The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Isak I. Beilis - One of the best experts on this subject based on the ideXlab platform.
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Vacuum arc cathode spot motion in oblique magnetic fields: An interpretation of the Robson experiment
Physics of Plasmas, 2016Co-Authors: Isak I. BeilisAbstract:A model was developed of vacuum arc cathode spot motion in a magnetic field that obliquely intercepts the cathode surface. The model takes into account a force under an electric field caused by retrograde spot motion across the normal component of the magnetic field, producing a drift velocity component in the direction of the Acute Angle between the magnetic field and the cathode surface. The relationship between velocity of the retrograde direction and drift velocity of the cathode spot motion to the Acute Angle was developed. The dependencies of the drift Angle θ on the Acute Angle φ, magnetic field strength B, and arc current I were calculated. It was found that the calculated θ increased with φ, B, and I in accordance with Robson's measurements.
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A model of vacuum arc cathode spot motion in an oblique magnetic field
2016 27th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV), 2016Co-Authors: Isak I. BeilisAbstract:A model of vacuum arc cathode spot motion in a magnetic field which obliquely intercepts the cathode surface was developed. The model takes in account an electrical force generated by spot motion across the normal component of the magnetic field, which accelerates plasma in the direction of the opening of the Acute Angle. A relation between the drift Angle (between the retrograde direction and the cathode spot motion) and the Acute Angle formed by the intersection of the magnetic field lines with the cathode surface, was developed. The dependencies of the drift Angle on the Acute Angle and magnetic field strength measured in Robson's experiment were analyzed.
Sarwat Salim - One of the best experts on this subject based on the ideXlab platform.
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bilateral Acute Angle closure glaucoma as a complication of facedown spine surgery
The Spine Journal, 2010Co-Authors: Michael S Singer, Sarwat SalimAbstract:Abstract Background context Multiple studies have reported that facedown positioning can result in elevation of intraocular pressure (IOP) in individuals susceptible to Angle-closure glaucoma. Before advances in diagnostic modalities, prone tests were popularly performed in ophthalmology practices as provocative tests for detecting potentially occludable Angles. In patients with a positive test result, direct observation shows that the anterior chamber shallows and the Angle closes over time, compromising aqueous humor outflow facility. Furthermore, the degree of Angle narrowing is proportional to the rise in IOP. A common scenario involving a prone position is spine surgery, which can last several hours with the patient unconscious. Purpose To report a case of a patient who developed bilateral Acute Angle-closure glaucoma after facedown spine surgery. Study design Case report and literature review. Methods A 68-year-old Caucasian woman presented with persistent low back and left lower extremity pain. History was remarkable for L5 radicular pain, spinal stenosis, and an L3–L4 laminectomy performed 6 months previously. Plain films showed instability at the L4–L5 level and degenerative disc disease and scoliosis at L2–L4. The patient underwent spinal fusion surgery. Results Postoperatively, the patient complained of pain in the left eye accompanied with nausea and vomiting. Ophthalmology consultation confirmed the diagnosis of bilateral Acute Angle-closure glaucoma, requiring medical therapy initially followed by laser iridotomies in both eyes. Conclusions Bilateral Acute Angle-closure glaucoma may occur as a complication of facedown spine surgery. It is essential for anesthesiologists and surgeons to be aware of this complication for accurate diagnosis and timely intervention. A preoperative evaluation by an ophthalmologist should be considered for those individuals who are at increased risk of developing Angle-closure glaucoma, such as certain ethnicities, including Asians, Canadians, and Eskimos; female gender; hyperopic eyes with a shorter axial length; family history; history of previous attacks in the subject; and so forth. Prophylactic laser iridotomy in eyes with potentially occludable Angles is a simple and safe office procedure that can prevent potentially devastating visual outcomes.
Peizeng Yang - One of the best experts on this subject based on the ideXlab platform.
