Excimer Laser Applications Research Articles

Use of In Vivo Corneal Confocal Microscopy to Guide Excimer Laser With Adjunctive Mitomycin C for Treatment of Recalcitrant Acanthamoeba Keratitis.

The aim of this study was to describe 3 cases of recalcitrant Acanthamoeba keratitis (AK) that were successfully treated using in vivo corneal confocal microscopy (IVCM) to guide excimer laser ablation depth with adjunctive mitomycin C 0.02%. Three patients diagnosed with AK did not respond to several weeks of intensive topical therapy with antiamoebic agents. The patient underwent phototherapeutic keratectomy with topical mitomycin C 0.02% application. The maximum stromal depth of cysts measured by IVCM was 80 μm, 100 μm, and 240 μm, and the stromal ablation depths were 80 μm, 100 μm, and 100 μm, respectively. In all 3 eyes, AK resolved after a single excimer laser application, and topical treatment was gradually discontinued within 6 weeks afterward. In 1 eye, penetrating corneal transplantation was performed 6 weeks after phototherapeutic keratectomy because of ongoing severe corneal pain. IVCM and histology of the corneal transplant did not reveal any Acanthamoeba cysts within the excised corneal button. No recurrence was observed during the follow-up period of 19 to 34 months. IVCM-guided phototherapeutic keratectomy with mitomycin C 0.02% seems to be a safe and successful approach for the treatment of AK, especially in cases of resistance to topical treatment. Corneal IVCM should be performed before laser application to measure cyst depth, determine ablation depth, and assess postoperative treatment success.

Excimer Laser 308 nm

ABSTRACT The excimer laser delivers targeted ultraviolet radiation at 308 nm, useful for delivering targeted phototherapy. It can also be useful in treating difficult-to-reach treatment sites while minimizing radiation exposure to surrounding skin. The excimer laser has been FDA approved for treatment of inflammatory skin conditions. This review summarizes excimer laser applications and advantages over other narrowband UVB and other phototherapy treatments.

Discharge-Pumped Excimer Laser Technologies and Applications

Discharge-Pumped Excimer Laser Technologies and Applications

High-Current Operation of Racetrack-Shaped LTD Using SiC-MOSFETs for Pulsed Laser Applications

Pulsed power is widely used for the excitation of pulsed lasers, especially the ultraviolet excimer lasers. Experiments have been carried out to demonstrate the excitation of KrF excimer laser by using pulsed power generator based on linear transformer driver (LTD) <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . In this article, the LTD system has been upgraded by replacing the semiconductor switches with silicon carbide (SiC) devices in order to increase the output current and by reshaping the output interface so that it fits better with the geometry of the laser chamber. For excimer laser application, the output current and its rise time are very important issues. These are the focus points of the system design and performance analysis for this study. The experimental test system is described in detail and the results are presented with discussions on potential applications.

Cold Laser Micro-Machining of PDMS as an Encapsulation Layer for Soft Implantable Neural Interface.

PDMS (polydimethylsiloxane) is an important soft biocompatible material, which has various applications such as an implantable neural interface, a microfluidic chip, a wearable brain–computer interface, etc. However, the selective removal of the PDMS encapsulation layer is still a big challenge due to its chemical inertness and soft mechanical properties. Here, we use an excimer laser as a cold micro-machining tool for the precise removal of the PDMS encapsulation layer which can expose the electrode sites in an implantable neural interface. This study investigated and optimized the effect of excimer laser cutting parameters on the electrochemical impedance of a neural electrode by using orthogonal experiment design. Electrochemical impedance at the representative frequencies is discussed, which helps to construct the equivalent circuit model. Furthermore, the parameters of the equivalent circuit model are fitted, which reveals details about the electrochemical property of neural electrode using PDMS as an encapsulation layer. Our experimental findings suggest the promising application of excimer lasers in the micro-machining of implantable neural interface.

