2,227 research outputs found

    Dynamical coupled-channel model of meson production reactions in the nucleon resonance region

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    A dynamical coupled-channel model is presented for investigating the nucleon resonances in the meson production reactions induced by pions and photons. The model is based on an energy-independent Hamiltonian which is derived from a set of Lagrangians by using a unitary transformation method. By applying the projection operator techniques,we derive a set of coupled-channel equations which satisfy the unitarity conditions within the channel space spanned by the considered two-particle meson-baryon states and the three-particle ππN\pi\pi N state. We present and explain in detail a numerical method based on a spline-function expansion for solving the resulting coupled-channel equations which contain logarithmically divergent one-particle-exchange driving terms resulted from the ππN\pi\pi N unitarity cut. We show that this driving term can generate rapidly varying structure in the reaction amplitudes associated with the unstable particle channels. It also has large effects in determining the two-pion production cross sections. Our results indicate that cautions must be taken to interpret the N∗N^* parameters extracted from using models which do not include ππN\pi\pi N cut effects.Comment: 73 pages, 20 figure

    Eyelid Cosmetic Enhancements and Their Associated Ocular Adverse Effects

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    Numerous cosmetic enhancements and augmentations to the natural appearance of the periorbital area are readily available today. Due to the increasing popularity of these cosmetic procedures, it is important for ophthalmologists to be aware of their potential risks, complications and adverse effects. The aim of this literature review was to introduce some of the most common ocular cosmetic enhancements and provide a comprehensive overview of their associated adverse effects reported in various medical journals. PubMed, Embase, and Google Scholar were used to identify articles related to the following ocular cosmetic procedures; eyelash extensions, permanent eyelid tattooing, and eyelash dyeing. The most common complication associated with eyelash extensions was allergic blepharitis (79%). Allergic granulomatous reactions were the predominant complication in patients who underwent eyelid tattooing (56%). Besides, 60% of subjects who underwent eyelash dyeing experienced allergic contact dermatitis as the most common adverse effect. Although millions of these procedures are performed annually without any adverse effects, reports of complications continue to increase in the literature. Knowledge of the possible adverse effects associated with these enhancements is important for eye care providers and licensed estheticians to be aware of given both the direct and indirect effects they may have on ocular health and visual outcomes

    Keratoconus in a patient with Alport syndrome: A case report

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    BACKGROUND Known ocular manifestations of Alport syndrome include features such as anterior lenticonus and fleck retinopathy. Reports of keratoconus in such patients are limited. We report tomographic findings consistent with keratoconus in a patient with Alport syndrome. CASE SUMMARY A 52-year-old female was referred to our ophthalmology clinic with decreased vision and increased tearing. She was diagnosed with stage III Alport syndrome two years prior. Upon examination she was found to have average keratometries of 48 D bilaterally with tomographic evidence of keratoconus. CONCLUSION Although a rare presentation, concurrent Alport syndrome and keratoconus should be considered when reviewing the ocular health of Alport syndrome patients and appropriate management steps should be taken upon the diagnosis

    Eyelid Cosmetic Enhancements and Their Associated Ocular Adverse Effects

    Get PDF
    Numerous cosmetic enhancements and augmentations to the natural appearance of the periorbital area are readily available today. Due to the increasing popularity of these cosmetic procedures, it is important for ophthalmologists to be aware of their potential risks, complications and adverse effects. The aim of this literature review was to introduce some of the most common ocular cosmetic enhancements and provide a comprehensive overview of their associated adverse effects reported in various medical journals. PubMed, Embase, and Google Scholar were used to identify articles related to the following ocular cosmetic procedures; eyelash extensions, permanent eyelid tattooing, and eyelash dyeing. The most common complication associated with eyelash extensions was allergic blepharitis (79%). Allergic granulomatous reactions were the predominant complication in patients who underwent eyelid tattooing (56%). Besides, 60% of subjects who underwent eyelash dyeing experienced allergic contact dermatitis as the most common adverse effect. Although millions of these procedures are performed annually without any adverse effects, reports of complications continue to increase in the literature. Knowledge of the possible adverse effects associated with these enhancements is important for eye care providers and licensed estheticians to be aware of given both the direct and indirect effects they may have on ocular health and visual outcomes

    Use of Rho kinase Inhibitors in Ophthalmology: A Review of the Literature

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    The use of Rho Kinase (ROCK) inhibitors as therapeutic agents in ophthalmology has been a topic of discussion for several years, particularly in the realm of glaucoma, Fuchs’ endothelial dystrophy, and diabetic retinopathy. In this review, the authors provide a detailed and comprehensive overview of the published literature on the use of Rho kinase inhibitors for the aforementioned purposes. A thorough search of several databases was conducted to find sufficient literature on ROCK inhibitors. This research found strong evidence demonstrating that inhibition of Rho kinase significantly decreases IOP, increases healing of the corneal endothelium, and decreases progression of diabetic retinopathy. The main side effect of ROCK inhibitors is conjunctival hyperemia that is often present in more than half of the patients in certain formulations. Additional clinical trials investigating the reviewed treatment options of Rho kinase inhibitors are necessary to further validate previous findings on the topic. Nonetheless, it is clear that Rho kinase inhibitors have the potential to be another potent therapeutic option for several chronic diseases in ophthalmology

