESIGN/MATERIALS AND METHODS

Nonlinear absorption by melanin is modeled based on sequential two-photon absorption. Absorption cross-sections and nonradiative lifetimes of melanin, which are necessary for the nonlinear absorption-based analysis, are determined from transmittance measurement. Using the model and parameters, energy deposition in melanosomes was calculated with varying fluence and pulse width settings, including actual clinical parameters.

RESULTS

The energy deposition in melanosomes increased with shorter laser pulses, and subnanosecond laser pulses were found to be most efficient. The comparison of energy deposition calculated using clinical parameters demonstrated the differences in treatment effects between picosecond and nanosecond lasers reported in clinical studies.

CONCLUSION

The nonlinear absorption-based analysis provides quantitative evidence for the safety and efficacy evaluation of short-pulsed laser treatments, which may lead to the establishment of numerical indices for determining treatment conditions. Future studies considering the effects of the surrounding tissue on energy deposition in melanosomes will be needed.

A Randomized, Prospective, Split-Face Pilot Study to Evaluate the Safety and Efficacy of 532-nm and 1,064-nm Picosecond-Domain Neodymium:Yttrium-Aluminum-Garnet Lasers Using a Diffractive Optical Element for Non-Ablative Skin Rejuvenation: Clinical and Histological Evaluation

BACKGROUND

The advent of fractionated picosecond (ps) lasers has provided an opportunity to explore new ways of creating microinjuries in the skin to induce skin rejuvenation.

OBJECTIVE

To compare the efficacy and safety of diffractive optical element (DOE)-assisted ps neodymium: yttrium-aluminum-garnet (Nd:YAG) lasers with 532-nm and 1,064-nm wavelengths (532-nm and 1,064-nm Nd:YAG P-DOE) using a novel fractional handpiece for the treatment of photoaged skin.

METHODS

An ex vivo guinea pig skin experiment was performed by evaluating the histology of the skin after 532-nm Nd:YAG P-DOE irradiation. A randomized, prospective, split-face study was performed on eight subjects with 532-nm and 1,064-nm Nd:YAG P-DOE.

RESULTS

Based on the histological evaluation using ex vivo guinea pig skin, a reasonable safety profile and the potential to generate effective skin rejuvenation was observed using the 532-nm Nd:YAG P-DOE. Results demonstrated that both 532- and 1,064-nm Nd:YAG P-DOE were similarly effective in improving skin texture and skin pores; however, 532-nm Nd:YAG P-DOE was more effective in treating dyspigmentation.

CONCLUSION

At a preliminary level, this study revealed that 532-nm and 1,064-nm ps Nd:YAG lasers using DOE fractional technology may improve photoaged skin. In conclusion, 532-nm Nd:YAG P-DOE may be especially beneficial for skin with epidermal pigmentary lesions.

The comparison of the efficacy and safety of fractional 1064 nm Nd:YAG picosecond laser and nonablative fractional 1565 nm laser in the treatment of enlarged pores: A prospective split-face study

BACKGROUND AND OBJECTIVES

To compare the efficacy and safety of fractional 1064 nm Nd:YAG picosecond laser and nonablative fractional 1565 nm laser in the treatment of enlarged pores.

STUDY DESIGN/MATERIALS AND METHODS

Twenty patients received five monthly treatments at months 0, 1, 2, 3, and 4 and were followed up at months 5, 6, and 7. All patients were treated by fractional 1064 nm Nd:YAG picosecond laser (FxPico) on the left face, and nonablative fractional 1565 nm laser (ResurFx) on the right face as a control.

RESULTS

For the 19 patients who completed the study, both sides demonstrated significant improvement on pore counts (p < 0.01), while there was no significant difference between the two sides 3 months after the final treatment (p = 0.092). Excellence rate on the FxPico side (57.9%) was significantly better than the ResurFx side (36.8%) (p < 0.05). Sebum secretion and porphyrin value significantly decreased on both sides after five treatments and there was a higher reduction of sebum level on the ResurFx side. There was no difference between the two therapies in terms of overall satisfaction. Pain of treatment for the ResurFx side (average VAS 4.45 ± 1.60) is significantly higher than that for the FxPico side (average visual analog scale [VAS] 1.48 ± 1.36) (p < 0.001). Erythema, edema, and petechiae were common adverse effects and were mild to moderate. There was significantly higher incidence of hyperpigmentation for the ResurFx side (52.6%) compared with that for the FxPico side (5.3%) (p < 0.001).