Key Technologies and Applications of Excimer Laser as Light Sources in Lithography

Key Technologies and Applications of Excimer Laser as Light Sources in Lithography

Thought of corneal collagen cross-linking combined with excimer laser ablation for irregular corneas in keratoconus

The concept of diagnosis and treatment of keratoconus is constantly updated. Today, we are not only concerned with how to delay the progress of the disease, but also with the preservation of useful vision for patients as well as improvement of visual quality. With the precise and individualized application of excimer laser and femtosecond laser technology in ophthalmology, corneal cross-linking combined with excimer laser ablation for the irregular cornea has become a new strategy for keratoconus. However, questions have been raised and caused ophthalmologists' thinking. Are patients with keratoconus who have progressively thinned corneas suitable for excimer laser ablation? Which is better when the combined strategy is applied, simultaneous or sequential surgery? Based on the research data from home and abroad, we comprehensively sort out various treatment methods for the focus issues. It is hoped that this article can provide guidance for the rational selection of an optimal clinical solution to keratoconus. (Chin J Ophthalmol, 2021, 57:251-253).

Comparison of effects of mydriatic drops (1% cyclopentolate and 0.5% tropicamide) on anterior segment parameters.

Purpose:The purpose of this study is to investigate and compare the effects of cyclopentolate and tropicamide drops on anterior segment parameters in healthy individuals.Methods:Two hundred and fifty-eight eyes of 129 healthy volunteers were included in this randomized clinical study. Cyclopentolate 1% drop was applied to 75 (58%) participants (group 1) and tropicamide 0.5% drop was applied to 54 (42%) participants (group 2). Flat keratometry (K1), steep keratometry (K2), axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), white-to-white (WTW) distance, pupil diameter, total pupil offset and intraocular lens (IOL) power were measured before and after drops, using Lenstar 900 optical biometry.Results:The increase in CCT, ACD, pupil diameter, and pupil offset was significant in group 1 after the drop (P < 0.05), while the increase in ACD, pupil diameter, and pupil offset was significant in group 2 (P < 0.05). When the two groups were compared, there was no significant difference in K1, K2, CCT, ACD, WTW, pupil diameter, pupil offset, and IOL power (using Sanders–Retzlaff–Kraff T formula) changes after drops (P > 0.05), whereas the change in AL was significant (P = 0.01).Conclusion:The effects of cyclopentolate and tropicamide drops on anterior segment parameters were similar; they did not make significant changes in K1, K2, AL, WTW, and third-generation IOL power calculation. However, ACD values significantly changed after these drops; thus, measuring anterior segment parameters before mydriatic agents should be taken into account particularly for fourth-generation IOL formulas and phakic IOL implantation. The change in pupil offset, which can be important in excimer laser and multifocal IOL applications, was not clinically significant.

Experimental Rationale for Using an Eximer Laser for Preparation of Ultrathin Graft for Posterior Lamellar Keratoplasty

Purpose. To rationale experimentally the use of an excimer laser for forming an ultrathin transplant for posterior lamellar keratoplasty. Materials and methods. Atomic force microscopy was used for examination of 10 samples. Control group was 5 corneal flaps obtained by mechanical microkeratome (Moria SLK-2, France). Main group — 5 corneal flaps, obtained by microkeratome and underwent photoablation by “Microscan 500” (Optosystems, Troick, RF) excimer laser at 50 um depth. For quantification of endothelial loss 10 donor corneas (5 pairs) with viable endothelium, preserved in Borzenok—Moroz media, were used. Two groups were formed: main — 5 ultrathin transplants obtained by consistent application of microkeratome and excimer laser, control (from the paired eyes of same donors) — ultrathin transplants prepared by two cuts of microkeratome. Detection of live and dead endothelial cells (EC) was provided by Calcein Violet 450 and Propidium Iodide “vital” fluorescent dyes. Nonparametric Mann—Whitney test was used for statistical analysis. Coefficient of reliability (p &lt; 0.05) was considered to be significant. Results. RMS (roughnessmean square) of the transplant, prepared by excimer laser was — 24.17 ± 12.4 um, and RMS of the transplant prepared by microkeratome — 22.3 ± 18.3 um. Statistical analysis did not reveal significant differences in RMS values in the mentioned groups (p &gt; 0.05). EC death in excimer laser group was 10.35 ± 5.84 %. EC death in microkeratome group — 8.06 ± 1.31 %. No statistically reliable difference of EC death was revealed in the 2 groups (p &gt; 0.05). Conclusions. The investigation has showed identical RMS values in the examined groups, representing high optical qualities of the transplant prepared by excimer laser. EC loss was also comparable in 2 groups. The received results indicate considerable potential of excimer laser transplants for posterior lamellar keratoplasty.

