-
Actas Dermo-sifiliograficas 2022Burn scars cause high morbidity in the form of contractures, body disfigurement, and itching, and they also have a high emotional impact that adversely affects patient... (Review)
Review
Burn scars cause high morbidity in the form of contractures, body disfigurement, and itching, and they also have a high emotional impact that adversely affects patient quality of life. Laser therapy has proven effective in this setting. It is superior to topical treatments and can be used in conjunction with surgery, helping to reduce morbidity. The use of lasers in hospital dermatology departments, however, is still limited. Carbon dioxide laser resurfacing is the most widely used modality for reducing scar thickness, improving textural abnormalities, and treating contractures. Treatments improve mobility for patients with constrictions. Pulsed dye laser treatments are particularly useful for reducing erythema in recent burn scars and preventing subsequent hypertrophy. Pigment laser treatments with short pulse durations (nanoseconds or picoseconds) can improve hyperpigmentation. In this article, we review the evidence for the use of laser therapy for burn scars and propose a treatment algorithm.
Topics: Humans; Cicatrix; Cicatrix, Hypertrophic; Lasers, Gas; Burns; Quality of Life; Laser Therapy; Contracture; Treatment Outcome
PubMed: 35963335
DOI: 10.1016/j.ad.2022.06.018 -
Lasers in Medical Science Jan 2023Picosecond lasers have a very short pulse duration and a high peak power density. When fractional optical delivery systems are attached to picosecond lasers, they... (Review)
Review
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.
Topics: Humans; Lasers, Solid-State; Skin; Epidermis; Cicatrix; Pigmentation Disorders; Treatment Outcome
PubMed: 36658259
DOI: 10.1007/s10103-022-03704-y -
Dermatologie (Heidelberg, Germany) Jun 2023The picosecond laser is one of the latest laser systems in dermatology and was originally developed to optimize tattoo removal. Advances in this technology has expanded... (Review)
Review
BACKGROUND
The picosecond laser is one of the latest laser systems in dermatology and was originally developed to optimize tattoo removal. Advances in this technology has expanded the use of the picosecond laser to numerous other indications.
OBJECTIVES
This article provides an overview of the technical background as well as the indications of the picosecond laser in dermatological laser medicine and elucidates the possibilities and limits of this laser system.
MATERIALS AND METHODS
The article is based on a review of the current literature as well as experience from clinical practice in a university laser department.
RESULTS
The picosecond laser enables a particularly gentle and effective treatment due to ultra-short pulses and the principle of laser-induced optical breakdown. Compared to Q‑switched lasers, the picosecond laser has fewer side effects and is associated with lower pain intensity and shorter downtime. In addition to the removal of tattoos and pigmentary disorders, it is also used in the treatment of scars and rejuvenation.
CONCLUSIONS
The picosecond laser has a wide range of indications in dermatological laser medicine. The current data indicate that the laser is an effective method with few side effects. Further prospective studies have to be conducted to assess the efficacy, tolerability and patient satisfaction in an evidence-based manner.
Topics: Humans; Prospective Studies; Dermatology; Lasers; Tattooing; Laser Therapy; Drug-Related Side Effects and Adverse Reactions
PubMed: 37099130
DOI: 10.1007/s00105-023-05144-3 -
Frontiers in Physics 2023Brillouin microscopy based on spontaneous Brillouin scattering has emerged as a unique elastography technique because of its merit of non-contact, label-free, and...
Brillouin microscopy based on spontaneous Brillouin scattering has emerged as a unique elastography technique because of its merit of non-contact, label-free, and high-resolution mechanical imaging of biological cell and tissue. Recently, several new optical modalities based on stimulated Brillouin scattering have been developed for biomechanical research. As the scattering efficiency of the stimulated process is much higher than its counterpart in the spontaneous process, stimulated Brillouin-based methods have the potential to significantly improve the speed and spectral resolution of existing Brillouin microscopy. Here, we review the ongoing technological advancements of three methods, including continuous wave stimulated Brillouin microscopy, impulsive stimulated Brillouin microscopy, and laser-induced picosecond ultrasonics. We describe the physical principle, the representative instrumentation, and biological application of each method. We further discuss the current limitations as well as the challenges for translating these methods into a visible biomedical instrument for biophysics and mechanobiology.