CONCLUSION

Fractional 1064 nm Nd:YAG picosecond laser and nonablative fractional 1565 nm laser both are effective, efficient, and safe treatment regimens for enlarged pores, while fractional 1064 nm Nd:YAG picosecond laser has better clinical response with less treatment pain, shorter recovery period and much lower induction of hyperpigmentation.

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.

An update on fractional picosecond laser treatment: histology and clinical applications

Picosecond lasers have a very short pulse duration and a high peak power density. When fractional optical delivery systems are attached to picosecond lasers, they generate an array of concentrated microspots with a high fluence surrounded by areas with a low fluence. This article discusses the histologic characteristics and clinical applications of fractional picosecond laser treatment. Fractional picosecond laser produces laser-induced optical breakdown (LIOB) and laser-induced cavitation (LIC) in the epidermis and dermis respectively, and can encourage skin regeneration and dermal remodeling. It has been shown that fractional picosecond laser has a positive effect on facial photoaging, enlarged facial pores, dyspigmentation, wrinkles, and atrophic scars. Further research is still needed to confirm the benefits of fractional picosecond lasers.

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.

Functional Time Domain Diffuse Correlation Spectroscopy

Time-domain diffuse correlation spectroscopy (TD-DCS) offers a novel approach to high-spatial resolution functional brain imaging based on the direct quantification of cerebral blood flow (CBF) changes in response to neural activity. However, the signal-to-noise ratio (SNR) offered by previous TD-DCS instruments remains a challenge to achieving the high temporal resolution needed to resolve perfusion changes during functional measurements. Here we present a next-generation optimized functional TD-DCS system that combines a custom 1,064 nm pulse-shaped, quasi transform-limited, amplified laser source with a high-resolution time-tagging system and superconducting nanowire single-photon detectors (SNSPDs). System characterization and optimization was conducted on homogenous and two-layer intralipid phantoms before performing functional CBF measurements in six human subjects. By acquiring CBF signals at over 5 Hz for a late gate start time of the temporal point spread function (TPSF) at 15 mm source-detector separation, we demonstrate for the first time the measurement of blood flow responses to breath-holding and functional tasks using TD-DCS.

Review of Lasers and Energy-Based Devices for Skin Rejuvenation and Scar Treatment With Histologic Correlations

BACKGROUND

Lasers and energy-based devices (EBD) are popular treatments for skin rejuvenation and resurfacing. Achieving desired outcomes and avoiding complications require understanding the effects of these devices at a histologic level. Currently, no comprehensive review summarizing the histologic effects of laser and energy-based treatments exists.

OBJECTIVE

To describe how lasers and EBD alter skin histology and improve the overall understanding of these devices.

MATERIALS AND METHODS

A PubMed search was conducted for studies with histologic analysis of fractional picosecond laser, fractional radiofrequency microneedling, nonablative lasers, and ablative lasers.

RESULTS

Fractional picosecond lasers induce intraepidermal and/or dermal vacuoles from laser-induced optical breakdown. Fractional radiofrequency microneedling delivers thermal energy to the dermis while sparing the epidermis, making it safer for patients with darker skin phototypes. Fractional nonablative lasers induce conical zones of coagulation of the epidermis and upper dermis. Ablative lasers vaporize the stratum corneum down to the dermis. Traditional ablative lasers cause diffuse vaporization while fractional ablative lasers generate columns of tissue ablation.

CONCLUSION

Lasers and EBD are effective for skin resurfacing and rejuvenation and have different mechanisms with disparate targets in the skin. Safe and effective use of devices requires understanding the histologic laser-tissue interaction.

Study of a 532/1064 Fractional Picosecond Laser for Facial Rejuvenation

BACKGROUND AND OBJECTIVES

Picosecond (ps) fractional lasers create small wounds, presumably by laser-induced optical breakdown. We studied a ps fractional laser in the treatment of wrinkles and mottled pigment.

