Search results for "Contrast"
showing 10 items of 1162 documents
Visual acuity and contrast sensitivity screening with a new iPad application
2016
We present a new iPad application (app) for a fast assessment of Visual Acuity (VA) and Contrast Sensitivity (CS) whose reliability and agreement was evaluated versus a commercial screening device (Optec 6500). The measurement of VA was programmed in the app in accordance with the Amblyopia Treatment Study protocol. The CS was measured with sinusoidal gratings of four different spatial frequencies: 3, 6, 12 and 18 cpd at the same contrast values of the Functional Acuity Contrast Test (FACT) included in the Optec 6500. Forty-five healthy subjects with monocular corrected visual acuities better than 0.2 logMAR participated in the agreement study. Bland-Altman analyses were performed to assess…
Impact of the pupil size – central optical zone diameter relationship on visual performance in aspheric multifocal contact lenses
2020
Abstract Purpose To determine the impact of different central optical zone diameters (COZDs), obtained from pupil size, on the visual performance of presbyopic subjects fitted with centre-distance simultaneous-image multifocal contact lenses (SIMCLs). Methods Thirty-two presbyopic volunteers, between 45–58 years of age, participated in this prospective, controlled, double-blind study. Subjects were fitted with 5 centre-distance SIMCLs of variable COZD, determined from the measurement of pupil size under photopic light conditions and corresponding to 60, 70, 80, 90 and 100 % of pupil diameter. Subjects visual performance was evaluated through the measurement of distance, intermediate and nea…
Effect of Varying Levels of Glare on Contrast Sensitivity Measurements of Young Healthy Individuals Under Photopic and Mesopic Vision
2018
Contrast sensitivity (CS), the ability to detect small spatial changes of luminance, is a fundamental aspect of vision. However, while visual acuity is commonly measured in eye clinics, CS is often not assessed. At issue is that tests of CS are not highly standardized in the field and that, in many cases, optotypes used are not sensitive enough to measure graduations of performance and visual abilities within the normal range. Here, in order to develop more sensitive measures of CS, we examined how CS is affected by different combinations of glare and ambient lighting in young healthy participants. We found that low levels of glare have a relatively small impact on vision under both photopi…
Reading ability with 3 multifocal intraocular lens models.
2006
Purpose To prospectively evaluate reading performance with of 3 types of multifocal intraocular lenses (IOLs) under different lighting conditions based on reading acuity and reading speed tests. Setting Augenklinik, Bad Hersfeld, Germany. Methods This randomized study comprised 60 cataract patients (120 eyes) randomly assigned to receive an SA40N IOL (AMO) (Group 1, 20 patients), Tecnis ZM001 IOL (AMO) (Group 2, 20 patients), or AcrySof ReSTOR SA60D3 IOL (Alcon) (Group 3, 20 patients). Pupil size and reading ability at near (visual acuity, reading speed) without correction, with best distance correction, and with best near correction were assessed 6 weeks postoperatively under low-light con…
The Impact on Vision of Aspheric to Spherical Monofocal Intraocular Lenses in Cataract Surgery
2013
Purpose To provide a summary of the impact on vision of an aspheric intraocular lens (IOL) compared with a spherical IOL in cataract surgery. Design Systematic review with meta-analysis. Participants Patients from published randomized controlled trials (RCTs) of cataract surgery with aspheric compared with spherical monofocal IOL implantation. Methods We systematically searched the peer-reviewed literature in MEDLINE, EMBASE, Web of Science, BIOSIS, and the Cochrane Library according to the Cochrane Collaboration method to identify relevant RCTs. The inclusion criteria were RCTs on cataract surgery comparing the use of aspheric versus spherical IOL implantation that assessed visual acuity, …
Visual and postural eye-height information is flexibly coupled in the perception of virtual environments.
2021
We conducted two experiments to investigate how observers integrate postural and visual eye-height information when estimating the layout of interior space. In Experiment 1, we varied postural and visual eye-height information independently of each other in a virtual-reality setup. Observers estimated the width, depth, and height of simulated rooms. All dimensions were perceived as larger when the virtual visual eye-height corresponded to sitting on the floor as compared with standing upright. In contrast, the estimates remained widely unaffected by the observer's physical posture (likewise sitting vs. standing). In Experiment 2, we studied effects of the viewing condition (real vs. virtual…
Whole-body magnetic resonance imaging (WB-MRI) in oncology: an Italian survey.
2019
Purpose: To perform a survey among all members of the Italian Society of Medical and Interventional Radiology (SIRM) to assess how whole-body MRI (WB-MRI) is performed in oncologic patients in Italy. Methods: On March 2019, we administered an online poll to all SIRM members about their use of WB-MRI in 2018 asking 15 questions regarding oncologic indications, imaging protocol, use of contrast media, experience in WB-MRI, duration of scan time and reporting time. Results: Forty-eight members participated to the survey. WB-MRIs/total MRIs ratio was 1%. Lymphoma was the most common indication (17/48, 35%), followed by myeloma and prostate cancer, with these three tumors representing the most c…
Implant-specific follow-up imaging of treated intracranial aneurysms: TOF-MRA vs. metal artifact reduced intravenous flat panel computed tomography a…
2017
Aim To compare the diagnostic quality of time-of-flight magnetic resonance angiography (TOF-MRA) and metal-artefact-reduction (MAR) flat-panel-detector computed tomography angiography (FPCTA) and to determine the imaging technique best suited for evaluation endovascular and surgically treated aneurysms. Methods The image quality of TOF-MRA and MAR-FPCTA of 44 intracranial implants (coiling: n= 20; clipping: n= 15; coiling + stenting: n= 9) in a patient cohort of 25 was evaluated by two independent readers. Images obtained using MAR-FPCTA (20 second scan time, 496 projections, intravenous contrast medium administration; Artis Zee, Siemens Healthcare, Forchheim) were compared with TOF-MRA-ima…
Ösophagusresektion bei unspezifischer Motilitätsstörung der Speiseröhre - Bedeutung der neuropathologischen Befunde
2005
A 47-year-old patient presented with a history of dysphagia for solid food for almost 10 years and weight loss of more than 50 kg. Non-resecting surgical as well as endoscopic procedures (laparoscopic cardiomyotomy with secondary antireflux operations, balloon dilation, Botulinum-toxin injection) were without success. A barium esophagogram showed a confinement of the distal esophagus with a filiform passage of the contrast medium and undigested food in the prestenotic dilated esophageal corpus. Manometry displayed a hypertensive lower esophageal sphincter with a resting pressure of 43.8 mmHg - although completely relaxing. The tubular esophagus was aperistaltic with 100 % simultaneous and r…
Vaccination Coverage Increase among Adolescent and Young Adults of the Palermo District (Italy) as a Result of a Public Health Strategy to Contrast a…
2018
During summer 2016 in the District of Palermo, Italy, the rapid succession of four cases of invasive meningococcal disease among young adults, with one death, have had an extraordinary emphasis by Local and National mass media. The resultant “epidemic of panic” among general population overloaded vaccination Units of the Palermo District during following months. Strategies implemented by Sicilian and Local Public Health Authorities to counteract “meningitis fear” were: a) extension of active and free of charge anti-meningococcal tetravalent vaccination from age class 12–18 to 12–30 years old; b) implementation of vaccination units …