Applications of the Excimer Laser

An in vitro feasibility study of 355 nm laser atherectomy for the treatment of peripheral atherosclerotic lesions

In this study, we utilized a novel 355 nm laser to ablate porcine aortas in the presence of physiological saline and contrast agent. Subsequently, we investigated the shape and depth of the resulting injuries. After ablating bovine tendons and aortas with the laser, we analyzed the size and quantity of particles postablation. Finally, we conducted ablation experiments using human ex vivo plaques. The analysis revealed minimal damage to porcine aortas within 2 s of exposure to the 355 nm laser. The degree of injury in the presence of contrast agent was higher than that in the presence of physiological saline but significantly lower than the damage caused by 308 nm laser. Regardless of whether it was bovine tendon or porcine aorta tissue, the proportion of particles <25 μm postlaser ablation exceeded 99%. Lastly, the 355 nm laser successfully opened three types of plaques: chronically occluded, stent restenosis, and stale thrombosis.

Efficacy and safety of excimer light (308 nm) in the treatment of pityriasis lichenoides chronica

INTRODUCTION

Pityriasis lichenoides chronica is the chronic end of the spectrum of pityriasis lichenoides which have several forms of papulosuamous conditions. Several treatments obtained complete clearance of the condition including phototherapy and specifically narrow band ultraviolet B. The Excimer light 308 is a monochromatic light that acts within the ultraviolet B wavelength and used as a targeted phototherapy in several skin conditions.

METHODS

Thirty-four patients with histopathologically diagnosed pityriasis lichenoides chronica underwent treatment with biweekly sessions of excimer light 308 nm. Treatment continued until complete clearance was obtained or to a maximum of 48 sessions (24 weeks).

RESULTS

Thirty-one patients obtained complete clearance with no recurrence till the end of the study period, two patients had partial response and only one patient showed poor response to treatment.

CONCLUSION

Excimer light can be a safe and effective treatment of pityriasis lichinoides chronica in different ages and genders.

Excimer light effect on neurogenic inflammation in active versus stable psoriasis lesions

Neurogenic inflammation, mediated by T helper 17 cell (Th17) and neurons that release neuropeptides such as substance P (SP), is thought to play a role in the pathogenesis of psoriasis. Excimer light is used in the treatment of psoriasis via induction of T cell apoptosis. The objective of this study is to study the effect of excimer light on active versus stable psoriasis and investigate the levels of substance P and its receptor in both groups. The study included 27 stable and 27 active psoriatic patients as well as 10 matched healthy controls. Clinical examination (in the form of local psoriasis severity index (PSI) and visual analogue scale (VAS)) was done to determine disease severity, level of itching, and quality of life. Tissue levels of SP and neurokinin-1 receptor (NK-1R) were measured by ELISA before and after 9 excimer light sessions in 43 patients. A statistically significant lower levels of PSI and VAS were reached after therapy with no significant difference between the stable and active groups. The mean tissue levels of SP before therapy were significantly higher than the control group. Lower levels of SP and NK-1 receptor were found after treatment overall and in each group. Excimer therapy can be effective for both stable and active plaque psoriasis and this effect could be partly through its role on ameliorating the neurogenic inflammation.

Excimer Laser System: The Revolutionary Way to Treat Psoriasis

Psoriasis is a chronic, autoinflammatory skin disease that affects approximately 100 million people worldwide. It is a systemic disease characterized by scaly, red patches on the skin and can also affect the joints. Psoriasis can significantly affect a person's physical and mental health. The prevalence rate of psoriasis may vary depending on the specific population studied and the diagnostic criteria used. Phototherapy is a safe and effective treatment for psoriasis that involves exposing the affected skin to specific wavelengths of light. It can be used alone or with other treatments for severe psoriasis. However, clinicians must choose the right light source for each type of psoriasis and monitor the patient closely during treatment to avoid adverse events. The 308 nm excimer laser is a widely used device in dermatology for treating several skin conditions, including psoriasis. Although the excimer laser can treat various dermatologic diseases, this study will focus only on its effectiveness in treating psoriasis. This study will review the use of an excimer laser, its protocol, and its side effects.

