Cataract Surgery in Patients with Uveitis: Preoperative and Surgical Considerations

Cataract is one of the most frequent visual impairment complications of uveitis, accounting for up to 40% of the visual loss seen in these patients. In general, uveitis patients differ from the general cataract population in that they are younger and have a higher rate of comorbidities, however the rates of inflammatory sequelae vary markedly among uveitic entities. Cataract development may be influenced by the cause and duration of uveitis, the degree of inflammation control, and the use of corticosteroid therapy. Cataract surgery in patients with uveitis represents a serious challenge due to pre-existing ocular comorbidities that may limit the visual outcome and difficult the surgical procedure; the need for preoperative control of inflammation; and the efficacy of postoperative management to avoid immediate and late ocular complications. A detailed ophthalmologic exam prior to surgery is essential to know the status of pre-existing pathologic changes, adjust the medical therapy to achieve absolute control of inflammation, establish a surgical plan, and deliver an objective visual prognosis to the patient or the relatives. The key point to surgical success is the absolute control of inflammation, meaning no cells in the anterior chamber for at least 3 months prior to surgery. Today, minimally invasive phacoemulsification with acrylic foldable intraocular lens implantation is the standard of care for most patients with uveitis. It must be taken into consideration that higher rates of intraoperative and postoperative complications may occur. Vision-limiting pathology related to pre-existing uveitis complications are the major contributing factors for limited postoperative visual outcome

Beam hardening artifact reduction using dual energy computed tomography: implications for myocardial perfusion studies

Background: Myocardial perfusion computed tomography (CTP) using conventional single energy (SE) imaging is influenced by the presence of beam hardening artifacts (BHA), occasionally resembling perfusion defects and commonly observed at the left ventricular posterobasal wall (PB). We therefore sought to explore the ability of dual energy (DE) CTP to attenuate the presence of BHA. Methods: Consecutive patients without history of coronary artery disease who were referred for computed tomography coronary angiography due to atypical chest pain and a normal stress-rest SPECT and had absence or mild coronary atherosclerosis constituted the study population. The study group was acquired using DE and the control group using SE imaging. Results: Demographical characteristics were similar between groups, as well as the heart rate and the effective radiation dose. Myocardial signal density (SD) levels were evaluated in 280 basal segments among the DE group (140 PB segments for each energy level from 40 keV to 100 keV; and 140 reference segments), and in 40 basal segments (at the same locations) among the SE group. Among the DE group, myocardial SD levels and myocardial SD ratio evaluated at the reference segment were higher at low energy levels, with significantly lower SD levels at increasing energy levels. Myocardial signal-to-noise ratio was not significantly influenced by the energy level applied, although 70 keV was identified as the energy level with the best overall signal-to-noise ratio. Significant differences were identified between the PB segment and the reference segment among the lower energy levels, whereas at ≥ 70 keV myocardial SD levels were similar. Compared to DE reconstructions at the best energy level (70 keV), SE acquisitions showed no significant differences overall regarding myocardial SD levels among the reference segments. Conclusions: Beam hardening artifacts that influence the assessment of myocardial perfusion can be attenuated using DE at 70 keV or higher.Fil: Rodriguez Granillo, Gaston Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; Argentina. Diagnóstico Maipú; ArgentinaFil: Carrascosa, Patricia. Diagnóstico Maipú; ArgentinaFil: Cipriano, Silvia. Diagnóstico Maipú; ArgentinaFil: De Zan, Macarena. Diagnóstico Maipú; ArgentinaFil: Deviggiano, Alejandro. Diagnóstico Maipú; ArgentinaFil: Capunay, Carlos. Diagnóstico Maipú; ArgentinaFil: Cury, Ricardo C.. Miami Cardiac and Vascular Institute and Baptist Health; Estados Unido

Computation and visualization of Casimir forces in arbitrary geometries: non-monotonic lateral forces and failure of proximity-force approximations

We present a method of computing Casimir forces for arbitrary geometries, with any desired accuracy, that can directly exploit the efficiency of standard numerical-electromagnetism techniques. Using the simplest possible finite-difference implementation of this approach, we obtain both agreement with past results for cylinder-plate geometries, and also present results for new geometries. In particular, we examine a piston-like problem involving two dielectric and metallic squares sliding between two metallic walls, in two and three dimensions, respectively, and demonstrate non-additive and non-monotonic changes in the force due to these lateral walls.Comment: Accepted for publication in Physical Review Letters. (Expected publication: Vol. 99 (8) 2007

Thoracic aorta cardiac-cycle related dynamic changes assessed with a 256-slice CT scanner

