251 research outputs found
European Glaucoma Society - Terminology and guidelines for glaucoma, 6th Edition
No full text: We practice medicine in times of exponentially increasing medical knowledge. In 1950, it was estimated that the doubling time was 50 years; by 1980, it was 7 years and by 2010, 3.5 years. In 2020, it was projected to be just 73 days! To continue to practice evidence-based medicine and to provide the best possible care for our patients, clinicians need to adapt their strategies to keep their knowledge up to date. There will always be a role for critical appraisal of individual studies in the field of a clinician's practice, but with such an increase in the volume of published research, it becomes impossible to appraise all relevant material. For this reason, sources of distilled knowledge, such as the EGS Guidelines, become essential references for best practice medicine. Rigorous methods for evidence synthesis, such as the systematic reviews overseen by Cochrane, provide a comprehensive summary of the current state of knowledge for important clinical questions. However, for many clinical uncertainties, there is little or no high-quality evidence, let alone an evidence synthesis. Where evidence is lacking, practice guidance needs to be built from expert opinion and consensus, while acknowledging the limitations of such an approach. Expert opinion, derived from sound medical knowledge and years of practice experience, also has an important role in understanding the relevance of lines of evidence and the nuances of implementing them in practice. Thus, the expert commentary around the evidence base given in these Guidelines is essential for proper implementation of published evidence. Importantly, the EGS Guidelines also include 'Choosing wisely' elements indicating actions which should be avoided due to insufficient evidence and/or unsubstantiated belief. Guidelines need regular updating to take account of new knowledge and aspects of clinical care that have not been given sufficient emphasis in the past. This 6th Edition of the EGS Guidelines includes an updated 'evidence based' section with new clinical questions and evidence-based answers. The section 'What matters to patients' has also been updated, recognising that, because Guidelines are typically written by clinicians for clinicians, there have been gaps in understanding the patient perspective. The updated section now has direct input from the Expert by Experience patient advisors in the EGS Patient Involvement Project and includes eight Tips for Doctors in their communication with patients. The Guidelines team, led by Drs Pazos, Traverso and Viswanathan, is to be congratulated for the 6th Edition of the Guidelines, updating and enhancing the previous edition, while maintaining the highly success format which gives a framework for glaucoma care, based on evidence synthesis and consensus expert opinion, and presented as a 'How to' manual for patient diagnosis and management. David (Ted) Garway-Heath Glaucoma UK Professor of Ophthalmology, UC
Publishing in Wireless and Wireline Environments
No full text994. 1994 Imielinski, T., and Viswanathan, S., "Adaptive Wireless Information Systems, " In the proceedings of SIGDBS (Special Interest Group in DataBase Systems) Conference, Tokyo - Japan, pp. 19-41, October 94. 1994 Viswanathan, S., and Imielinski, T., "Pyramid Broadcasting for Video On Demand Service," To appear in the Proceedings of IEEE Multimedia Computing and Networking Conference, San Jose - California, February 1995. 1994 Ph.D., in Computer Science - Rutgers, The State University of New Jersey. 167 [30] Evan I. Schwartz and Don Clark in "The New York Times" and "The Wall Street Journal - November 10 1993" respectively. [31] Samuel Sheng, Ananth Chandrasekaran, and R. W. Broderson, "A portable multimedia terminal for personal communications," IEEE Communications Magazine, pp. 64-75, December 1992. [32] W.D. Sincoskie, " System Architecture for a Large Scale Video On Demand Servic
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Device modeling and circuit design for ZTO based amorphous metal oxide TFTs
No full texttextAmorphous Oxide semiconductors have gained large interest in the display industry owing to their high carrier mobilities and low fabrication costs. In this thesis, n-channel solution based zinc-tin oxide (ZTO) thin-film transistors (TFTs) are studied from a circuit design perspective. The study includes an iterative process of circuit design, layout and test procedure of the fabricated devices in the lab. The device models used in circuit simulations are refined following the data fed back from each of these iterations which has enabled more accurate design of complex circuits using ZTO devices. The requirement and development of a physical compact model for performing accurate and predictive circuit simulations has been presented. The use of ZTO devices in low cost, transparent and flexible electronic applications has been investigated through the study of basic circuit blocks such as amplifiers, ring oscillators, inverters and a four stage Operational Amplifier.Electrical and Computer Engineerin
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Circuit design and device modeling of zinc-tin oxide TFTs
No full texttextAmorphous Oxide Semiconductors (AOS) are widely being explored in the field of flexible and transparent electronics. In this thesis, solution processed zinc-tin oxide (ZTO) n-channel TFT based circuits are studied. Inverters, single stage amplifiers and ring oscillators are designed, fabricated and tested. 7-stage ring oscillators with output frequencies up to 106kHz and 5-stage ring oscillators with frequencies up to 75kHz are reported.
