Search results for "Contrast"
showing 10 items of 1162 documents
Refractive changes in nuclear, cortical and posterior subcapsular cataracts. Effect of the type and grade
2015
Purpose: To determine the effect of main morphological types and grades of age-related cataracts on refractive error. Methods: We measured 276 subjects with optical compensation prior to the development of cataract. We evaluated 224 eyes with nuclear cataract, 125 with cortical cataract, and 103 with posterior subcapsular (PSC) cataract classified with LOCSIII. We measured visual acuity (VA) with their spectacles and best-corrected visual acuity (BCVA) with chart in decimal scale to obtain the optimal compensation with cataract. We evaluated the differences between compensations. Results: A significant myopic shift was observed in nuclear cataract from low to mild grade (p = 0.031), the sam…
Optical and visual performance of diffractive intraocular lens implantation after myopic laser in situ keratomileusis
2008
To evaluate the optical and visual quality in eyes with diffractive intraocular lenses (IOLs) after myopic laser in situ keratomileusis (LASIK).Fernández-Vega Ophthalmological Institute, Oviedo, Spain.The best corrected visual acuity (BCVA [distance]) at 12.5%, 25.0%, and 100% contrasts under photopic and mesopic conditions; best distance-corrected near acuity; corneal total higher-order aberrations (HOAs); and optical quality by modulation transfer function (MTF) were measured after myopic LASIK in eyes with a spherical AcrySof ReSTOR SN60D3 IOL or an aspheric Acri.LISA 366D IOL and phakic eyes (control).Under photopic conditions at 100% contrast, the BCVA was 0.1 logMAR or better in all g…
Toric intraocular lens versus opposite clear corneal incisions to correct astigmatism in eyes having cataract surgery.
2009
To compare toric intraocular lens (IOL) implantation with paired opposite clear corneal incisions (OCCIs) for astigmatism correction in patients having cataract surgery.Ophthalmology Service, Donostia Hospital, San Sebastián, Spain.This randomized prospective clinical study comprised eyes with more than 1.00 diopter (D) of preexisting corneal astigmatism. One group had AcrySof toric IOL implantation and the other, paired 2.75 mm/3.20 mm OCCIs in the steep axis with spherical IOL implantation. Uncorrected (UCVA) and best corrected (BCVA) visual acuity, refraction, corneal and total higher-order aberrations (HOAs), photopic and mesopic contrast sensitivity, and toric IOL axis were measured 3 …
Comparison of iodinated contrast media for the assessment of atherosclerotic plaque attenuation values by CT coronary angiography: observations in an…
2013
Objective: To compare the influence of different iodinated contrast media with several dilutions on plaque attenuation in an ex vivo coronary model studied by multislice CT coronary angiography. Methods: In six ex vivo left anterior descending coronary arteries immersed in oil, CT (slices/collimation 64x0.625 mm, temporal resolution 210 ms, pitch 0.2) was performed after intracoronary injection of a saline solution, and solutions of a dimeric isosmolar contrast medium (Iodixanol 320 mgl ml(-1)) and a monomeric high-iodinated contrast medium (Iomeprol 400 mgl ml(-1)) with dilutions of 1/80 (low concentration), 1/50 (medium concentration), 1/40 (high concentration) and 1/20 (very high concent…
Computer-Aided Detection for Prostate Cancer Detection based on Multi-Parametric Magnetic Resonance Imaging
2017
International audience; Prostate cancer (CaP) is the second most diagnosed cancer in men all over the world. In the last decades, new imaging techniques based on magnetic resonance imaging (MRI) have been developed improving diagnosis. In practice, diagnosis is affected by multiple factors such as observer variability and visibility and complexity of the lesions. In this regard, computer-aided detection and diagnosis (CAD) systems are being designed to help radiologists in their clinical practice. We propose a CAD system taking advantage of all MRI modalities (i.e., T2-W-MRI, DCE-MRI, diffusion weighted (DW)-MRI, MRSI). The aim of this CAD system was to provide a probabilistic map of cancer…
Differentiation between acute and chronic myocardial infarction by means of texture analysis of late gadolinium enhancement and cine cardiac magnetic…
2017
[EN] The purpose of this study was to differentiate acute from chronic myocardial infarction using machine learning techniques and texture features extracted from cardiac magnetic resonance imaging (MRI). The study group comprised 22 cases with acute myocardial infarction (AMI) and 22 cases with chronic myocardial infarction (CMI). Cine and late gadolinium enhancement (LGE) MRI were analyzed independently to differentiate AMI from CMI. A total of 279 texture features were extracted from predefined regions of interest (ROIs): the infarcted area on LGE MRI, and the entire myocardium on cine MRI. Classification performance was evaluated by a nested cross-validation approach combining a feature…
Abnormal Myocardial Perfusion After Infarction in Patients With Persistent TIMI Grade-3 Flow. Only an Acute Phenomenon?