MATERIALS AND METHODS

This was a single center, prospective, open-label clinical trial. Patients with at least 2 facial areas, with visible wrinkles and dyschromia, were enrolled in the study and received 3 treatments at monthly intervals and appeared at 3 follow-up visits at 1, 3, and 6 months after treatment. The laser is an 800 ps fractional system with nominal 10 mm macrospot diameter. Both 532 nm and 1,064 nm wavelengths were applied in each subject. Wrinkle and pigmentation clearance were assessed by 2 blinded investigators using a 5-point clearance scale. Skin improvement was assessed by investigators using the 5-point Global Aesthetic Improvement (GAI) Scale based on before/after photographs for the following categories: (1) fine lines/wrinkles and (2) pigmentation.

RESULTS

A total of 18 healthy subjects at a single site were enrolled. At least moderate pigmentation and fine line/wrinkles improvement were observed in 93% and 79% of patients at 1 month after the last treatment according to GAI, respectively. Pigment clearance approached a mean of approximately 40%.

CONCLUSION

A ps 1,064/532 fractional laser achieves reduction in fine lines and pigment.

Treatment of abdominal striae distensae in Fitzpatrick skin types IV to V using a 1064-nm picosecond laser with a fractionated microlens array

BACKGROUND

Striae distensae are atrophic dermal scars that can cause psychosocial distress among affected patients. Despite numerous available therapeutic modalities, no gold standard treatment has been established.

OBJECTIVE

To evaluate the long-term efficacy and safety of a fractional 1064-nm picosecond laser for the treatment of striae alba in individuals with dark skin types.

MATERIALS AND METHODS

Twenty volunteers with Fitzpatrick skin types IV-V who presented with striae alba were enrolled. Subjects were treated with a fractional 1064-nm picosecond laser for four sessions at 4-week intervals. The skin texture, average melanin index (MI), and melanin variation score were assessed using Antera 3D® before treatment, at 1 month after the second treatment, and at 1, 3, and 6 months after the last treatment. Two independent investigators evaluated clinical improvement by comparing pretreatment and posttreatment photographs. The patient satisfaction rates were likewise assessed. Adverse effects were recorded during the entire study period.

RESULTS

Significant improvement of skin texture was seen at 1 month after the final treatment (p < 0.001) and continuously improved until the 6-month follow-up visit (p = 0.003). The average MI significantly increased at 1 month after the final treatment (p < 0.001), whereas the melanin variation score decreased throughout the follow-up period. Investigator assessment at the 6-month follow-up revealed that 90% of subjects had moderate to marked improvement of striae appearance. Only two of 20 subjects (10%) developed transient postinflammatory hyperpigmentation (PIH) after laser treatment.

CONCLUSION

Fractional picosecond 1064-nm laser is effective and well-tolerated for the treatment of striae alba in dark-skinned individuals with a low incidence of PIH.

Quantitative assessment of the long-term efficacy and safety of a 1064-nm picosecond laser with fractionated microlens array in the treatment of enlarged pores in Asians: A case-control study

Background

Enlarged facial pores are one of the common skin signs of photoaging that patients seek treatment for. However, objective data and long‐term assessment on the efficacy and safety of therapeutic procedures for this condition are limited.

Objective

To objectively evaluate the efficacy and safety of a 1064‐nm picosecond laser with microlens array (MLA) for pore tightening.

Methods

Twenty‐five patients with enlarged pores received three treatments with a 1064‐nm picosecond laser coupled with MLA at 4‐week intervals. Patients were evaluated using objective (measurement of pore volume using three‐dimensional photography) and subjective (clinical evaluation by two blinded dermatologists) assessments at baseline and at the 1‐, 3‐, and 6‐month follow‐ups. Adverse effects were also recorded during each visit.

Results

After three treatments, there was a significant reduction of pore size from baseline (p < 0.001). The improvement in pore size appearance significantly continued from the 1‐month to the 6‐month follow‐up visits (p = 0.013). The total average pore size was 1.15652 ± 0.614322 and 0.8087 ± 0.50515 at baseline and at 6 months after the final treatment, respectively, resulting in an average of 30% reduction in pore size. No cases of dyspigmentation, textural alteration, or scarring were documented.