PubMed: 37377499
DOI: 10.3389/fphy.2023.1175653 -
Sensors (Basel, Switzerland) Apr 2021Fast gating in Raman spectroscopy is used to reject the fluorescence contribution from the sample and/or the substrate. Several techniques have been set up in the last... (Review)
Review
Fast gating in Raman spectroscopy is used to reject the fluorescence contribution from the sample and/or the substrate. Several techniques have been set up in the last few decades aiming either to enhance the Raman signal (CARS, SERS or Resonant Raman scattering) or to cancel out the fluorescence contribution (SERDS), and a number of reviews have already been published on these sub-topics. However, for many reasons it is sometimes necessary to reject fluorescence in traditional Raman spectroscopy, and in the last few decades a variety of papers dealt with this issue, which is still challenging due to the time scales at stake (down to picoseconds). Fast gating (<1 ns) in the time domain allows one to cut off part of the fluorescence signal and retrieve the best Raman signal, depending on the fluorescence lifetime of the sample and laser pulse duration. In particular, three different techniques have been developed to accomplish this task: optical Kerr cells, intensified Charge Coupling Devices and systems based on Single Photon Avalanche Photodiodes. The utility of time domain fast gating will be discussed, and In this work, the utility of time domain fast gating is discussed, as well as the performances of the mentioned techniques as reported in literature.
PubMed: 33916972
DOI: 10.3390/s21082579 -
Photoacoustics Jun 2023This review discusses picosecond ultrasonics experiments using ultrashort hard x-ray probe pulses to extract the transient strain response of laser-excited nanoscopic... (Review)
Review
This review discusses picosecond ultrasonics experiments using ultrashort hard x-ray probe pulses to extract the transient strain response of laser-excited nanoscopic structures from Bragg-peak shifts. This method provides direct, layer-specific, and quantitative information on the picosecond strain response for structures down to few-nm thickness. We model the transient strain using the elastic wave equation and express the driving stress using Grüneisen parameters stating that the laser-induced stress is proportional to energy density changes in the microscopic subsystems of the solid, i.e., electrons, phonons and spins. The laser-driven strain response can thus serve as an ultrafast proxy for local energy-density and temperature changes, but we emphasize the importance of the nanoscale morphology for an accurate interpretation due to the Poisson effect. The presented experimental use cases encompass ultrathin and opaque metal-heterostructures, continuous and granular nanolayers as well as negative thermal expansion materials, that each pose a challenge to established all-optical techniques.
PubMed: 37275326
DOI: 10.1016/j.pacs.2023.100503 -
Laser Therapy Jul 2020Rejuvenation therapy using picosecond pulse laser and picosecond pulsed fractional therapy with a fractional lens have been performed with clinical effects evaluated....
BACKGROUND AND AIMS
Rejuvenation therapy using picosecond pulse laser and picosecond pulsed fractional therapy with a fractional lens have been performed with clinical effects evaluated. However, no histological analysis of effects on photoaged skin exists. In this study, influence of laser-toning and fractional therapy using picosecond pulse laser on photoaging was histologically investigated.
SUBJECTS AND METHODS
The flexor side forearm of a male, age 61, with photoaging was divided into three 20 cm areas and irradiated with approximately 400 shots of 10-Hz laser, 8 mm spot size, and nine passes at an output of 0.7, 0.9, and 1.1 J/cm using picosecond laser-toning therapy six times, every two weeks. Two weeks post final irradiation, 2 mm punch biopsies were taken from the irradiation fields. Fractional therapy using Micro Lens Array (MLA) attached picosecond fractional therapy was applied to the medial crural skin with marked photoaging of a male, age 63. Irradiation was applied at 0.5 and 0.7 J/cm through two passes, with 3 mm punch biopsies taken from each irradiation field immediately after and again two months post-irradiation. Samples were subjected to hematoxylin and eosin (HE) and Elastica van Gieson staining and compared.
RESULTS
In the picosecond laser-toning therapy sample, photoaging-induced dermis reconstruction occurred. The picosecond fractional therapy sample showed both epidermis and dermis reconstruction, with intrinsic aging and photoaging improvements.
CONCLUSIONS
Recovery of dermal and epidermal age related atrophy by picosecond laser-toning and picosecond fractional therapy was histologically confirmed. Picosecond fractional therapy demonstrated superior improvement.
PubMed: 32904059
DOI: 10.5978/islsm.20-OR-05 -
Frontiers in Medicine 2023Increasing numbers of studies demonstrated that picosecond lasers (Picos) were effective and safe for melasma. However, A limited number of randomized controlled trials...
Comparison of the efficacy and safety of picosecond Nd:YAG laser (1,064 nm), picosecond alexandrite laser (755 nm) and 2% hydroquinone cream in the treatment of melasma: A randomized, controlled, assessor-blinded trial.
BACKGROUND
Increasing numbers of studies demonstrated that picosecond lasers (Picos) were effective and safe for melasma. However, A limited number of randomized controlled trials (RCTs) regarding Picos contribute to a modest level of evidence. Topical hydroquinone (HQ) remains to be the first-line therapy.