    Use of Rho kinase Inhibitors in Ophthalmology: A Review of the Literature

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    The use of Rho Kinase (ROCK) inhibitors as therapeutic agents in ophthalmology has been a topic of discussion for several years, particularly in the realm of glaucoma, Fuchsñ€ℱ endothelial dystrophy, and diabetic retinopathy. In this review, the authors provide a detailed and comprehensive overview of the published literature on the use of Rho kinase inhibitors for the aforementioned purposes. A thorough search of several databases was conducted to find sufficient literature on ROCK inhibitors. This research found strong evidence demonstrating that inhibition of Rho kinase significantly decreases IOP, increases healing of the corneal endothelium, and decreases progression of diabetic retinopathy. The main side effect of ROCK inhibitors is conjunctival hyperemia that is often present in more than half of the patients in certain formulations. Additional clinical trials investigating the reviewed treatment options of Rho kinase inhibitors are necessary to further validate previous findings on the topic. Nonetheless, it is clear that Rho kinase inhibitors have the potential to be another potent therapeutic option for several chronic diseases in ophthalmology

    Corneal Refractive Surgery in Patients with History of Optic Neuritis

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    Purpose The purpose of this study was to evaluate the risk of recurrence of optic neuritis after corneal refractive surgery in patients with a history of optic neuritis and to examine the safety and efficacy of the procedure in this population. Methods This was a retrospective chart review of patients with a history of optic neuritis who underwent laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) at a single tertiary center from June 1996 to December 2014. Fifteen eyes of 14 patients were included in this study. Visual acuity before and after the surgery was recorded. Patients were followed-up for over five years postoperatively for the recurrence of optic neuritis. Results The average LogMAR best corrected visual acuity (BCVA) preoperatively was 0.12 ± 0.19 (–0.10 to 0.60) and postoperatively was 0.06 ± 0.10 (–0.10 to 0.30). No eyes lost lines of BCVA. The average LogMAR uncorrected distance visual acuity (UDVA) after surgery was 0.12 ± 0.13 (0.00 to 0.48). Twenty-eight percent of patients reached a UDVA of 20/20 or better after refractive surgery. Optic neuritis recurred in 3/15 (20%) eyes and 3/14 patients (21%). Conclusion While corneal refractive procedures appear safe in patients with a history of optic neuritis, our data suggest that their efficacy may be reduced

    Corneal Refractive Surgery in Patients with History of Optic Neuritis

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    Purpose: The purpose of this study was to evaluate the risk of recurrence of optic neuritis after corneal refractive surgery in patients with a history of optic neuritis and to examine the safety and efficacy of the procedure in this population. Methods: This was a retrospective chart review of patients with a history of optic neuritis who underwent laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) at a single tertiary center from June 1996 to December 2014. Fifteen eyes of 14 patients were included in this study. Visual acuity before and after the surgery was recorded. Patients were followed-up for over five years postoperatively for the recurrence of optic neuritis. Results: The average LogMAR best corrected visual acuity (BCVA) preoperatively was 0.12 ± 0.19 (–0.10 to 0.60) and postoperatively was 0.06 ± 0.10 (–0.10 to 0.30). No eyes lost lines of BCVA. The average LogMAR uncorrected distance visual acuity (UDVA) after surgery was 0.12 ± 0.13 (0.00 to 0.48). Twenty-eight percent of patients reached a UDVA of 20/20 or better after refractive surgery. Optic neuritis recurred in 3/15 (20%) eyes and 3/14 patients (21%). Conclusion: While corneal refractive procedures appear safe in patients with a history of optic neuritis, our data suggest that their efficacy may be reduced

    Use of Rho kinase Inhibitors in Ophthalmology: A Review of the Literature

    Get PDF
    The use of Rho Kinase (ROCK) inhibitors as therapeutic agents in ophthalmology has been a topic of discussion for several years, particularly in the realm of glaucoma, Fuchs’ endothelial dystrophy, and diabetic retinopathy. In this review, the authors provide a detailed and comprehensive overview of the published literature on the use of Rho kinase inhibitors for the aforementioned purposes. A thorough search of several databases was conducted to find sufficient literature on ROCK inhibitors. This research found strong evidence demonstrating that inhibition of Rho kinase significantly decreases IOP, increases healing of the corneal endothelium, and decreases progression of diabetic retinopathy. The main side effect of ROCK inhibitors is conjunctival hyperemia that is often present in more than half of the patients in certain formulations. Additional clinical trials investigating the reviewed treatment options of Rho kinase inhibitors are necessary to further validate previous findings on the topic. Nonetheless, it is clear that Rho kinase inhibitors have the potential to be another potent therapeutic option for several chronic diseases in ophthalmology

    Astigmatic correction with implantation of a light adjustable vs monofocal lens: a single site analysis of a randomized controlled trial

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    AIM To evaluate the light adjustable lens (LAL) vs a standard monofocal lens in achieving target astigmatic refraction and improving postoperative uncorrected distance visual acuity (UDVA). METHODS This randomized controlled clinical trial included 40 patients with pre-existing astigmatism and visually significant cataract. Twenty-eight patients received the LAL and 12 control patients received a monofocal intraocular lens (IOL) after cataract extraction at a single institution. The patients with the LAL underwent adjustment by ultraviolet (UV) light postoperatively plus subsequent lock-in procedures and all patients returned to clinic for follow up of study parameters at 6, 9, and 12mo. Manifest refraction, distance visual acuity, and adverse events were recorded at each visit. RESULTS The mean cylinder before adjustment in eyes with the LAL was -0.89±0.58 D (-2.00 to 0.00 D) and -0.34±0.34 D (-1.25 to 0.00 D) after lock-in (P=1.68x10−8). The mean cylinder in patients with the monofocal lens was -1.00±0.32 D (-1.50 to -0.50 D) at 17-21d postoperatively, which was statistically different from the LAL cylinder post lock-in (P=1.43x10−6). UDVA in the LAL group was 20/20 or better in 79% of patients post lock-in with good stability over 12mo compared with 33% of the control patients with UDVA of 20/20 or better. CONCLUSION These results demonstrate that the LAL is more effective in achieving target refractions and improving postoperative UDVA in patients with pre-existing corneal astigmatism than a standard monofocal lens
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