Conclusion

Fractional 1064‐nm picosecond laser appears to be effective and safe for reducing pore size in Asians with minimal transient side effects.

Efficacy and Safety of Treatment with Fractional 1,064-nm Picosecond Laser with Diffractive Optic Element for Wrinkles and Acne Scars: A Clinical Study

Background

Fractional picosecond lasers is effective for the treatment of wrinkles or acne scars.

Objective

To investigate the safety and efficacy of treatment with a fractional 1,064-nm picosecond laser with a diffractive optic element for facial wrinkles and acne scars.

Methods

This prospective open-labeled trial comprised 22 subjects with facial wrinkles or acne scars. Subjects received three laser treatments with a fractional 1,064-nm picosecond laser at 3-week intervals. The efficacy and safety were evaluated at every visit and 2 months after the final treatment (14 weeks from the first treatment session). Global photographic assessments were performed by three blinded dermatologists and the subjects. Skin profilometry was performed using three-dimensional digital photographs; viscoelasticity was measured.

Results

The overall mean global improvement scores assessed by the dermatologists at weeks 3, 6, and 14, were 1.8±1.46, 2.5±1.88, and 3.5±1.84, respectively, and those assessed by the subjects were 2.7±2.08, 4.1±2.24, and 5.0±2.52, respectively. Skin profilometry showed significant improvements in the skin wrinkles, texture, depressions, and pores. The gross elasticity and skin firmness significantly improved by 10.96% and 9.04%, respectively. The major adverse reactions were erythema, pruritus, and petechiae, which disappeared within 2~3 days.

Conclusion

The fractional 1,064-nm picosecond laser is an effective and safe therapeutic modality for skin rejuvenation.

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.

Wound Healing Profile After 1064- and 532-nm Picosecond Lasers With Microlens Array of In Vivo Human Skin

BACKGROUND AND OBJECTIVES

The aim of this study is to histologically characterize the wound healing process of in vivo human skin treated with 1064- and 532-nm microlens array (MLA)-type picosecond lasers.

STUDY DESIGN/MATERIALS AND METHODS

Three patients (Fitzpatrick skin types II-IV), who were undergoing future cosmetic abdominoplasties, were treated with 1064- and 532-nm MLA-type lasers under different fluence settings. Treatments were performed 2 weeks, 1 week, and immediately prior to surgery. Skin samples were harvested from the resected tissue with 8 mm punch biopsies immediately after the abdominoplasties were performed.

RESULTS

The study demonstrates that intraepidermal vacuoles, created from tissue damage induced by the laser, are histologically resolved within 1 week without persistent damage to the dermoepidermal junction or vasculature. After 2 weeks, all foci of microscopic epidermal necrotic debris had either resolved or migrated to more superficial levels in the stratum corneum. There was no evidence of persistent vascular damage, increased melanophages, or accumulation of melanin in the dermis at 2 weeks. Furthermore, the 1064-nm picosecond laser with the high fluence setting demonstrated the capacity to fractionally ablate the epidermis and induce multifocal fibrosis in the papillary dermis in lighter skin types.

CONCLUSION

This is the first study to demonstrate the wound healing profile of in vivo human skin after treatment with the picosecond 1064- and 532-nm MLA-type lasers. It shows that laser-induced tissue damage is histologically resolved within 2 weeks, clinically reflecting a favorable safety profile and short downtime. The study also shows that the picosecond laser can be used to induce either fractional ablative or non-ablative effects, depending on the fluence settings used. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Histological Characteristics of Skin Treated With a Fractionated 1064-nm Nd: YAG Picosecond Laser With Holographic Optics

BACKGROUND AND OBJECTIVES

Picosecond lasers (PSL) constitute a significant technological advancement and exert rejuvenating effects upon the skin. This study was conducted to investigate changes in the skin upon treatment with the fractionated 1064-nm Nd: YAG PSL through in vivo and ex vivo human histological analysis.

