Pulsed UV laser technologies for ophthalmic surgery

Ражев, А. М.; Черных, В. В.; Bagayev, S. N.; Churkin, Dmitry V.; Kargapoltsev, Evgeny S.; Iskakov, I. A.; Ермакова, О. В.

doi:10.1088/1742-6596/793/1/012022

Cited by 6 publications

(6 citation statements)

References 10 publications

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“…Research and development in the area of AlGaN-based deep ultraviolet (DUV/UVC), ultraviolet-B (UVB) and ultraviolet-A (UVA) light-emitting diodes (LEDs) as well as laser diode (LD) technologies to help address the concerns about public health and environmental issues in accordance with the Minamata Convention of 2020 are quite critical to replace toxic and bulky mercury (Hg) UV-vapor lamps [1][2][3][4][5][6][7][8][9][10][11]. To combat the growth and expansion of SARS-CoV-2, which is the virus that causes fatal COVID-19 infections in the human body, DUV light can be used to kill this novel virus [1].…”

Section: Introductionmentioning

confidence: 99%

“…Similarly, UVB LEDs and LD light sources with Narrow-band (NB) emission are importantly needed for immunotherapy (psoriasis, vitiligo: 310 nm), vulgaris treatment (310 nm), the production of vitamin D 3 in the human body (293-304 nm), as well as for suppressing the tomato mosaic virus (ToMV) in tomatoes (293 nm) and the production of phytochemicals in the green leaves of vegetables (310 nm) [4,5,7,[9][10][11]. When it comes to UV laser application in the area of medical science, then surgery of the eye's cornea in the form of 'laser-assisted in situ keratomileusis (LASIK)' is possible [3]. Keratomileusis is the surgical reshaping of the cornea in the human eye, which is carried out to correct the refractive error [3].…”

Section: Introductionmentioning

confidence: 99%

“…When it comes to UV laser application in the area of medical science, then surgery of the eye's cornea in the form of 'laser-assisted in situ keratomileusis (LASIK)' is possible [3]. Keratomileusis is the surgical reshaping of the cornea in the human eye, which is carried out to correct the refractive error [3]. UV-laser light sources can be used for fine machining of metals or other advanced materials too [12].…”

Section: Introductionmentioning

confidence: 99%

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Impact of Mg level on lattice relaxation in a p-AlGaN hole source layer and attempting excimer laser annealing on p-AlGaN HSL of UVB emitters

et al. 2020

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Mg-doped p-type semiconducting aluminium-gallium-nitride hole source layer (p-AlGaN HSL) materials are quite promising as a source of hole ‘p’ carriers for the ultraviolet-B (UVB) light-emitting diodes (LEDs) and laser diodes (LDs). However, the p-AlGaN HSL has a central issue of low hole injection due to poor activation of Mg atoms, and the presence of unwanted impurity contamination and the existence of a localized coherent state. Therefore, first the impact of the Mg level on the crystallinity, Al composition and relaxation conditions in the p-AlGaN HSL were studied. An increasing trend in the lattice-relaxation ratios with increasing Mg concentrations in the p-AlGaN HSL were observed. Ultimately, a 40%–60% relaxed and 1.4 μm thick p-AlGaN HSL structure with total threading dislocation densities (total-TDDs) of approximately ∼8–9 × 108 cm−2 was achieved, which almost matches our previous design of a 4 μm thick and 50% relaxed n-AlGaN electron source layer (ESL) with total-TDDs of approximately ∼7–8 × 108 cm−2. Subsequently, structurally a symmetric p–n junction for UVB emitters was accomplished. Finally, the influence of excimer laser annealing (ELA) on the activation of Mg concentration and on suppression of unwanted impurities as well as on the annihilation of the localized energy state in the p-AlGaN HSL were thoroughly investigated. ELA treatment suggested a reduced Ga–N bonding ratio and increased Ga–O, as well as Ga–Ga bonding ratios in the p-AlGaN HSL. After ELA treatment the localized coherent state was suppressed and, ultimately, the photoluminescence emission efficiency as well as conductivity were drastically improved in the p-AlGaN HSL. By using lightly polarized p-AlGaN HSL assisted by ELA treatment, quite low resistivity in p-type AlGaN HSL at room temperature (hole concentration is ∼2.6 × 1016 cm−3, the hole mobility is ∼9.6 cm2 V1 s−1 and the resistivity is ∼24.39 Ω. cm) were reported. ELA treatment has great potential for localized activation of p-AlGaN HSL as well as n- and p-electrodes on n-AlGaN and p-AlGaN contact layers during the flip-chip (FC) process in low operating UVB emitters, including UVB lasers.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impact of Mg level on lattice relaxation in a p-AlGaN hole source layer and attempting excimer laser annealing on p-AlGaN HSL of UVB emitters

et al. 2020

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“…High-intensity lasers (>10 W) have been gaining traction for medical application, orthodontics pain management, [30] rapid dentin bonding, [31] and tissue ablation in ophthalmic surgeries. [32] Recent development and commercialization of UVA laser diodes are underway (currently prohibitively expensive), but the miniaturization to 5.6 mm diode "TO can" allows a 72 µm spot size at the same intensities described above (70 mW → 17 µW µm −2 ) revealing the advantages and portability of diode-prototype developments. [33] High intensity LEDs with millimeter spot widths are attractive but their electronic modulation to generate pulses (0.5-5 MHz) are limited by their sub-microseconds on/off slew rates.…”

