Search results for "VISION"
showing 10 items of 5066 documents
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…
Is Homelessness a Risk Factor for Eye Disease?
2005
<i>Background:</i> There is general agreement on the presence of a correlation between poverty and impaired health. However, only scarce data are available on whether this also applies to the incidence of eye disease. The present study was carried out to evaluate the prevalence of ocular disease in homeless people in Germany. <i>Methods:</i> 107 homeless people (97 male, 10 female; mean age 49 years, range 18–81 years) treated in specialised social service institutions were investigated prospectively according to a standardised ophthalmological screening protocol. This comprised visual acuity, assessment of pupillary light reaction, intra-ocular pressure, slit lamp e…
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…
Isthmic Spondylolisthesis is Associated with Less Revisions for Adjacent Segment Disease After Lumbar Spine Fusion Than Degenerative Spinal Condition…
2021
Objective: We aim to compare the rate of revisions for adjacent segment disease (ASD) after lumbar spine fusion (LSF) surgery between patients with isthmic spondylolisthesis (IS) and degenerative lumbar spine disorders (DLSD). Summary of Background Data: ASD is a major reason for late reoperations after LSF surgery. Several risk factors are linked to the progression of ASD, but the understanding of the underlying mechanisms is imperfect. If IS infrequently becomes complicated with ASD, it would emphasize the role of the ongoing degenerative process in spine in the development of ASD. Methods: 365 consecutive patients that underwent elective LSF surgery were followed up for an average of 9.7…
Poly(adenosine diphosphate-ribose) polymerase in quail oviduct. Changes during estrogen and progesterone induction
1974
Abstract The activities of the following enzymes have been determined in nuclei of quail oviducts in response to exogenous stimulation of the birds with diethylstilbestrol, used as an estrogen analogue and progesterone: DNA dependent DNA polymerase, DNA dependent RNA polymerase I and II and poly(adenosine diphosphate-ribose) [=poly(ADP-Rib)] polymerase. During primary stimulation with the estrogen analogue the activities of the four DNA dependent polymerases increase to about the same degree. Upon withdrawal of the hormones the levels of the enzymes drop to values known from nuclei from unstimulated quail oviducts. The secondary stimulation with the estrogen analogue causes a significant in…
Signaling through BMPR-IA regulates quiescence and long-term activity of neural stem cells in the adult hippocampus.
2010
SummaryNeural stem cells (NSCs) in the adult hippocampus divide infrequently, and the molecules that modulate their quiescence are largely unknown. Here, we show that bone morphogenetic protein (BMP) signaling is active in hippocampal NSCs, downstream of BMPR-IA. BMPs reversibly diminish proliferation of cultured NSCs while maintaining their undifferentiated state. In vivo, acute blockade of BMP signaling in the hippocampus by intracerebral infusion of Noggin first recruits quiescent NSCs into the cycle and increases neurogenesis; subsequently, it leads to decreased stem cell division and depletion of precursors and newborn neurons. Consistently, selective ablation of Bmpr1a in hippocampal …
Use in clinical practice of an automated screening method of diabetic retinopathy that can be derived using a diagnostic artificial intelligence syst…
2020
Abstract Background and Objective To compare the diagnostic performance of an autonomous diagnostic artificial intelligence (AI) system for the diagnosis of derivable diabetic retinopathy (RDR) with manual classification. Materials and Methods Patients with type 1 and type 2 diabetes participated in a diabetic retinopathy (RD) screening program between 2011–2012. 2 images of each eye were collected. Unidentifiable retinal images were obtained, one centered on the disc and one on the fovea. The exams were classified with th e autonomous AI system and manually by anonymous ophthalmologists. The results of the AI system and manual classification were compared in terms of sensitivity and specif…
Stereoscopic Viewing Enhances Visually Induced Motion Sickness but Sound Does Not
2012
Optic flow in visual displays or virtual environments often induces motion sickness (MS). We conducted two studies to analyze the effects of stereopsis, background sound, and realism (video vs. simulation) on the severity of MS and related feelings of immersion and vection. In Experiment 1, 79 participants watched either a 15-min-long video clip taken during a real roller coaster ride, or a precise simulation of the same ride. Additionally, half of the participants watched the movie in 2D, and the other half in 3D. MS was measured using the Simulator Sickness Questionnaire (SSQ) and the Fast Motion Sickness Scale (FMS). Results showed a significant interaction for both variables, indicatin…
Spectral decomposition of RR-variability obtained by an open loop parametric model for the diagnosis of neuromediate syncope
2002
The role of the cardiovascular regulatory mechanism in patients with neuromediate syncope (NS) is poorly understood. The aim of this study was to accomplish continuous non-invasive analysis of the baroreflex mechanism in patients during a head-tip tilt-table test (HTT) using an open-loop autoregressive model with exogenous input. The model describes the causal dependence of the RR interval on the systolic arterial pressure (SAP) variability. Thus, RR variability results as the linear composition of SAP-dependent (Pdep) and SAP-independent parts of the RR power (P). Further, the model allows the estimation of the baroreflex gain using the modulus of the transfer function (G) from SAP to RR i…