Effect of sodium fluorescein strip application on cornea parameters commonly used in laser-assisted in-situ keratomileusis

To assess the effect of sodium fluorescein (NaF) strip on corneal parameters commonly used in Laser-assisted in-situ keratomileusis (LASIK). Eighty-six subjects (172 eyes) scheduled for LASIK were recruited between January and March 2022. The study and statistical analysis test were conducted in April 2022. Topographic measurements of corneal parameters, including central corneal thickness (CCT), anterior keratometric (K) readings (K1, flat keratometry; K2, steep keratometry), horizontal corneal diameter (white to white, WTW), and corneal asphericity (Q value), were obtained using a Scheimpflug device (Pentacam) before and 10 min after NaF strip treatmentThe Pentacam recorded a small significant increase in CCT (mean 538.88 ± 28.78 μm to 547.90 ± 29.94 μm; p < .001), with no differences in K1 and K2 (mean 42.24 ± 1.35D to 42.24 ± 1.35D, and mean 43.34 ± 1.50D to 43.32 ± 1.51D; P > .05, for all) as well as WTW(mean 11.58 ± 0.32 mm to 11.58 ± 0.32 mm, P > .05) before and after NaF strip intervention. Furthermore, there was no significant difference was observed in Q value (mean - 0.30 ± 0.13 to - 0.30 ± 0.14, P > .05). These results indicate that clinicians should avoid NaF strip application before obtaining precise topographic measurements of cornea parameters using the Pentacam.

Weekly phototherapy is an effective therapy for patients with vitiligo

The current strategies for the treatment of vitiligo using phototherapy usually involve treatment for two-three times per week; however, in practice, the number of patient sessions does not meet this standard. The present study found that phototherapy once a week was also effective. The present study was designed to examine the efficacy of weekly light therapy. For this purpose, 296 patients with vitiligo were included and divided into five sub-samples of the neck, face, trunk, extremities and scalp according to the site of phototherapy, and were treated once or twice weekly with phototherapy. The difference in efficacy between phototherapy performed once and twice weekly was observed using a Chi-squared test. It was concluded that there was a minimal difference between phototherapy performed twice weekly compared to once weekly for the treatment of vitiligo on the face, neck, torso, limbs and scalp. Thus, phototherapy once a week is valid for the treatment of vitiligo, although weekly light therapy takes longer to restore color for the first time.

Real scenario of metal ion sensor: is conjugated polymer helpful to detect hazardous metal ion

Metal ions from natural and anthropogenic sources cause pollution to society and the environment is major concern in the present scenario. The deposition and contamination of metal ions in soil and water affect the biogeochemical cycles. Thus, it threatens the everyday life of living and non-living organisms. Reviews on the detection of metal ions through several techniques (Analytical methods, electrochemical techniques, and sensors) and materials (Nanoparticles, carbon dots (quantum dots), polymers, chiral molecules, metal-organic framework, carbon nanotubes, etc.) are addressed separately in the present literature. This review reveals the advantages and disadvantages of the techniques and materials for metal ion sensing with crucial factors. Furthermore, it focus on the capability of conjugated polymers (CPs) as metal ion sensors able to detect/sense hazardous metal ions from environmental samples. Six different routes can synthesize this type of CPs to get specific properties and better metal ion detecting capability in vast research areas. The metal ion detection by CP is time-independent, simple, and low cost compared to other materials/techniques. This review outlines recent literature on the conjugated polymer for cation, anion, and dual ion sensors. Over the last half decades published articles on the conjugated polymer are discussed and compared.

Treatment of vitiligo with 308-nm light emitting diode: Our experience from a two-year follow-up of Chinese patients

BACKGROUND

A light emitting diode (LED), with a wavelength of 308 nm, has been utilized in the dermatologic treatment of vitiligo.

OBJECTIVES

We investigated the efficacy and safety of 308-nm LED for use in the treatment of vitiligo.

METHODS

We conducted a retrospective study of 70 stable-stage vitiligo patients (with a total of 99 lesions) who received 308-nm LED treatment at the Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College from June 2018 to June 2020. Treatment efficacy was evaluated after 8 treatment sessions, 16 treatment sessions, and the final treatment session, to estimate the percentage of re-pigmentation in the treated area. The Kruskal-Wallis test was used for data analysis.