OBJECTIVE
To compare the efficacy and safety of non-fractional picosecond Nd:YAG laser (PSNYL), non-fractional picosecond alexandrite laser (PSAL), and 2% HQ cream in the treatment of melasma.
METHOD
Sixty melasma patients with Fitzpatrick skin types (FST) III-IV were randomly assigned to the PSNY, PSAL, and HQ groups at a 1:1:1 ratio. Patients in PSNYL and PSAL groups received 3 laser sessions at 4-week intervals. The 2% HQ cream was applied twice daily for 12 weeks in patients of the HQ group. The primary outcome, the melasma area and severity index (MASI) score, was evaluated at weeks 0, 4, 8, 12, 16, 20, and 24. The patient assessment score by quartile rating scale was rated at weeks 12, 16, 20, and 24.
RESULTS
Fifty-nine (98.3%) subjects were included in the analysis. Each group showed significant change from baseline in MASI scores from week 4 to week 24. The MASI score in the PSNYL group showed the greatest reduction compared to the PSAL group ( = 0.016) and HQ group ( = 0.018). The PSAL group demonstrated comparable MASI improvement as the HQ group ( = 0.998). The PSNYL group had the highest patient assessment score, followed by the PSAL group and then the HQ group, although only the differences between PSNYL and HQ groups at weeks 12 and 16 were significant. Four patients (6.8%) experienced recurrence. Other unanticipated events were transient and subsided after 1 week to 6 months.
CONCLUSION
The efficacy of non-fractional PSNYL was superior to that of non-fractional PSAL, which was not inferior to 2% HQ, thus non-fractional Picos providing an alternative for melasma patients with FSTs III-IV. The safety profiles of PSNYL, PSAL, and 2% HQ cream were similar.
CLINICAL TRIAL REGISTRATION
https://www.chictr.org.cn/showprojen.aspx?proj=130994, ChiCTR2100050089.
PubMed: 37056729
DOI: 10.3389/fmed.2023.1132823 -
Clinical, Cosmetic and Investigational... 2021We aimed to investigate picosecond laser effects regarding rat tattoo removals. We systematically detected the metabolic pathways considering tattoo pigment particles in...
OBJECTIVE
We aimed to investigate picosecond laser effects regarding rat tattoo removals. We systematically detected the metabolic pathways considering tattoo pigment particles in rat models.
MATERIALS AND METHODS
We employed fluorescein to mark the tattoo dye and utilized a pattern needle to prepare tattoo on rat so as to establish the tattoo removal effects of picosecond laser methods employing animal models. We applied a picosecond laser to process the tattoo and observed the effects along with metabolic pathways for tattoo removal via pathology and imaging approaches.
RESULTS
Based on the results of characterization, pathology and fluorescence, we discovered that the picosecond laser could effectively remove the pigment particles on rat skin, part of which would be metabolized out of the body through the circulatory system. After picosecond laser treatment, the fluorescence intensity of the rat skin engraved part was gradually weakened. At 8 h after the treatment, the metabolic organs had weak fluorescence, and there was no fluorescence in the metabolic organs at 12 h and 24 h after the treatment.
CONCLUSION
The picosecond laser had perfect tattoo removal effects, which could be utilized as a reference for clinical tattoo removal.
PubMed: 34594124
DOI: 10.2147/CCID.S332265 -
Materials (Basel, Switzerland) Sep 2023In this work, we present the fabrication of thin films/nanostructures of metals and metal oxides using picosecond laser ablation. Two sets of experiments were performed:...
In this work, we present the fabrication of thin films/nanostructures of metals and metal oxides using picosecond laser ablation. Two sets of experiments were performed: the depositions were carried out in vacuum and in air at atmospheric pressure. The subjects of investigation were the noble metals Au and Pt and the metal oxides ZnO and TiO. We studied and compared the phase composition, microstructure, morphology, and physicochemical state of the as-deposited samples' surfaces in vacuum and in air. It was found that picosecond laser ablation performed in vacuum led to the fabrication of thin films with embedded and differently sized nanoparticles. The implementation of the same process in air at atmospheric pressure resulted in the fabrication of porous nanostructures composed of nanoparticles. The ablation of pure Pt metal in air led to the production of nanoparticles with an oxide shell. In addition, more defects were formed on the metal oxide surface when the samples were deposited in vacuum. Furthermore, the laser ablation process of pure Au metal in a picosecond regime in vacuum and in air was theoretically investigated using molecular dynamics simulation.
PubMed: 37834498
DOI: 10.3390/ma16196364