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vogt koyanagi harada disease presenting as Acute Angle closure glaucoma at onset
Clinical and Experimental Ophthalmology, 2011Co-Authors: Peizeng Yang, Xiaoli Liu, Hongyan Zhou, Wenjuan Guo, Chunjiang Zhou, Aize KijlstraAbstract:Background: To investigate the clinical features of Vogt-Koyanagi-Harada (VKH) disease presenting as Acute Angle closure glaucoma at onset. Design: Retrospective non-comparative case series. Participants: Four hundred and eighty-six VKH patients seen from February 2001 to March 2010. Methods: The history and clinical findings of all patients were reviewed. Auxiliary examinations, including ultrasound biomicroscopy, fundus fluorescein angiography and optical coherence tomography, were performed in certain cases. Corticosteroids with or without cyclosporine A were used to treat these patients. Main Outcome Measure: Patients' demographics, clinical presentation and auxiliary examination findings. Results: Eight out of 486 VKH patients were misdiagnosed as Acute Angle closure glaucoma. The mean age of these eight patients was 55.6 years. Six patients were female. The mean intraocular pressure (IOP) at disease onset was 32.9 mmHg. All of these patients had a shallow anterior chamber and a narrow or closed Angle at their first visit. The complaints of these patients were mostly headache and sudden decreased vision in both eyes. Alterations shown on ultrasound biomicroscopy included detachment of the ciliary body and peripheral choroid. The increased IOP did not respond to anti-glaucoma therapy, but resolved following treatment with corticosteroids. The eye of one patient was enucleated after failed trabeculectomies prior to referral to our uveitis centre. Conclusion: VKH disease presenting with a bilateral increased IOP mostly occurs in older women. The strikingly decreased visual acuity associated with mild to moderate increased IOP is a clue to the diagnosis. The increased IOP responded well to corticosteroids but not to anti-glaucoma treatment.
Shaohong Qian - One of the best experts on this subject based on the ideXlab platform.
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bilateral Acute Angle closure glaucoma as a presentation of vogt koyanagi harada syndrome in four chinese patients a small case series
Ocular Immunology and Inflammation, 2013Co-Authors: Jing Yao, Yuhong Chen, Tingting Shao, Zhihong Ling, Wenji Wang, Shaohong QianAbstract:Purpose: To report the clinical features of Vogt-Koyanagi-Harada syndrome presented with bilateral Acute Angle closure glaucoma in 4 Chinese patients.Methods: The medical records were retrospectively reviewed.Results: Visual acuity ranged from counting fingers before the eye to 6/30. Intraocular pressure ranged from 22.2 to 29.7 mmHg with or without anterior chamber inflammation. Mild vitritis and massive exudative retinal detachment were seen. B scan and fundus fluorescein angiography supported the diagnosis. After corticosteroid treatment, the increased intraocular pressure was resolved with deepened anterior chamber and open Angle. Inflammation was controlled and visual acuity was improved.Conclusions: Bilateral Acute Angle closure glaucoma could be the initial symptom of Vogt-Koyanagi-Harada syndrome. Mild increased intraocular pressure in association with moderate to severe visual disturbance in both eyes is an important sign of this diagnosis. Careful fundus examination and B scan are helpful in dia...
Robert Ritch - One of the best experts on this subject based on the ideXlab platform.
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combined phacoemulsification and goniosynechialysis for uncontrolled chronic Angle closure glaucoma after Acute Angle closure glaucoma
Ophthalmology, 1999Co-Authors: Chaiwat Teekhasaenee, Robert RitchAbstract:Abstract Objective To evaluate combined phacoemulsification, posterior chamber intraocular lens (PCIOL) implantation, and goniosynechialysis (phaco-GSL) prospectively in eyes with more than 180° of peripheral anterior synechiae (PAS) and uncontrolled intraocular pressure (IOP) when performed within 6 months of an attack of Acute Angle-closure glaucoma (ACG). Design Prospective, noncontrolled clinical trial. Participants Patients who had presented with Acute ACG and had persistently uncontrolled IOP despite successful laser iridotomy for pupillary block and argon laser peripheral iridoplasty for continued appositional closure after iridotomy. Intervention After the completion of phacoemulsification and posterior chamber lens implantation, goniosynechialysis was performed in 52 eyes of 48 patients. Main outcome measures Postoperative visual acuity, IOP, extent of PAS, and number of medications, if any, required for IOP control. Results Intraocular pressure was less than 20 mmHg in 47 eyes (90.4%) without medications; 4 were controlled with medications and 1 required filtration. Mean extent of PAS was reduced from 310° to 60°. Peripheral anterior synechiae formation or IOP elevation did not recur after 3 months after surgery up to 6 years. Eight patients achieved 20/20 visual acuity, while 44 patients had less than 20/20 visual acuity. No patient had worse visual acuity after surgery compared to before surgery. Conclusion Phaco-GSL and PCIOL implantation is effective in reducing PAS and IOP and improving visual acuity in eyes with persistent chronic ACG when performed within 6 months after treatment for Acute ACG.
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should patients with anatomically narrow Angles have prophylactic iridectomy ii definitive signs and gonioscopic visualization of appositional Angle closure are indications for prophylactic laser iridectomy
Survey of Ophthalmology, 1996Co-Authors: Robert RitchAbstract:Abstract In this set of articles, the authors outline methods and criteria for determining which patients with anatomically narrow Angles should have laser iridectomy to prevent Acute Angle-closure glaucoma.