Objective: The aim of our study was to demonstrate whether the dynamic changes previously documented at the ascending and abdominal aorta are replicated at the thoracic aorta. Methods and results: A consecutive series of thirty patients referred to our institution to undergo CT angiography of the thoracic aorta (CTA) constituted the study population. Patients with diffuse aortic atherosclerosis were excluded from the analysis. All studies were acquired with a 256-MDCT scanner and ECG-gating was performed in all cases. Two orthogonal imaging planes (maximal and minimal diameters) were obtained at three different levels of the descending thoracic aorta, using the distance from the left subclavian artery as proximal landmark: 10, 40, and 80 mm distance. The mean age was 58.9±15.7 years and 16 (53%) patients were male. Descending aorta measurements at 10, 40, and 80 mm distance from the left subclavian artery were all significantly larger within the systolic window (P<0.01 for all comparisons). Measurements of the maximal diameter were systematically larger than the minimal diameters among all aortic positions including ungated, systolic, and diastolic measurements (P<0.05 for all comparisons). Conclusions: The main finding of our pilot investigation was that the thoracic descending aorta undergoes significant conformational changes during the cardiac cycle, irrespective from the distance from the left subclavian artery.Fil: Carrascosa, Patricia. Diagnóstico Maipú; ArgentinaFil: Capuñay, Carlos. Diagnóstico Maipú; ArgentinaFil: Deviggiano, Alejandro. Diagnóstico Maipú; ArgentinaFil: Rodriguez Granillo, Gaston Alfredo. Diagnóstico Maipú; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sagarduy, María Inés. Diagnóstico Maipú; ArgentinaFil: Cortines, Patricio. Diagnóstico Maipú; ArgentinaFil: Carrascosa, Jorge. Diagnóstico Maipú; ArgentinaFil: Parodi, Juan C.. Sanatorio Trinidad; Argentin

Anterior-segment optical coherence tomography for the detection and therapeutic monitoring of corneal disorders

Background: Over recent years a revolutionary trend happened on imaging technologies to diagnose and monitor treatment of a varied group of ophthalmic pathologies. Recent reports have analyzed the microstructural changes of various ocular surface and corneal disorders, particularly ocular surface squamous neoplasia (OSSN) and keratoconus using anterior-segment optical coherence tomography (AS-OCT). Aim of this short communication is to elaborate on clinical applications AS-OCT for the detection and therapeutic monitoring of corneal disorders. Methods: We performed an English literature search without a time limit and intending to identify articles related to the AS-OCT applications in the detection and therapeutic monitoring of corneal disorders. The most relevant articles were selected.&nbsp; practical points of selected papers and advantages and disadvantages of AS-OCT were retrieved from them and summarized. Results:.Many records reported the AS-OCT applications for diagnosing many ocular surface disorders, the microstructural changes of different inflammatory, infectious, degenerative, and dystrophic corneal disorders. Its applications in identifying disease activity and therapeutic monitoring of various corneal pathologies, including stromal edema associated with angle-closure glaucoma, Fuchs endothelial dystrophy, infectious keratitis, and bullous keratopathy, are promising. The percentage of diagnostic sensitivity, specificity, and accuracy of artificial intelligence methodologies applied to AS-OCT imaging analysis today has reached 94% to 100%. Moreover, AS-OCT is very useful for analyzing the extension of scar and leukoma depth for surgical planning of partial or total corneal transplantation. Conclusions: There is a clear prospect for expanding application of corneal OCT imaging technology, a rapid, non-invasive, and now a promising lower-cost device, which is becoming an in-office standard-of-care tool for the assessment of different corneal and ocular surface pathologies. KEYWORDS anterior-segment optical coherence tomography, AS-OCT, ocular surface disorders, corneal disorders, ocular surface squamous neoplasia, OSSN, keratoconu

Human islet isolation and allotransplantation in 22 consecutive cases

This report provides our initial experience in islet isolation and intrahepatic allotransplantation in 21 patients. In group 1, 10 patients underwent combined liver-islet allotransplantation following upper-abdominal exenteration for cancer. In group 2, 4 patients received a combined liver-islet allograft for cirrhosis and diabetes. One patient had plasma C-peptide >3 pM and was therefore excluded from analysis. In group 3, 7 patients received 8 combined cadaveric kidney-islet grafts (one retransplant) for end-stage renal disease secondary to type 1 diabetes mellitus. The islets were separated by a modification of the automated method for human islet isolation and the preparations were infused into the portal vein. Immunosuppression was with FK506 (group 1) plus steroids (groups 2 and 3). Six patients in group 1 did not require insulin treatment for 5 to > 16 months. In groups 2 and 3 none of the patients became insulin-independent, although decreased insulin requirement and stabilization of diabetes were observed. Our results indicate that rejection is still a major factor limiting the clinical application of islet transplantation in patients with type 1 diabetes mellitus, although other factors such as steroid treatment may contribute to deteriorate islet engraftment and/or function. © 1992 by Williams and Wilkins

400%/W second harmonic conversion efficiency in 14μm\mathrm{14 \mu m}-diameter gallium phosphide-on-oxide resonators

Second harmonic conversion from 1550~nm to 775~nm with an efficiency of 400% W$^{-1}$ is demonstrated in a gallium phosphide (GaP) on oxide integrated photonic platform. The platform consists of doubly-resonant, phase-matched ring resonators with quality factors $Q \sim 10^4$, low mode volumes $V \sim 30 (\lambda/n)^3$, and high nonlinear mode overlaps. Measurements and simulations indicate that conversion efficiencies can be increased by a factor of 20 by improving the waveguide-cavity coupling to achieve critical coupling in current devices.Comment: 13 pages, 6 figure