RESULTS

Based on the final treatment session analysis of all 99 lesions, 0 lesions showed no response, 21 lesions showed poor response, 29 lesions showed moderate response, 23 lesions showed good response, and 26 lesions showed excellent response. The efficacy rate was 49.49%, and there was a significant correlation between the six distinct anatomical regions treated and re-pigmentation grade (χ²  = 13.419, p = .009). Among these regions, facial lesions showed the best response to treatment, while the hands and feet lesions showed the poorest response.

CONCLUSIONS

The clinical efficacy of 308-nm LED treatment is limited based on the treatment area. It demonstrated significant practical application in the treatment of vitiligo.

Anterior-Segment Swept-Source Ocular Coherence Tomography and Scheimpflug Imaging Agreement for Keratometry and Pupil Measurements in Healthy Eyes

This study examines agreement between the devices Anterion^® and Pentacam HR^® used for corneal and pupil measurements in healthy eyes. The parameters compared between the two devices were: anterior Km (D), anterior K2 (D), anterior K1 (D), anterior K1 axis (°), anterior astigmatism (D), anterior K max (D), posterior Km (D), posterior K2 (D), posterior K1 (D), posterior K1 axis (°), posterior astigmatism (D), CCT (µm), thinnest point thickness (µm), thinnest point X-coordinate (mm), thinnest point Y-coordinate (mm), pupil diameter (mm), pupil center-corneal vertex distance (mm) (angle kappa), pupil centroid angle (°), pupil centroid X-coordinate (mm), and pupil centroid Y-coordinate (mm). The Student’s t test for independent samples identified significant differences (p < 0.005) between devices for the measurements anterior and posterior flat K axis, posterior flat K, steep K, and mean K. For these last three measurements, although significant, none of the differences were clinically relevant. Corneal power and thickness measurements except Kf axis showed excellent agreement between Anterion and Pentacam. In a clinical setting we would not recommend the interchangeable use of Pentacam and Anterion for measurement of pupil parameters.

Stable 2 W continuous-wave 261.5 nm laser for cooling and trapping aluminum monochloride

We present a high-power tunable deep-ultraviolet (DUV) laser that uses two consecutive cavity enhanced doubling stages with LBO and CLBO crystals to produce the fourth harmonic of an amplified homebuilt external cavity diode laser. The system generates up to 2.75 W of 261.5 nm laser light with a ∼2 W stable steady-state output power and performs second harmonic generation in a largely unexplored high intensity regime in CLBO for continuous wave DUV light. We use this laser to perform fluorescence spectroscopy on the A¹Π ← X¹Σ⁺ transition in a cold, slow beam of AlCl molecules and probe the A¹Π|v' = 0, J' = 1〉 state hyperfine structure for future laser cooling and trapping experiments. This work demonstrates that the production of tunable, watt-level DUV lasers is becoming routine for a variety of wavelength-specific applications in atomic, molecular and optical physics.

Laser Therapy for the Treatment of Morphea: A Systematic Review of Literature

Morphea, also known as localized scleroderma (LoS), comprises a set of autoimmune sclerotic skin diseases. It is characterized by inflammation and limited thickening and induration of the skin; however, in some cases, deeper tissues might also be involved. Although morphea is not considered a life-threatening disease, the apparent cosmetic disfigurement, functional or psychosocial impairment affects multiple fields of patients’ quality of life. Therapy for LoS is often unsatisfactory with numerous treatments that have only limited effectiveness or considerable side effects. Due to the advances in the application of lasers and their possible beneficial effects, the aim of this study is to review the reported usage of laser in morphea. We present a systematic review of available literature, performed with MEDLINE, Cinahl, Central, Scopus, Web of Science, and Google Scholar databases. We identified a total of twenty relevant studies (MEDLINE n = 10, Cinahl n = 1, Central n = 0, Scopus n = 2, Web of Science n = 5, Google Scholar n = 2) using laser therapy for LoS. Eight studies were focused on the use of PDL, six on fractional lasers (CO₂ and Er:YAG), four on excimer, and two on either alexandrite or Nd:YAG.