STUDY DESIGN/MATERIALS AND METHODS

In vivo back skin specimens were treated with a fractionated 1064-nm PSL at 1.3, 2.1, and 2.9 mJ fluence for two passes, and 2.9 mJ for 10 passes, and then stained with hematoxylin and eosin (H&E). Ex vivo foreskin specimens after circumcision surgery were treated with a PSL at 1.3, 2.1, and 2.9 mJ fluence for two and 10 passes, followed by H&E staining. Ex vivo skin tissue sections treated with a PSL at 2.9 mJ fluence for 10 passes were also immunostained for Melan-A and CD31.

RESULTS

Intraepidermal vacuoles were observed, along with pigment accumulation and inflammatory cell infiltration in the vacuoles at 24 hours after PSL treatment in the in vivo skin specimens. The vacuoles expanded as the fluence increased. Numerous intraepidermal vacuoles were observed, with dermal hemorrhage and inflammatory cell infiltration upon high-fluence, multi-pass PSL treatment in the in vivo skin specimens. PSL treatment yielded both epidermal and dermal vacuoles in ex vivo skin specimens. Melan-A-positive cells were seen in the cystic wall of vacuoles in the epidermal basal layer, whereas CD31-positive cells were detected in the cystic wall of some dermal vacuoles.

CONCLUSIONS

The fractionated 1064-nm PSL produced epidermal vacuoles and dermal lesions, with histological differences between the in vivo and ex vivo skin specimens. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Objective and Long-Term Evaluation of the Efficacy and Safety of a 1064-nm Picosecond Laser With Fractionated Microlens Array for the Treatment of Atrophic Acne Scar in Asians

BACKGROUND AND OBJECTIVE

Fractional 1064-nm picosecond-domain laser has recently been utilized for the treatment of atrophic acne scars and showed promising results. However, data on the safety and efficacy of this procedure in dark-skinned patients are limited. This prospective, self-controlled study was conducted to objectively evaluate the safety and efficacy of a 1064-nm picosecond laser coupled with a microlens array (MLA) for the treatment of atrophic acne scars on Asian skin.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-six subjects of Fitzpatrick skin types (FSTs) III and IV with atrophic acne scars were enrolled. All subjects were treated with a 1064-nm picosecond laser (spot size of 8 mm, fluence of 1.0 J/cm² , a repetition rate of 10 Hz) in combination with the MLA handpiece for an average of three passes, for 6 monthly sessions. Objective (measurement of scar volume using three-dimensional (3D) photography and skin roughness analysis using ultraviolet A-light video camera) and subjective (clinical evaluation by two blinded dermatologists) assessments were obtained at baseline and at 1, 3, and 6 months after the final treatment.

RESULTS

Statistically significant reduction of the scar volume from baseline at 1, 3, and 6 months after the final treatment were observed by 3D photography and ultraviolet A-light video camera. At the 6-month follow-up, 50% (13 of 26) of the subjects were rated as having at least 50% improvement of the scars. The rate of improvement significantly increased from the 1-month follow-up to the 6-month follow-up (P = 0.013). Similarly, at the 6-month follow-up, the scar volume (P = 0.024) and skin roughness (P = 0.001) also significantly improved, in comparison with the baseline. Mild postinflammatory hyperpigmentation (PIH) was observed to develop in approximately 18% of all the treatment sessions. All cases of PIH were temporary and resolved within 4 weeks on average.

CONCLUSIONS

The 1064-nm picosecond laser with MLA is a safe therapeutic alternative for the treatment of atrophic acne scars in dark-skinned individuals. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Laser-induced optical breakdown effects of micro-lens arrays and diffractive optical elements on ex vivo porcine skin after 1064 nm picosecond laser irradiation

The current study aims to investigate the effects of micro-lens arrays (MLA) and diffractive optical elements (DOE) on skin tissue via intra-dermal laser-induced optical breakdown (LIOB) after irradiation of 1064-nm picosecond laser light at high energy settings. Irradiation with MLA and DOE was tested on dimming paper, tissue-mimicking phantom, and dark pigmented porcine skin to quantitatively compare distributions of micro-beams, micro-bubbles, and laser-induced vacuoles in the skin. DOE yielded more uniform distributions of the micro-beams on the paper and laser-induced micro-bubbles in the phantom, compared to MLA. The ex vivo skin test confirmed that the DOE-assisted irradiation accompanied more homogeneous generation of the micro-beams on the tissue surface (deviation of ≤ 3%) and a high density of small laser-induced vacuoles (∼78 µm) in the dermis than the MLA-assisted irradiation (deviation of ∼26% and ∼163 µm). The DOE-assisted picosecond laser irradiation may help to achieve deep and uniformly-generated vacuolization under the basal membrane after intra-dermal LIOB for effective fractional skin treatment.

