Medical Laser Research Articles

Analysis of the Effect of Nd:YAG Laser Irradiation on Soft Tissues of the Oral Cavity in Different Modes in an In Vivo Experiment

The development of laser medicine has led to its use in dentistry further to improve existing treatment methods, including surgical techniques. The variety of lasers allows them to be used for procedures on the soft and bone tissues of the oral cavity as well as on the tissues of the teeth. The short duration of laser pulse action on tissues, selective action on pathological tissues in a sterile surgical field, and activation of local and humoral immunity of the oral cavity provides an increase in the regeneration potential of tissues of the postoperative area, which contributes to the shortening of wound process phases, favorable course of the postoperative period, and shortening of the healing time. Our article presents the experience of using the Nd:YAG laser in different modes in replicating the effect of curettage of periodontal pockets in an experiment on laboratory animals. According to the study results, there was a difference in the healing time of soft tissues after their exposure to several modes of the Nd:YAG laser, which makes it possible to recommend each of them for individual clinical cases.

A Micron-Sized Laser Photothermal Effect Evaluation System and Method.

The photothermal effects of lasers have played an important role in both medical laser applications and the development of cochlear implants with optical stimulation. However, there are few methods to evaluate the thermal effect of micron-sized laser spots interacting with other tissues. Here, we present a multi-wavelength micro-scale laser thermal effect measuring system that has high temporal, spatial and temperature resolutions, and can quantitatively realize evaluations in real time. In this system, with accurate 3D positioning and flexible pulsed laser parameter adjustments, groups of temperature changes are systematically measured when the micron-sized laser spots from six kinds of wavelengths individually irradiate the Pd/Cr thermocouple junction area, and reference data of laser spot thermal effects are obtained. This work develops a stable, reliable and universal tool for quantitatively exploring the thermal effect of micron-sized lasers, and provides basic reference data for research on light-stimulated neuron excitement in the future.

The 42<sup>nd</sup> Annual Meeting of Japan Society for Laser Surgery and Medicine—Laser Week in Tokyo II—

The 42<sup>nd</sup> Annual Meeting of Japan Society for Laser Surgery and Medicine—Laser Week in Tokyo II—

Modern concepts of erythematotelangiectatic rosacea pathogenesis and treatment

Rosacea is a multifactorial chronic pathology characterized by a complex etiopathogenesis. Rosacea is represented by 4 subtypes: erythematotelangiectatic, papulopustular, rhinophyma and ophthalmic rosacea.
 Clinical manifestations of erythematotelangiectatic rosacea reduce the quality of human life, which is manifested by disorders of the psychoemotional sphere of varying severity. The erythematotelangiectatic subtype is influenced by two groups of trigger factors ― internal and external.
 Mandatory areas of patients management with rosacea in general include the triad of treatment: providing proper skin care, health education, a set of therapeutic measures.
 Rosacea drug therapy is divided into local and systemic. The main treatment for erythematotelangiectatic rosacea is to eliminate the vascular component and reduce the severity of transient and persistent erythema.
 Among the physiotherapeutic methods, the most promising today are considered to be laser therapy and an intense pulsed light system (IPL). The effectiveness of laser medicine in dermatology is due to the ability to selectively build up the laser of the chromophochic layer of the dermis. The mechanism of action of IPL-therapy is associated with the absorption of photons by internal or external chromophores, which are located in different layers of the skin, which can locally increase the temperature and cause destructed target formations.
 A review of the literature on pathogenesis, trigger factors, classification and modern treatment of eerythematotelangiectatic rosacea is based on an analysis of articles on the relevant topic 44 presented in information systems electronic library, PubMed, NCBI, Embase. Studies are described demonstrating the convincing effectiveness of the treatment of patients with lasers and the IPL system.

Long-term outcomes of PRK, LASIK and SMILE

Patients and refractive surgeons have alegitimate interest in the long-term results of the most commonly used laser procedures for correction of ametropia. To assess the safety, predictability, stability and late complications according to the current recommendations of the committee for refractive surgery (KRC). Literature search in PubMed with the search term "long-term outcome" combined with either "PRK", "LASIK" or "SMILE". Articles about PRK and LASIK with aminimum follow-up of 10years and SMILE with aminimum follow-up of 5years were evaluated and duplications were eliminated. From atotal of 440 articles that matched these search terms 15articles were selected and analyzed. The results of PRK were described in 4 studies with atotal of 666 eyes, 7 studies (566 eyes) described the results of LASIK and 5 studies (188 eyes) the results after SMILE. Long-term studies with follow-up periods of at least 10 years have shown that PRK and LASIK treatment carried out in the early days of medical excimer lasers have avery high level of safety and late complications occurred only rarely. The effectiveness of particularly high corrections declined over time. In contrast, there was no clinically significant regression within the indications recommended by the KRC. The results of SMILE were not inferior to those of PRK and LASIK. In direct long-term comparisons no procedure showed aclear superiority. Due to technological improvements in hardware and software for both preoperative diagnostics and lasers, treatment performed nowadays is presumably even safer, more efficient and also more stable over along period of time.