Engineered antigen-specific regulatory T cells for autoimmune skin conditions

Regulatory T cells (Tregs) are a subset of T cells responsible for the regulation of immune responses, thereby maintaining immune homeostasis and providing immune tolerance to both self and non-self-antigens. An increasing number of studies revealed Treg numbers and functions in a variety of autoimmune diseases. Treg deficiency can cause the development of several autoimmune skin diseases including vitiligo, alopecia areata, pemphigoid and pemphigus, psoriasis, and systemic sclerosis. Many clinical trials have been performed for autoimmune conditions using polyclonal Tregs, but efficiency can be significantly improved using antigen-specific Tregs engineered using T cell receptor (TCR) or chimeric antigen receptor (CAR) constructs. In this review, we systematically reviewed altered frequencies, impaired functions, and phenotypic features of Tregs in autoimmune skin conditions. We also summarized new advances in TCR and CAR based antigen-specific Tregs tested both in animal models and in clinics. The advantages and limitations of each approach were carefully discussed emphasizing possible clinical relevance to patients with autoimmune skin diseases. Moreover, we have reviewed potential approaches for engineering antigen-specific Tregs, and strategies for overcoming possible hurdles in clinical applications. Thereby, antigen-specific Tregs can be infused using autologous adoptive cell transfer to restore Treg numbers and to provide local immune tolerance for autoimmune skin disorders.

A deep dive into UV-based phototherapy: Mechanisms of action and emerging molecular targets in inflammation and cancer

UV-based phototherapy (including psoralen plus UVA (PUVA), UVB and UVA1) has a long, successful history in the management of numerous cutaneous disorders. Photoresponsive diseases are etiologically diverse, but most involve disturbances in local (and occasionally systemic) inflammatory cells and/or abnormalities in keratinocytes that trigger inflammation. UV-based phototherapy works by regulating the inflammatory component and inducing apoptosis of pathogenic cells. This results in a fascinating and complex network of simultaneous events-immediate transcriptional changes in keratinocytes, immune cells, and pigment cells; the emergence of apoptotic bodies; and the trafficking of antigen-presenting cells in skin-that quickly transform the microenvironment of UV-exposed skin. Molecular elements in this system of UV recognition and response include chromophores, metabolic byproducts, innate immune receptors, neurotransmitters and mediators such as chemokines and cytokines, antimicrobial peptides, and platelet activating factor (PAF) and PAF-like molecules that simultaneously shape the immunomodulatory effects of UV and their interplay with the microbiota of the skin and beyond. Phototherapy's key effects-proapoptotic, immunomodulatory, antipruritic, antifibrotic, propigmentary, and pro-prebiotic-promote clinical improvement in various skin diseases such as psoriasis, atopic dermatitis (AD), graft-versus-host disease (GvHD), vitiligo, scleroderma, and cutaneous T-cell lymphoma (CTCL) as well as prevention of polymorphic light eruption (PLE). As understanding of phototherapy improves, new therapies (UV- and non-UV-based) are being developed that will modify regulatory T-cells (Treg), interact with (resident) memory T-cells and /or utilize agonists and antagonists as well as antibodies targeting soluble molecules such as cytokines and chemokines, transcription factors, and a variety of membrane-associated receptors.

Thymol-Induced Chemical Leukoderma Successfully Treated with 308-Nanometer Excimer Laser

Introduction

Chemical leukoderma (CL) is an acquired depigmenting disorder caused by repeated exposure to chemical compounds. Thymol is a phenol derivative used as a preservative or antiseptic in many commercially available products. Here, we present the second reported case of CL caused by a thymol-containing compound.

Case Presentation

A 48-year-old woman presented with a 4-month history of depigmentation of the nail folds of all ten fingers. This occurred after 1 month of twice-daily application of a thymol-containing compound intended for the removal of gel nails. No improvement was noted after the product was discontinued. There was no family history of vitiligo or other autoimmune disorders. On physical exam, depigmentation of all ten proximal and lateral nail folds was seen, with accentuation on Wood's lamp exam. Partial re-pigmentation was achieved after 32 treatments with 308-nm excimer laser.