CIRCLE Enhancement After Myopic SMILE.

To report the outcomes of enhancement after small incision lenticule extraction (SMILE) using the VisuMax CIRCLE option (Carl Zeiss Meditec AG, Jena, Germany), which converts the SMILE cap into a femtosecond LASIK flap for secondary excimer laser application. Of 2,065 SMILE procedures, 22 eyes (1.1%) re-treated with CIRCLE with a follow-up of 3 months were included in the analysis. SMILE was performed in the usual manner. For re-treatment, the CIRCLE procedure was performed with pattern D flap creation on the VisuMax system and subsequent excimer laser ablation with a Zeiss MEL 90 laser (Carl Zeiss Meditec) with plano target in all cases. Spherical equivalent was -5.56 ± 2.22 diopters (D) before SMILE and -0.51 ± 1.08 D before CIRCLE. CIRCLE enhancement was performed after a mean of 10.0 ± 7.9 months, allowed for safe flap lifting in all eyes, and resulted in a final manifest refraction spherical equivalent of 0.18 ± 0.31 D at 3 months (P < .008). The number of eyes within 0.50 and 1.00 D from target refraction increased from 31.8% to 90.9% and from 77.3% to 100%, respectively. Mean uncorrected distance visual acuity (UDVA) had already improved from 0.37 ± 0.16 to 0.08 ± 0.16 logMAR at 1 week (P < .0001), resulting in 0.03 ± 0.07 logMAR at 3 months (P < .0001). All eyes gained at least one line of UDVA. Corrected distance visual acuity (CDVA) remained unchanged at all time points (before vs after CIRCLE, P = .40). Two eyes (9.1 %) lost one line of CDVA; no eye lost two or more lines. The safety and efficacy indices were 1.03 and 0.97 at 3 months. The CIRCLE procedure represents an effective re-treatment option after SMILE. Compared to surface ablation re-treatment after SMILE, CIRCLE seems to offer advantages in respect to speed of visual recovery, safety, and predictability, but at the price of flap creation. [J Refract Surg. 2018;34(5):304-309.].

Advocating standardization and customization of corneal refractive surgery in Chinese domestic situation

With the improvement and application of excimer laser and femtosecond laser equipment in clinical ophthalmology, the diversified strategies for corneal refractive surgery candidates have been provided. Based on the trend of " all-laser treatment", it is very necessary to take the domestic situation into consideration when a standard and customized choice is made according to the indications of each specific surgical type. The characteristics and limitations of various surgeries are elucidated and commented here in order to provide some reasonable treatment options for refractive surgery. (Chin J Ophthalmol, 2016, 52: 481-485).

Applications of the Excimer Laser: A Review.

The 308-nm excimer laser has been approved by the Food and Drug Administration for the treatment of psoriasis and vitiligo. Its ability to treat localized areas has led to many studies determining its potential in the treatment of focal diseases with inflammation or hypopigmentation. To review the different applications of the 308-nm excimer laser for treating dermatologic conditions. An extensive literature review was conducted by searching PubMed, MEDLINE, and ClinicalKey to find articles pertaining to dermatologic conditions treated with the 308-nm excimer laser. Articles published that contributed to new applications of the excimer laser were included, as well as initial studies utilizing the excimer laser. The outcomes and results were compiled for different dermatologic conditions treated with the excimer laser. The 308-nm excimer laser has a wide range of uses for focal inflammatory and hypopigmented conditions. Treatment is generally well tolerated, with few adverse reactions. Larger studies and studies evaluating the long-term effects of the 308-nm excimer laser are needed.