A stable three stage op-amp with a buffered output is designed for a gain of 39.9dB with a unity gain frequency of 27.7kHz. A 7-stage ring oscillator with output frequency close to 1MHz is simulated and designed. The op-amp and the ring oscillator are ready to be fabricated and tested. An RPI model for a-Si, adapted to fit the ZTO device characteristics, is used for simulation.
Development of a new model based on the physics behind charge transport in ZTO devices is explored. An expression for gate bias dependent mobility in ZTO devices is derived.Electrical and Computer Engineerin
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Analog model parameter extraction-circuits for process monitoring
No full textA method for extracting the three parameters of the well-known level-2 Spice MOSFET-model namely threshold voltage, transconductance parameter, and channel length modulation is presented. Currently circuit design is based on CAD tools using complex model parameters obtained by laborious and expensive methods. While this is essential to design reliable systems on a chip, simpler analog techniques can be used for process monitoring. This work presents simple on-chip analog circuits that can characterize MOSFET just by measuring voltages and currents thus reducing the time and complexity of measurement. For this, on-chip implementation of two parameter extraction circuits are presented. The first circuit is for determining the threshold voltage Vth, and transconductance parameter (k). The second is to determine the channel-length modulation parameter (). These circuits generate voltages or currents proportional to model parameters Vth, k and . Simulation results and measured values from these circuits fabricated using TSMC 180nm process are presented. Results are also compared with accurate model parameters currently available in CAD tools to estimate the level of precision attainable using this method.Electrical and Computer Engineerin
Glycoprotein IIb/IIIa inhibitor associated severe thrombocytopenia in patients with coronary artery disease: Clinical course and outcomes
No full textThrombocytopenia, both at baseline and acquired throughout admission is associated with poor clinical outcomes in patients with coronary artery disease. It is not known whether severe thrombocytopenia in patients receiving glycoprotein IIb/IIIa inhibitors (GPI) carries the same risk as thrombocytopenia from other aetiologies. We identified 50 consecutive patients referred for percutaneous coronary intervention (PCI) who developed severe thrombocytopenia (<50 × 10(9) cells/l) and followed their clinical course to 30 days. Two groups were compared: (1) severe thrombocytopenia following GPI usage and (2) severe thrombocytopenia without exposure to GPI. Baseline platelet counts were higher in GPI group (201 ± 62 vs. 112 ± 83 × 10(9) cells/l, p < 0.05). Patients in GPI group had more profound thrombocytopenia yet quicker recovery of platelet counts. The GPI group received fewer blood product transfusions (red cells: 0.1 ± 0.4 vs. 1.3 ± 2.0, p < 0.05, platelets: 0.22 ± 0.6 vs. 1.1 ± 1.7, p < 0.05) and had lower event rates for the primary end point of 30-day mortality (3.7% vs. 42.1%, p < 0.05), and for major bleeding (0% vs. 15.8%, p < 0.05). In conclusion, GPI associated severe thrombocytopenia follows a distinct clinical course when compared to severe thrombocytopenia due to other aetiologies. Our results suggest that patients who develop severe thrombocytopenia following GPI therapy may be managed conservatively with careful monitoring.Girish Viswanathan, Ananth Kidambi, Adam Nelson, Gnanamoorthy Mayurathan, John Hardy, Patrick Kesteven, & Azfar Zama
Comparison of the effects of bimatoprost and a fixed combination of latanoprost and timolol on circadian intraocular pressure
No full textOBJECTIVE: To compare the effect of bimatoprost and the fixed combination of latanoprost and timolol (LTFC) on 24-hour mean intraocular pressure (IOP) after patients are switched from a nonfixed combination of latanoprost and timolol. DESIGN: Randomized, double-masked, multicenter clinical trial. PARTICIPANTS: Two hundred patients with glaucoma or ocular hypertension. METHODS: Included were patients who were controlled (IOP < 21 mmHg) on the nonfixed combination of latanoprost and timolol for at least 3 months before the baseline visit or patients on monotherapy with either latanoprost or timolol who were eligible for dual therapy not being fully controlled on monotherapy. The latter group of patients underwent a 6-week wash-in phase with the nonfixed combination of latanoprost and timolol before baseline IOP determination and study inclusion. Supine and sitting position IOPs were recorded at 8 pm, midnight, 5 am, 8 am, noon, and 4 pm at baseline, week 6, and week 12 visits. MAIN OUTCOME MEASURE: An analysis of covariance model was used for a noninferiority test of the primary efficacy variable, with mean area under the 24-hour IOP curve after 12 weeks of treatment as response variable and treatment, center, and baseline IOP as factors. A secondary analysis was performed on the within-treatment change from baseline. RESULTS: Mean baseline IOPs were 16.3+/-3.3 mmHg and 15.5+/-2.9.mmHg in the bimatoprost and LTFC groups, respectively. At week 12, mean IOPs were 16.1+/-2.5 mmHg for the bimatoprost group and 16.3+/-3.7 mmHg for the LTFC group, and no significant difference between the 2 treatment groups could be found. As compared with baseline, mean IOP increased by 0.3+/-3.6 mmHg during the day and decreased by 0.8+/-3.8 mmHg during the night in the bimatoprost group, whereas there were increases of 1.43+/-2.6 mmHg and 0.14+/-3.2 mmHg in the LTFC group, respectively. CONCLUSIONS: Bimatoprost is not inferior to the LTFC in maintaining IOP at a controlled level during a 24-hour period in patients switched from the nonfixed combination of latanoprost and timolol