Section: Light-activated Tissue Adhesives Are Limited To Low Light Domentioning

confidence: 99%

Pulsed Laser Activation of Carbene Bioadhesive Boosts Bonding Strength

Shah

Kartheek

Gandhi

et al. 2019

Macro Materials & Eng

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Light‐activated tissue adhesives are limited to low light doses (50 J) and intensities (<1 W cm−2) due to photo‐to‐thermal heat generation. Low intensities have the disadvantage of limited penetration depths with retarded crosslinking kinetics, which impairs carbene‐based crosslinking strategies that compete with nitrogen evolution and gas nucleation. These limitations are circumvented by a trade‐off between high‐intensity activation while reducing the exposure surface area. Continuous or pulsed activation by line scanning the carbene precursor adhesive allows curing a higher surface area/volume ratio while preventing localized heat generation. By optimizing irradiation with a pulsed laser scan, the adhesion strength is improved by 17‐fold over ultraviolet A (UVA) light emitting diodes (LEDs) and is on par with bioadhesive gold standard of topical cyanoacrylates. Overall, this improved method of photo‐activation applies to other industrial and clinical photocuring adhesives where limits on UVA dose constrain exposure intensities.

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“…Far-ultraviolet excimer lasers (150–200 nm) allow evaporating corneal epithelium and stroma and making cuts of precise depth and shape without thermal damage to the adjacent tissue [4]. Thereby, they are utilized in vision correction surgeries, such as laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) [5]. In both operations excimer laser is employed to remodel the corneal stroma.…”

Section: Introductionmentioning

confidence: 99%

Mitochondria-targeted antioxidant SKQ1 protects cornea from oxidative damage induced by ultraviolet irradiation and mechanical injury

et al. 2018

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BackgroundCornea protects the eye against natural and anthropogenic ultraviolet (UV) damage and mechanical injury. Corneal incisions produced by UV lasers in ophthalmic surgeries are often complicated by oxidative stress and inflammation, which delay wound healing and result in vision deterioration. This study trialed a novel approach to prevention and treatment of iatrogenic corneal injuries using SkQ1, a mitochondria-targeted antioxidant approved for therapy of polyethiological dry eye disease.MethodsRabbit models of UV-induced and mechanical corneal damage were employed. The animals were premedicated or treated with conjunctival instillations of 7.5 μM SkQ1. Corneal damage was assessed by fluorescein staining and histological analysis. Oxidative stress in cornea was monitored by measuring malondialdehyde (MDA) using thiobarbituric acid assay. Total antioxidant activity (AOA) was determined using hemoglobin/H2O2/luminol assay. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were measured using colorimetric assays.ResultsIn both models corneas exhibited fluorescein-stained lesions, histologically manifesting as basal membrane denudation, apoptosis of keratocytes, and stromal edema, which were accompanied by oxidative stress as indicated by increase in lipid peroxidation and decline in AOA. The UV-induced lesions were more severe and long healing as corneal endothelium was involved and GPx and SOD were downregulated. The treatment inhibited loss of keratocytes and other cells, facilitated re-epithelialization and stromal remodeling, and reduced inflammatory infiltrations and edema thereby accelerating corneal healing approximately 2-fold. Meanwhile the premedication almost completely prevented development of UV-induced lesions. Both therapies reduced oxidative stress, but only premedication inhibited downregulation of the innate antioxidant activity of the cornea.ConclusionsSkQ1 efficiently prevents UV-induced corneal damage and enhances corneal wound healing after UV and mechanical impacts common to ocular surgery. Its therapeutic action can be attributed to suppression of mitochondrial oxidative stress, which in the first case embraces all corneal cells including epitheliocytes, while in the second case affects residual endothelial cells and stromal keratocytes actively working in wound healing. We suggest SkQ1 premedication to be used in ocular surgery for preventing iatrogenic complications in the cornea.

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Pulsed UV laser technologies for ophthalmic surgery

Cited by 6 publications

References 10 publications

Impact of Mg level on lattice relaxation in a p-AlGaN hole source layer and attempting excimer laser annealing on p-AlGaN HSL of UVB emitters

Impact of Mg level on lattice relaxation in a p-AlGaN hole source layer and attempting excimer laser annealing on p-AlGaN HSL of UVB emitters

Pulsed Laser Activation of Carbene Bioadhesive Boosts Bonding Strength

Mitochondria-targeted antioxidant SKQ1 protects cornea from oxidative damage induced by ultraviolet irradiation and mechanical injury

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