Management of Keratoconus: Recent Trends

Keratoconus is a bilateral, progressive disease characterised by corneal thinning, ectasia, variable degree of irregular astigmatism and resultant mild to severe reduction in visual acuity. Multiple advances in corneal imaging and topographic mapping have led to a better understanding of the disease and its progression. Traditionally, use of spectacles and rigid contact lenses has been the primary mode of treatment in early KC while keratoplasty has been the treatment of choice in advanced cases. However, development of an array of therapeutic options over the last decade has revolutionized the approach to this disease. The preferred treatment for progressive KC has shown a paradigm shift from contact lens fitting for as long as tolerated, followed by Penetrating Keratoplasty (PK) or Deep anterior lamellar keratoplasty (DALK), to Ultraviolet-A (UV-A) induced collagen cross-linking (CXL) to stabilize corneal ectasia in the long term. Recently, use of Intrastromal Corneal Ring Segments, Phakic IOLs, application of excimer laser and use of combination techniques have all made significant contribution in providing options for effective management of different stages of this disease. Bowman layer (BL) transplantation is a new technique that has recently been introduced as an alternative to PK/ DALK in eyes with advanced KC, unsuitable for either UV-CXL or ICRS. By means of this article, we aim to provide a summary of these recent trends in therapeutic options for the optimal management of keratoconus.

Optic fiber sensors fabricated by laser-micromachining

Recent progress in using excimer and femtosecond lasers to fabricate functional fiber-optic sensing devices is reviewed extensively in this paper. The application of femtosecond lasers is to fabricate fiber gratings and in-line fiber-optic interferometers for measurements of strain, temperature and refractive index. The application of 157nm excimer lasers is to create fiber gratings and in-line fiber interferometers for measurements of strain, acceleration, pressure, temperature and refractive index. Compared with conventional optical fiber sensors, these novel micro optical fiber sensors fabricated by laser-micromachining have outstanding advantages, such as fast and direct formation, easy mass-production with ultralow-cost, good reproducibility, excellent optical performance, low temperature cross-sensitivity, etc., which pave a way to form a new generation of miniature fiber-optic sensors for many applications.

Current interventional coronary applications of excimer laser

Excimer laser utilization as an adjunctive device for percutaneous coronary intervention has increased in the last few years. Many technical advancements have led to better results in terms of efficacy and safety with a low complication rate. In particular, excimer laser for thrombus-containing lesions is able to achieve rapid thrombus removal and plaque debulking along with subsequent facilitation of stent angioplasty and a low rate of microvascular obstruction. Other indications for laser angioplasty embrace in-stent restenosis, chronic total occlusions, saphenous vein graft lesions and new potential applications, such as stent expansion optimization and bifurcation lesions. As for other medical devices, however, excimer laser should be tested in future randomized studies against current standard of therapy in order to better define its role for each of the indications summarized above.

Therapeutische Excimerlaserchirurgie der Hornhaut

Concomitant with new innovations in the field of refractive surgery, therapeutic excimer laser applications like phototherapeutic keratectomy (PTK) and topography-guided customised ablation treatment are gaining high importance and undergoing rapid evolution. Nowadays, PTK is an effective treatment modality for superficial corneal pathologies. Primary indications are decreased epithelial adherence, superficial opacifications and an irregular corneal surface. For the right indication and successful treatment of corneal pathologies with PTK, a knowledge of the size, depth and nature of the pathology, as well as the refractive status of both eyes is important. Next to slit-lamp examination, objective measuring systems like the topography, confocal microscopy and the anterior segment OCT facilitate presurgical planning. Regarding the treatment procedure the surgeon can choose between a variety of methods. PTK can be combined with manual epithelial debridement or done by only using the excimer laser. In the case of an irregular corneal surface, depending on the pathology, masking fluids or topography-guided custom ablation protocols can increase the visual outcome. To avoid recurrence of the underlying pathology (e.g., corneal dystrophy, haze), the topical application of 0.02% mitomycin C for 20-60 seconds has proved to be a safe and effective procedure. If the surgeon considers all the patient-related factors carefully and manages to combine the available treatment options correctly, PTK embodies an effective and minimally invasive alternative to lamellar or penetrating keratoplasty.

Immediate and midterm follow-up results of excimer laser application in complex percutaneous coronary interventions: Report from a single center experience.