2007
Introduction and objectives It has been suggested that abnormal perfusion as derived from cardiovascular magnetic resonance imaging (CMR) is a transient dysfunction of microcirculation after myocardial infarction (MI) with TIMI 3 flow. We hypothesized that defects of myocardial perfusion may persist during the following months. Methods Forty-seven patients with MI and sustained TIMI 3 flow underwent intracoronary myocardial contrast echocardiography (MCE) 1 week and 6 months after infarction. Abnormal perfusion by MCE was regarded as >1 hypoperfused segment. Results At one week, 20 patients showed abnormal perfusion as derived from MCE. At six months 10 patients displayed chronic abnormal p…
Intermediate visual function with different multifocal intraocular lens models
2009
Purpose To compare visual acuity at different distances after bilateral implantation of 1 of 4 multifocal intraocular lenses (IOLs). Setting Fernandez-Vega Ophthalmological Institute, Oviedo, Spain. Methods This study evaluated consecutive patients who had bilateral implantation of a spherical multifocal IOL with a +4.00 diopter (D) addition (add) (AcrySof ReSTOR SN60D3) or an aspheric multifocal IOL with a +4.00 D add (AcrySof ReSTOR SN6AD3), +3.75 D add (Acri.LISA 366D), or +3.00 D add (AcrySof ReSTOR SN6AD1). Six months postoperatively, binocular measurement of corrected distance visual acuity (CDVA) at 4 m, corrected near visual acuity (CNVA) at 40 cm, and corrected intermediate visual …
Visual Acuity and Contrast Sensitivity in Eyes Implanted with Aspheric and Spherical Intraocular Lenses
2009
Purpose To compare visual acuity and contrast sensitivity (CS) in eyes implanted with aspheric and spherical intraocular lenses (IOLs) after cataract surgery. Design Randomized, prospective study. Participants Five hundred twenty-four eyes from 262 cataract surgery patients implanted with 2 IOL models: the AcrySof IQ (262 eyes) and AcrySof SN60AT (262 eyes; Alcon Laboratories, Fort Worth, TX). Methods High-contrast photopic best-corrected distance visual acuity (BCVA) and CS under photopic (85 cd/m 2 ) and mesopic (6 cd/m 2 ) conditions were measured. Pupil diameter was analyzed for distance vision under both lighting conditions. Follow-up was carried out for 6 months in all patients. Main …
Optical quality of the eye after lens replacement with a pseudoaccommodating intraocular lens
2007
To examine the optical quality of healthy presbyopic eyes before and after implantation of the pseudoaccommodating AcrySof ReSTOR Natural intraocular lens (IOL) (Alcon Laboratories) by measuring visual acuity and wavefront aberrations.University of Valencia, Fernández-Vega Ophthalmological Institute, Valencia, Spain.Monocular refraction and photopic distance (6 m) and near (0.33 m) visual acuities were determined before and after clear lens extraction with bilateral AcrySof ReSTOR Natural IOL implantation in 30 hyperopic eyes (+0.50 to +4.00 diopters [D]) of presbyopic patients with low astigmatism (or = 1.00 D). Postsurgical binocular visual acuity was measured over a range of effective di…