Discussion

A thorough history and physical exam are instrumental in differentiating CL from other causes of depigmentation. Avoidance of the offending agent is an essential part of management. It is important to note that many cosmetic products are not tightly regulated by the FDA. Excimer laser is an effective treatment for CL with a favorable side-effect profile.

Beyond the Booth: Excimer Laser for Cutaneous Conditions

The excimer laser has emerged as an efficacious treatment modality for many dermatologic diseases. The excimer laser is an alternative to standard narrowband ultraviolet B (NBUVB) phototherapy treatment in patients with limited disease. In comparison to standard NBUVB, the excimer laser requires fewer treatment sessions, has reduced treatment duration, requires a lower cumulative UVB dose, and limits UVB exposure to lesional skin. This review addresses the mechanism, safety, application, and efficacy of the excimer laser for the treatment of these conditions.

A combination of Yiqiqubai granule and 308-nm excimer laser in treatment of segmental vitiligo: a prospective study of 233 patients

OBJECTIVE

To study the effect of Yiqiqubai granule combined with 308-nm excimer laser treatment for segmental vitiligo (SV).

METHODS

A prospective research was performed in 233 patients with SV treated in Shanghai General Hospital from 11 February 2015 to 25 August 2016, they were divided into group A (n = 75), group B (n = 78) and group C (n = 80) according to the random number table. Group A was treated with Yiqiqubai granule, group B treated with 308-nm excimer laser and group C treated with combined treatments. The treatment time lasts for 6 months. The clinical efficacy, color-reverse rate and quality of life of the three groups were assessed.

RESULTS

After treatment, the effective rate and markedly effective rate of group C (87.5%, 51.3%) were significantly higher than group A (74.7%, 42.7%) and group B (80.8%, 47.4%) (p < .05). Color-reverse rate of group C (66.5 ± 17.6%) was much higher than group A (47.2 ± 16.4%) and group B (49.9 ± 24.2%) (p < .05). Significant differences were found among three groups after treatment in terms of embarrassment, social and work (p < .05).

CONCLUSIONS

The combination of 308-nm excimer laser and Yiqiqubai granule in the treatment of SV has good clinical effect.

Excimer laser for the treatment of psoriasis: safety, efficacy, and patient acceptability

Introduction

The 308 nm excimer laser is a widely used device throughout the field of dermatology for many diseases including psoriasis. Although the laser has demonstrated clinical efficacy, there is a lack of literature outlining the safety, efficacy, and patient acceptability of the excimer laser.

Methods

A literature search on PubMed was used with combinations of the terms “excimer”, “excimer laser”, “308 nm”, “psoriasis”, “protocol”, “safety”, “efficacy”, acceptability”, “side effects”, and “dose”. The search results were included if they contained information pertaining to excimer laser and psoriasis treatment and description of the safety, efficacy, and patient acceptability of the treatment.

Results

The 308 nm excimer laser is generally safe and well tolerated with minimal side effects including erythema, blistering, and pigmentary changes. It has a range of efficacies depending on the protocol used with several different treatment protocols, including the induration protocol, the minimal erythema dose protocol, and the newer minimal blistering dose protocol.

Conclusion

Although the excimer laser is not a first-line treatment, it remains an excellent treatment option for psoriasis patients and has been demonstrated to be an effective treatment with little to no side effects.

Freeform microlens array homogenizer for excimer laser beam shaping

We presented a novel technique to design microlens optical beam homogenizing system for excimer lasers. As a new approach by applying freeform surface microlens array, the homogenizer can yield somehow superior beam shaping results with larger but less microlens units than conventional method. With new concept and design, the diffraction effects at the microlens apertures can be reduced substantially. Large scale and highly uniform beam profile can be realized at a relative nearby working distance after beam shaping. This is hard to achieve by conventional method. Our design method takes the real spatial energy characteristics of the excimer laser beam as the design basis, and combined with feasible optimization method. The design method is demonstrated as a real instance based, on a 193 nm ArF excimer laser in our laboratory. Moreover, to verify the effectiveness of our method, the designed freeform microlens array homogenizer has been fabricated and tested experimentally. The experimental optical performance of the homogenizer coincides well with the theoretical simulation.