A randomized split-face, investigator-blinded study of a picosecond Alexandrite laser for post-inflammatory erythema and acne scars

The 755 nm picosecond Alexandrite laser has been demonstrated to be effective and well tolerated in patients with acne scars. In this split-face, investigator-blinded study, 16 patients with post-inflammatory erythema (PIE) and acne scars were randomized to receive laser treatment on half the face, with the other half serving as a control. The treatment side demonstrated a significant improvement in both PIE and scars compared to the baseline and also when compared to the control side. Treatment was well-tolerated, with only transient and mild erythema and edema reported as side-effects. In our study, the picosecond Alexandrite laser was safe and effective in the treatment of PIE and acne scars. Comprehensive treatment outcomes should be taken into consideration when deciding on which device to use.

Efficient Picosecond Laser for Tattoo Removal in Rat Models

Background

Tattoos are popular in modern times. Due to the occurance of adverse effects such as poor aesthetic value, scar hyperplasia, and abnormal pigments, there is a high demand for uniform operation standards as well as standards for tattoo technologies. In the present study we used Sprague-Dawley rats to assess the tattoo removal efficacy of use of a picosecond laser at various energy values.

Material/Methods

Tattoos were made on the backs of rats, then we used a picosecond laser set at various energy parameters to remove the tattoos. After performing the removal procedure in multiple groups, we selected the most suitable energy levels with corresponding parameters for the tattoo removal. We recruited human volunteers who wanted their tattoos removed and used the energy level found to perform best during tattoo removal experiments. The tattoo removal effects were evaluated and verified. Four tattoo volunteers were treated by using the optimal energy parameters for picosecond laser technology.

Results

Through characterization observation and pathological staining results, it was demonstrated that the 1.9 mJ/μbeam energy laser had the best hollowing effect and the most complete pigment particle crushing effect in the rat skin, and had the best tattoo removal effect.

Conclusions

We leveraged the evaluation standard to choose the most suitable energy value of the picosecond laser, which had a good tattoo removal effect and could be employed as a reference for clinical removal of tattoos. This process provides criteria for tattoo removal evaluations as well as alternatives for tattoo removal in clinical practice.

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.

A Randomized, Split-Face, Double-Blind Comparison Trial Between Fractionated Frequency-Doubled 1064/532 nm Picosecond Nd:YAG Laser and Fractionated 1927 nm Thulium Fiber Laser for Facial Photorejuvenation

BACKGROUND AND OBJECTIVE

Fractionated lasers are a popular therapeutic option for facial photorejuvenation. In this study, we compare the safety, tolerability, and efficacy of a fractionated frequency-doubled 1064/532 nm picosecond Nd:YAG fractionated picosecond laser (FPL) versus a fractionated 1927 nm thulium fiber laser (TFL) for facial rejuvenation.

STUDY DESIGN/MATERIALS AND METHODS

This was a double-blind, randomized, split-face comparison study involving 20 subjects. Facial halves were randomized to receive either FPL or TFL treatment. Three treatments were delivered at 1-month intervals. Subjects were followed up for 1, 3, and 6 months post-final treatment session and evaluated by blinded, non-treating investigators for dyspigmentation, erythema, keratosis, texture, and rhytids on a standardized scale. Subjects also recorded a quantitative daily diary rating healing progress for 14 days after every treatment session.