Safe Use of Medical Lasers

Safe Use of Medical Lasers

Towards personalized and versatile monitoring of temperature fields within heterogeneous tissues during laser therapies.

Advancements in medical laser technology have paved the way for its widespread acceptance in a variety of treatments and procedures. Selectively targeting particular tissue structures with minimally invasive procedures limits the damage to surrounding tissue and allows for reduced post-procedural downtime. In many treatments that are hyperthermia-based, the efficiency depends on the achieved temperature within the targeted tissues. Current approaches for monitoring subdermal temperature distributions are either invasive, complex, or offer inadequate spatial resolution. Numerical studies are often therapy-tailored and source tissue parameters from the literature, lacking versatility and a tissue-specific approach. Here, we show a protocol that estimates the temperature distribution within the tissue based on a thermographic recording of its surface temperature evolution. It couples a time-dependent matching algorithm and thermal-diffusion-based model, while recognizing tissue-specific characteristics yielded by a fast calibration process. The protocol was employed during hyperthermic laser treatment performed ex-vivo on a heterogeneous porcine tissue, and in-vivo on a human subject. In both cases the calibrated thermal parameters correlate with the range of values reported by other studies. The matching algorithm sufficiently reproduced the temperature dynamics of heterogeneous tissue. The estimated temperature distributions within ex-vivo tissue were validated by simultaneous reference measurements, and the ones estimated in-vivo reveal a distribution trend that correlates well with similar studies. The presented method is versatile, supported by the protocol for tissue-specific tailoring, and can readily be implemented for temperature monitoring of various hyperthermia-based procedures by means of recording the surface temperature evolution with a miniature thermal camera implemented within a handheld laser scanner or similar.

Three Inspiring Review Articles on Photobiomodulation: Update 2021

Photobiomodulation (PBM) is an accurate term for an effective and important application of light in medicine (such as in photomedicine). Three review articles of authors from the International Society of Medical Laser Applications (ISLA-Transcontinental) on the topic of PBM with a total of 116 printed pages, published in one renowned journal of molecular sciences with an impact factor of 13.668, are presented in the current review. The main topics are PBM, probiotics, curcumin, and arthritis. PBM can modulate cellular dysfunctions, trigger self-organization phenomena, and alleviate different diseases.

The first experience of applying laser ablation in patients with benign tumors, tumor-like and inflammatory diseases of the skeleton

The researchers discuss the first experience of treating 9 pediatric patients with osteoid osteoma (3), primary chronic osteomyelitis (4) and aneurysmal cysts (2). Selected patients had complex treatment which included unloading of the diseased segment of the skeleton and laser ablation of the pathological focus. Laser ablation was done with medical laser «AZOR-ALM», emitting light at wavelength 1.55 μm. Registration certificate No. RZN 2015/2720 of Roszdravnadzor. Manufacturer – LLC «AZOR» (Moscow). Small tumors and inflammatory diseases of the skeleton were surgically treated with high-level laser light in the computed tomography room. Patients with lesions of lower extremities and pelvis previously had spinal anesthesia. If a pathologic focus was located in bones of upper extremities, regional brachial plexus blockage was preferable. In all cases, positive outcomes were seen. Follow-up lasted for 6 months.

Histological Ex Vivo Evaluation of the Suitability of a 976 nm Diode Laser in Oral Soft Tissue Biopsies.

Introduction Laser-induced thermal effects can preclude a safe histological evaluation of biopsy resection margins. The aim of this study was to evaluate the suitability of a 976 nm diode laser in oral soft tissue biopsies in an ex vivo study. Materials and Methods A 976 nm diode laser (Solase®, Lazon Medical Laser, China) has been used in the contact mode, using a 400 μm fiber tip, at different parameters from 4 to 6 W in the continuous wave (CW), with a fluence between 3184 and 4777 J/cm2, and pulsed wave (PW) mode, with a fluence between 318,4 and 477,7 J/cm2, to obtain 30 samples from fresh pig cadaver tongues. All specimens were subdivided into 6 groups (from A to F), and each group consisted of 5 samples. Two sections were obtained from each sample. A histological analysis was performed using an optical microscope at magnifications of 5x and 10x. Statistical analysis was carried out using Kruskal–Wallis and Dunn's tests. Results The results showed that histological readability was optimal in all the samples. The thermal damage was negligible in all groups. The average thermal damage was 208.40 ± 133.81 μm in the epithelial tissue and 330.14 ± 147.45 μm in the connective tissue. The statistical analysis showed no differences between the groups (p > 0.05). Conclusion A 976 nm diode laser demonstrated good surgical effectiveness that provoked little peripheral damage in the cut edges and allowed a safe histological diagnosis. Clinical Relevance. In oral pathology, many times, there is fear in using the laser to remove some lesions due to its thermal effect on the tissues close to the lesion. This effect is always present in the use of the laser, but the intent is to minimize this effect to have as little alteration as possible on the surrounding tissues.