To assess the efficacy and safety of laser-assisted percutaneous coronary interventions (PCI) in an unselected population. One hundred consecutive patients, who underwent a laser assisted PCI between January 2008 and March 2012, were included in the present study. Fifty-one patients underwent laser ablation for thrombus vaporization (Group 1), 36 patients for neointima/plaque debulking (Group 2) and 13 patients for lesion compliance modification in calcified lesions (Group 3). The rate of in-hospital serious events was 2%. The cumulative laser success was 82%, and it was significantly higher for Group 1 and Group 2 in comparison with Group 3 (p = 0.001). Furthermore, the need for repeat revascularization was significantly higher in the Group 3 compared with the others two groups (46% vs. 8% for Group 1 and 11% for Group 2, p = 0.03). The MACE rate was 14%. There was a trend toward a higher MACE rate in the Group 3 compared with others two groups (p = 0.05). Laser ablation is an effective and safe tool for complex PCI. Patients underwent laser for thrombus vaporization or for neointima/plaque debulking had better immediate success and better outcome at follow-up than patients underwent laser for lesion compliance modification.

Controlled biopolymer roughness induced by plasma and excimer laser treatment

A new method for biopolymer poly-L-lactic-acid (PLLA) surface nanostructuring with surface plasmon reso- nance appearance is proposed. The motivation of this work is to determine optimal conditions for rough or flat biopolymer surface which may find broad application in tissue engineering as biocompatible carrier for various types of cell lines. A combination of plasma pre-treatment with consequent excimer laser exposure is proposed as a method for increasing the roughness of PLLA surface and changing its morphology. The focus of this paper is to determine morphology changes in combination with mass loss changes. The ablation loss and morphology of PLLA was induced by excimer laser exposure of plasma pre-treated PLLA with different laser fluencies and number of pulses. The combination of a certain input parameters of plasma pre-treatment together with laser exposure induces extensive physico-chemical changes (morphology, contact angle, optical properties) on polymer surface with dramatic roughness increase. Gravimetric studies have revealed an extensive polymer ablation after excimer laser application. The effect of surface plasmon resonance was observed in laser modified PLLA. Conditions for PLLA surface flattening are also proposed.

Treatment of plaque‐type psoriasis with the 308 nm excimer laser in combination with dithranol or calcipotriol

Purpose: The combination of excimer laser and topical treatment has not been studied in clinical trials. This within‐patient comparison study evaluates the response rates of plaque‐type psoriasis after treatment with topical only (dithranol or calcipotriol), laser only, and combination therapy with topical medication and laser.Materials and methods: A total of 61 patients with psoriatic plaques located at symmetric body areas (PASI ≥ 6) were screened, 59 were enrolled, 54 completed treatment and 45 completed the 6 months follow‐up. Treatments with the excimer laser were performed twice weekly until resolution or a maximum of 15 treatments. Each ointment was applied on one of the test lesions, which had to be at least 10 cm apart from each other. Efficacy was rated with a modified PASI score.Results: At the end of the treatment phase only one patient in both topical therapy regimens met the criteria of partial clearance (modified PASI ≤ 2). The combined therapies resulted in 23 cases of partial clearance in both treatment arms. Four areas treated with calcipotriol, respectively six areas treated with dithranol resulted in total clearance at the end of the treatment phase. The average reduction of modified PASI scores was higher in combination than in topical treatment alone (49.8% calcipotriol + excimer versus 22.9% calcipotriol, 49.7% dithranol + excimer versus 26.8% dithranol). After six months there was a total clearance of 30.5% dithranol + excimer.Conclusions: Treatment of plaque‐type psoriasis with laser in combination with topical treatment is a safe and effective therapy. The best long‐term results can be obtained by the application of dithranol and excimer laser.

UV optical properties of thin film oxide layers deposited by different processes

UV optical properties of thin film layers of compound and mixed oxide materials deposited by different processes are presented. Japan Electron Optics Laboratory plasma ion assisted deposition (JEOL PIAD), electron beam with and without IAD, and pulsed DC magnetron sputtering were used. Comparisons are made with published deposition process data. Refractive indices and absorption values to as short as 145 nm were measured by spectroscopic ellipsometry (SE). Electronic interband defect states are detected that are deposition-process dependent. SE might be effective in identifying UV optical film quality, especially in defining processes and material composition beneficial for high-energy excimer laser applications and environments requiring stable optical properties.