RESULTS

Statistically significant improvements in elastosis, erythema, keratosis, dyschromia, and skin texture were noted in both treatment groups. There were no significant differences detected in clinical efficacy between the two groups. Subject daily dairies revealed statistically significant differences in tolerability during the immediate 14-day post-operative recovery period. The facial half treated with FPL displayed significantly less redness on days 3 and 4; significantly less swelling on day 5; significantly less crusting on days 1 through 9; significantly less peeling on days 3 through 9; and significantly less itch on days 4 and 7. There were no unexpected adverse effects observed.

CONCLUSION

Both FPL and TFL are safe and effective treatment options for facial rejuvenation. FPL may be associated with significantly less downtime. Lasers Surg. Med. © 2020 Wiley Periodicals, Inc.

Interactive tissue reactions of 1064-nm focused picosecond-domain laser and dermal cohesive polydensified matrix hyaluronic acid treatment in in vivo rat skin

BACKGROUND

Picosecond-domain laser treatment using a microlens array (MLA) or a diffractive optical element (DOE) generates micro-injury zones in the epidermis and upper dermis.

OBJECTIVE

To investigate interactive tissue reactions between MLA-type picosecond laser pulses and cohesive polydensified matrix hyaluronic acid (CPMHA) filler in the dermis.

METHODS

In vivo rats with or without CPMHA pretreatment were treated with a 1064-nm picosecond-domain neodymium:yttrium-aluminum-garnet (Nd:YAG) laser using an MLA or DOE. Skin samples were obtained at post-treatment days 1, 10, and 21 and histologically and immunohistochemically analyzed.

RESULTS

Picosecond-domain Nd:YAG laser treatment with an MLA-type or a DOE-type handpiece generated fractionated zones of pseudo-cystic cavitation along the lower epidermis and/or upper papillary dermis at Day 1. At Day 21, epidermal thickness, dermal fibroblasts, and collagen fibers had increased. Compared to CPMHA-untreated rats, rats pretreated with CPMHA showed marked increases in fibroblasts and collagen fibers in the papillary dermis. Immunohistochemical staining for the hyaluronic acid receptor CD44 revealed that MLA-type picosecond laser treatment upregulated CD44 expression in the basilar epidermis and dermal fibroblasts.

CONCLUSIONS

We suggest that the hyaluronic acid-rich environment associated with CPMHA treatment may enhance MLA-type picosecond-domain laser-induced tissue reactions in the epidermis and upper dermis.

A Prospective Study of Fractionated Dual-Wavelength Picosecond Laser in Treating Acne Scar

BACKGROUND AND OBJECTIVES

The picosecond (PICO) laser has been a new and promising device. But, so far, there have not been many prospective studies investigating the efficacy in acne scar treatment. This study evaluated the efficacy and safety of the dual-wavelength picosecond laser in the treatment of acne scar.

STUDY DESIGN/MATERIALS AND METHODS

A total of 20 patients with skin type III-IV were enrolled in this study. Eighteen patients completed the study. All patients completed six treatment sessions within a 1-month interval. All patients were treated using both 532 and 1,064 nm fractionated dual-wavelength picosecond handpieces. In evaluation, Goodman and Baron's quantitative global acne scarring grading system (GSS) was scored by two physicians. Patients also judged the results themselves by Visual Analog Scale (VAS) and pain score.

RESULTS

The average baseline score of GSS quantity and quality were 15.22 and 3.00, respectively. The final scores were 10.61 and 2.33. The average baseline of patient VAS score was 4.28. The final score was 2.00. All scores achieved statistical significance (P < 0.05). No serious long-term side effects were recorded.

CONCLUSION

Acne scar treatment with the fractionated dual-wavelength picosecond laser has shown both efficacy and safety in this study. Lasers Surg. Med. © 2020 Wiley Periodicals, Inc.