Pigment Dispersion Syndrome

Pigment dispersion syndrome (PDS) is a disorder predominantly affecting young, myopic adults. It is characterised by the liberation of pigment of the iris and deposition of it on various structures of the anterior segment leading to multiple specific findings in slit lamp examination. Typical alterations are a deposition of pigment on the central corneal endothelium, circular iris transillumination defects in the mid periphery, a posterior bowing of the iris and increased pigmentation of the trabecular meshwork. Findings are usually bilateral symmetric. Posterior bowing of the iris causes rubbing of the pigmented iris epithelium against lens structures like zonular fibres with a consecutive liberation of pigment. Trabecular meshwork changes because of pigment deposition reduce aqueous outflow facility with the risk of elevated intraocular pressure and glaucoma. Pigmentary glaucoma (PG) is a secondary open angle glaucoma. Treatment of PG is similar to primary open angle glaucoma, including medical therapy, laser therapy and surgery. Peripheral laser iridotomy was shown to change iris configuration but its efficacy in the prevention of PG has not been confirmed in the literature. The purpose of this paper is to summarize information regarding ocular manifestations of PDS to facilitate an early diagnosis and to present a general view of the treatment of PG.

The 42<sup>nd</sup> Annual Meeting of Japan Society for Laser Surgery and Medicine—Laser Week in Tokyo II—

The 42<sup>nd</sup> Annual Meeting of Japan Society for Laser Surgery and Medicine—Laser Week in Tokyo II—

622 Enhanced Recovery After Surgery for Fractional CO2 Laser Treatment of Burn Scars

Abstract Introduction Healthcare systems have adopted enhanced recovery after surgery (ERAS) programs as evidence-based, multimodal, and multidisciplinary perioperative approaches to mitigate complications and improve early recovery. ERAS programs modify psychological and physiological response to surgery with standardized care pathways that range from preoperative assessment and education through pharmacologic and surgical interventions. Our study demonstrates a burn scar specific ERAS protocol with pre- and post- intervention outcomes. Methods As part of a quality and performance improvement initiative, a multidisciplinary panel at an ABA-verified burn center consisting of burn nurses, burn surgeons, burn physician assistants, burn therapist, clinical pharmacist, certified medical laser safety officer, and anesthesiologist reviewed the available literature regarding pain, laser treatments, and medication histories of prior fractional CO2 laser treatments. The ERAS program was designed with preoperative, perioperative, and postoperative interventions to reduce pain and complications defined as unscheduled visits/admission to the ER or burn center, narcotic administration >1 hour post procedure, or wound complications secondary to laser treatment requiring dressing changes >1 week post-procedure. Quality and performance metrics were collected as a component of the burn registry program and reviewed twice monthly. The ERAS protocol preoperative phase included standardization of outpatient screening, assessment, and electronic medical record documentation. The perioperative phase included standardization of preprocedural medications including multimodal analgesia. The intraoperative phase included standardization of medications and dressing application. Post procedural phase included standardized instructions for wound care and follow-up. Results Pre-implementation complications over a three-month period included one patient requiring wound care >1 week post laser treatment and 4 patients requiring narcotic administration >1 hour post procedure (16% of laser cases). Post-implementation of the ERAS program no complications were identified in 62 cases over a three-month period. Conclusions At our institution a burn scar specific ERAS protocol reduced perioperative complications following fractional CO2 laser procedures. While many opportunities exist to improve scarring and pain, the multidisciplinary approach in burn care is as essential for outpatients as it is for inpatients at reducing avoidable complications.

Efficient monolithic diamond Raman yellow laser at 572.5 nm

A high-power Raman yellow laser with a wavelength of 572.5 nm is demonstrated. High-power Raman laser is always restricted by various thermal effects inside the Raman crystals. Based on the theoretical analyze about the thermal effects, the internal heat accumulation can be slightly adjusted by output transmittances. Yellow laser is achieved with the average output power of 9.2 W and the slope efficiency of 60.8%, used a monolithic diamond crystal, with high thermal conductivity, as the Raman medium. The corresponding results have impacts on promoting the application of yellow laser into the fields of medical treatment, laser display, and scientific investigation. • A high-power Raman yellow laser is demonstrated based on a monolithic diamond micro-cavity at wavelength of 572.5 nm. • Based on the theoretical analyze about the thermal effects, the internal heat accumulation can be slightly alleviated by optimizing output transmittances. • Yellow laser is achieved with the average output power of 9.2 W and the slope efficiency of 60.8%.