International vision requirements for driver licensing and disability pensions: using a milestone approach in characterization of progressive eye disease
No full textAlain M Bron1, Ananth C Viswanathan2, Ulrich Thelen3, Renato de Natale4, Antonio Ferreras5, Jens Gundgaard6, Gail Schwartz7, Patricia Buchholz81Department of Ophthalmology, University Hospital, Dijon, France; 2Glaucoma Research Unit, Moorfields Eye Hospital NHS Foundation Trust and Department of Genetics, University College of London Institute of Ophthalmology, London, UK; 3Private Practice, Munster, Germany; 4Ospedale Civile di Monselice, Monselice, Italy; 5Ophthalmology, Miguel Servet University Hospital, Zaragoza, Spain; 6COWI, Kolding, Denmark; 7Wilmer Eye Institute, Johns Hopkins University, Glaucoma Consultants, Baltimore, MD, USA; 8Patricia Buchholz Consulting, Karlsruhe, GermanyObjective: Low vision that causes forfeiture of driver&rsquo;s licenses and collection of disability pension benefits can lead to negative psychosocial and economic consequences. The purpose of this study was to review the requirements for holding a driver&rsquo;s license and rules for obtaining a disability pension due to low vision. Results highlight the possibility of using a milestone approach to describe progressive eye disease.Methods: Government and research reports, websites, and journal articles were evaluated to review rules and requirements in Germany, Spain, Italy, France, the UK, and the US.Results: Visual acuity limits are present in all driver&rsquo;s license regulations. In most countries, the visual acuity limit is 0.5. Visual field limits are included in some driver&rsquo;s license regulations. In Europe, binocular visual field requirements typically follow the European Union standard of &ge;120&deg;. In the US, the visual field requirements are typically between 110&deg; and 140&deg;. Some countries distinguish between being partially sighted and blind in the definition of legal blindness, and in others there is only one limit.Conclusions: Loss of driving privileges could be used as a milestone to monitor progressive eye disease. Forfeiture could be standardized as a best-corrected visual acuity of &lt;0.5 or visual field of &lt;120&deg;, which is consistent in most countries. However, requirements to receive disability pensions were too variable to standardize as milestones in progressive eye disease. Implementation of the World Health Organization criteria for low vision and blindness would help to establish better comparability between countries.Keywords: driver&rsquo;s license requirements, glaucoma, health outcomes, progressive eye diseas
Visual function in glaucoma: Improving the assessment of computerised visual fields
No full textGlaucoma is a leading cause of world blindness. In order to ascertain whether the disease is progressive or stable, glaucoma patients' visual function is monitored at regular intervals by testing the visual field using the technique of automated perimetry. The numerical data obtained, relating to the spatial co-ordinates of the test locations and light sensitivities at those locations, are amenable to sophisticated statistical analysis. This thesis centres on a method for detecting glaucomatous change in serial visual fields known as pointwise linear regression: univariate linear regression of sensitivity on time is performed for each test location in the visual field. This method has been incorporated into a software package, PROGRESSOR. Results indicate that PROGRESSOR is superior to previously accepted glaucoma change probability software in the early detection of glaucomatous visual deterioration. A higher level of concordance between expert observers in the assessment of glaucomatous visual progression is found when PROGRESSOR, rather than standard clinical methods, is used. The optimum frequency of visual field testing is investigated: reducing the frequency of examinations from 3 per year to 1 per year results in failure to detect over half of the deteriorating test locations. A strong association is found between patient perception of visual disability and objectively measured damage and deterioration in glaucomatous visual fields even in mild to moderate glaucoma. Image processing techniques have previously been used to increase the reproducibility and predictability of automated visual field tests. These techniques are incorporated into PROGRESSOR. Results presented in this thesis indicate that these benefits are obtained without delayed detection of visual field progression. The PROGRESSOR software shows great potential in the detection and quantification of glaucomatous visual field deterioration. It promises to be an important part of the management of glaucoma patients in the future
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