Histology of ex vivo skin after treatment with fractionated picosecond Nd:YAG laser in high and low-energy settings

Background: The fractionated picosecond laser produces microscopic lesions in the epidermis and dermis, which are known as laser-induced optical breakdown (LIOB) and intra-dermal laser-induced cavitation (LIC). There have been multiple histological reports on these phenomena, although some have been challenged on the grounds of similarity to artifacts. Asian skins, with a higher melanin content, may react differently to this treatment, and present literature is also lacking in this area.Purpose: To observe and report the histological effect of different energy levels and parameters of the fractional 532 nm/1064 nm picosecond laser on Asian skin ex vivo.Methods: Six skin samples were taken from clinically normal-looking perilesional areas and treated with different energy levels and parameters of the fractional 532 nm/1064 nm picosecond laser. The specimens were then sent to the lab for H&E staining, and the slides were reviewed by a dermatopathologist.Results: Superficial, intra-epidermal LIOBs were seen in skin treating at higher laser energies; deep, intra-dermal LICs were seen in skin treated at lower energies. Lesion sizes and depths were consistent with previously reported values on Caucasian skins, and lesions were spaced in 600-μm intervals or its multiple.Conclusions: The histological findings are consistent with results from other ethnicities, and the spacing of lesions is a strong indication of their validity as LIOBs or LICs.

Pattern analysis of 532- and 1,064-nm picosecond-domain laser-induced immediate tissue reactions in ex vivo pigmented micropig skin

Optical pulses from picosecond lasers can be delivered to the skin as single, flat-top beams or fractionated beams using a beam splitter or microlens array (MLA). In this study, picosecond neodymium:yttrium aluminum garnet laser treatment using a single flat-top beam and an MLA-type beam at the wavelengths of 532 nm and 1,064 nm were delivered on ex vivo genotype-regulated, pigmented micropig skin. Skin specimens were obtained immediately after treatment and microscopically analyzed. Single flat-top beam treatment at a wavelength of 532 nm and a fluence of 0.05-J/cm² reduced melanin pigments in epidermal keratinocytes and melanocytes, compared to untreated controls. Additionally, 0.1 J/cm²- and 1.3 J/cm²-fluenced laser treatment at 532 nm elicited noticeable vacuolation of keratinocytes and melanocytes within all epidermal layers. Single flat-top beam picosecond laser treatment at a wavelength of 1,064 nm and a fluence of 0.18 J/cm² also reduced melanin pigments in keratinocytes and melanocytes. Treatment at 1,064-nm and fluences of 1.4 J/cm² and 2.8 J/cm² generated increasing degrees of vacuolated keratinocytes and melanocytes. Meanwhile, 532- and 1,064-nm MLA-type, picosecond laser treatment elicited fractionated zones of laser-induced micro-vacuolization in the epidermis and dermis. Therein, the sizes and degrees of tissue reactions differed according to wavelength, fluence, and distance between the microlens and skin.

Laser assisted tattoo removal – state of the art and new developments

Decorative tattoos including permanent make-up are very popular world-wide. As the trend for tattoo acquisition increases, the demand for tattoo removal will similarly rise. This article highlights the state of the art and new developments in laser assisted tattoo removal.

A randomized, single-blind, study evaluating a 755-nm picosecond pulsed Alexandrite laser vs. a non-ablative 1927-nm fractionated thulium laser for the treatment of facial photopigmentation and aging

Background: Laser toning is one of the most popular strategies to treat facial photopigmentation and aging. Several laser modalities, including fractional non-ablative, Q-switched (QS) lasers and new generation picosecond lasers have been used for this indication. However, there is paucity of head to head comparisons of older generation of lasers with new ones. Objective: To compare a 755 nm picosecond pulsed alexandrite laser with a non-ablative 1927 nm fractionated thulium laser for the treatment of facial photopigmentation and aging through a randomized, single-blind study. Materials and methods: 20 subjects (skin types I-IV) were randomized to receive either four 755-nm picosecond alexandrite laser treatments, spaced 3 weeks apart, or two dual wavelength thulium fiber fractionated 1550/1927 nm laser treatments, spaced 6 weeks apart. Follow-up assessment visits occurred 4 and 12 weeks after the last study treatment. Results: At the 4- and 12-week follow-up, both groups showed significant improvement of photoaging, pigmentation, skin quality according to the investigator and subjects assessments. When comparing the two groups, subjects in 755 nm group had statistically significant greater improvement in investigator assessments of photoaging/skin quality and subject satisfaction than those in the 1927 nm group. Conclusion: Both the non-ablative 1927 and 755 nm picosecond laser can improve facial photopigmentation, but the latter can yield superior results with less pain and side effects according to patient and investigator assessments.