Educational and scholarly opportunities for medical students and residents in the United States dermatology societies

Educational and scholarly opportunities for medical students and residents in the United States dermatology societies

Engineering controls for surgical smoke in laser medical handpieces

The hazard of surgical smoke is often overlooked when considering the safety of medical laser procedures but can present a high level of occupational risk. Administrative procedures for operating external extraction devices and the reliance on personal protective equipment are not sufficient for reducing the risk. This paper aims to quantify the hazard of laser-generated surgical smoke and demonstrate how effective engineering control solutions can reduce the risk. A new design solution is presented with engineering controls for surgical smoke extraction and optical radiation integrated into the laser handpiece. A fiber delivered diode laser is used to simulate laser vaporization procedures on porcine skin tissue. Conventional external extraction conditions are compared to the new design solution. Fine particulate mass concentrations (PM2.5) from the simulated procedures, under different extraction conditions, are measured using optical particle size measurements. Peak concentrations of 55.86 ± 2.79 μg/m3 were measured without extraction; showing that the hazard of laser-generated surgical smoke is five times greater than the World Health Organization guideline of 10 μg/m3. A typical medical extraction setup only achieved a 16% reduction in peak concentration values, 47.07 ± 2.35 μg/m3; demonstrating that conventional, external, methods of extraction are ineffective. The new solution was able to capture all particulate materials, reducing particulate concentrations to background levels, 2.19 ± 0.68 μg/m3, safely below the current recommended guidelines. The design and results present evidence that it is not only more effective to use engineering control methods but that it is practicable to do so.

Optical investigation of bovine grey and white matters in visible and near-infrared ranges

Abstract Introduction: Due to enormous interests for laser in medicine and biology, optical properties characterization of different tissue have be affecting in development processes. In addition, the optical properties of biological tissues could be influenced by storage methods. Thus, optical properties of bovine white and grey tissues preserved by formalin have been characterized over a wide wavelength spectrum varied between 440 nm and 1000 nm. Materials and Methods: To that end, a single integrating sphere system was assembled for spectroscopic characterization and an inverse adding-doubling algorithm was used to retrieve optical coefficients, i.e. reduced scattering and absorption coefficients. Results: White matter has shown a strong scattering property in comparison to grey matter. On the other hand, the grey matter has absorbed light extensively. In comparison, the reduced scattering profile for both tissue types turned out to be consistent with prior works that characterized optical coefficients in vivo. On the contrary, absorption coefficient behavior has a different feature. Conclusion: Formalin could change the tissue’s optical properties because of the alteration of tissue’s structure and components. The absence of hemoglobin that seeps out due to the use of a formalin could reduce the absorption coefficient over the visible range. Both the water replacement by formalin could reduce the refractive index of a stored tissue and the absence of hemoglobin that scatters light over the presented wavelength range should diminish the reduced scattering coefficients over that wavelength range.

Scattering Properties of an Optical Fiber with a Silica Light-Conducting Core and a Light-Reflecting Shell Fabricated from a Fluorinated Thermoplastic Polymer

The scattering properties of an optical fiber with a silica light-conducting core and a light-reflecting shell made of a fluorinated thermoplastic copolymer of tetrafluoroethylene with Tefzel ethylene have been experimentally studied. It is established that when radiation (λ = 532 nm) propagates along this fiber, a noticeable scattering of the evanescent part of the wave propagating along the reflective shell is observed. The shell scattering indicatrix, the distribution of the scattered radiation intensity along the fiber axis, and its dependence on the conditions of radiation input into the optical fiber were measured. The total scattered radiation is calculated and compared with the radiation transmitted through an optical fiber. The possibility of using these optical fibers in laser medicine is discussed.

Plume control in medical and cosmetic laser clinics: a practical guide

In this article, Godfrey Town and Mike Murphy review risk assessments that aim to control the dangers of plume and make recommendations that laser specialists can use to make their practice safe and secure

Synthesis of the AgBr – AgI system optical crystals

Abstract The presented work is devoted to the study and development of the technology for obtaining the AgBr – AgI crystals system. Studies have been carried out to study the phase diagram in order to clarify the region of stable solid solutions' existence. Based on the data obtained, the modes were selected and single crystals of various compositions were synthesized. Their main optical properties, such as the spectral transmission range, were investigated and the refractive indices were determined at the wavelength of the short-wave absorption edge and the CO2 laser (10.6 μm). The work’ results are necessary for the manufacture of various structures IR fibers, windows, lenses, and other optical products, which are widely used in different fields of science and technology, including laser, endoscopic, and diagnostic medicine.