Search results for "structures"
showing 10 items of 4815 documents
Cilioretinal artery occlusion.
2015
Background: The aim of this study was to evaluate characteristic findings and functional outcome of this rare type of retinal vascular occlusion in a large patient series. Patients and Methods: A retrospective chart review of all patients with a cilioretinal artery obstruction (CAO) seen at the University Eye Clinic Mainz (Germany) over a ten-year period between 1/1999 and 12/2008 was undertaken. The mean follow-up amounted to 42 months. Results: Thirty-three eyes were diagnosed with CAO. Three distinct groups were differentiated: (i) isolated CAO in 20/33 eyes; visual outcome achieving 20/50 in 17/20 eyes; (ii) CAO combined with central retinal vein occlusion in 9/33 eyes; visual outcome a…
Optical coherence tomography-based retinal vessel analysis for the evaluation of hypertensive vasculopathy
2013
Purpose Evaluation of retinal vessels in cardiovascular disease traditionally relies upon funduscopy, but more recently digital photo analysis has expanded the spectrum. As spectral domain optical coherence tomography (OCT) allows an in-vivo assessment of retinal tissue and its vessels on a histological scale, our study aimed at using this tool for the analysis of the retinal vasculature. Methods Circumferential peripapillary OCT scans (3DOCT-2000; Topcon Inc., Tokyo, Japan), with centration on the optic nerve head, were taken from 20 eyes (20 participants) with normal blood pressure and 20 eyes (20 participants) with arterial hypertension above 120 mmHg (mean blood pressure). The diameter …
Oculovestibular interactions under microgravity.
1993
On a space mission in March 1992 a set of experiments were performed aimed at clarifying the interaction between visual, proprioceptive and vestibular inputs to the equilibrium system. Using the VESTA goggle facility from the European Space Agency we investigated the effect of pure neck receptor stimulation on eye position as measured by the flash afterimage method and on perception of a head-fixed luminous line in space. Space vestibular adaptation processes were measured by rotating pattern perception during prescribed head movements. It was found that static ocular counterrotation does not occur under micro gravity conditions. This result suggests that the neck receptors apparently do no…
Real-time control for transscleral cyclophotocoagulation.
1998
• Background: In transscleral cyclophotocoagulation, the surgeon cannot directly observe the applied laser effects. Overdosage, possibly resulting in unwanted pop effects, or underdosage with no therapeutic effect therefore often occur. • Method and materials: Laser radiation passing through the sclera and ciliary body is partly reflected from the fundus and can be monitored from outside the eye by a detector system. Since all other parameters influencing the intensity of the recorded radiation are constant in time during one laser exposure, the time dependence of this radiation directly reflects the change of transmission of the treated tissue. The laser exposure therefore can be stopped b…
Fixation suppression of optokinetic nystagmus modulates cortical visual-vestibular interaction.
2005
Water activation positron emission tomography and statistical group analysis were used to evaluate differences in activation-deactivation patterns during small-field visual motion stimulation, eliciting rightward optokinetic nystagmus and its fixation suppression in 12 healthy volunteers. Bilateral patterns of activation in the visual cortex, including the motion-sensitive area MT/V5, and deactivations in an assembly of vestibular areas (posterior insula, thalamus, anterior cingulate gyrus) during optokinetic nystagmus was markedly diminished or totally absent during its fixation suppression. This finding agrees with the concept of a reciprocal inhibitory interaction between the visual-opto…
Subclinical optic neuropathy in Fabry disease.
2009
Fabry disease is a rare X-linked lysosomal storage disorder, caused by the deficiency of alpha-galactosidase A. Ophthalmic features comprise a cornea verticillata, conjunctival aneurysms, tortuous conjunctival and/or retinal vessels, and anterior and posterior subcapsular cataracts. The issue of a possible subclinical optic neuropathy in Fabry disease has been raised recently. In this pilot study, we looked for signs of optic neuropathy in our cohort of Fabry patients.Thirty-one Fabry patients (15 male, 16 female, mean age 34 years) underwent an ophthalmological investigation consisting of assessment of best corrected visual acuity, slit lamp investigation, testing of pupillary reaction, fu…
Hemispatial neglect reflected on visual memory
2011
PURPOSE Recent studies of hemispatial neglect have revealed both lateralized and nonlateralized attention mechanisms contributing to the syndrome. In addition, neglect patients show impaired spatial working memory and diminished working memory capacity. The aim of this study was to investigate, how neglect would be reflected in their performances in commonly used clinical visual memory tests. METHODS Twelve patients with right hemisphere lesions and left neglect and twelve matched controls were assessed with the Behavioural Inattention Test, the visual reproduction of the WMS-R, the object memory test, the Rey figure test and the list learning test. Visuo-spatial span was explored with the …
Tactile perceptual processes and their relationship to medically unexplained symptoms and health anxiety
2011
Abstract Objective The Somatic Signal Detection Task (SSDT; Lloyd, Manson, Brown and Poliakoff, 2008) is an innovative paradigm to study perceptual processes related to physical symptoms. It allows examining touch illusions as a laboratory analog of medically unexplained symptoms (MUS) according to the cognitive model of MUS proposed by Brown (2004). The present study compared psychopathologic measures of MUS and health anxiety with SSDT parameters. Furthermore, we aimed to define a reliable measurement of tactile perception threshold. Methods 67 participants of a student population reported whether they detected tactile stimuli at their fingertip which were presented in half of the test tr…
Multisensorial Perception in Chronic Migraine and the Role of Medication Overuse.
2020
Multisensory processing can be assessed by measuring susceptibility to crossmodal illusions such as the Sound-Induced Flash Illusion (SIFI). When a single flash is accompanied by 2 or more beeps, it is perceived as multiple flashes (fission illusion); conversely, a fusion illusion is experienced when more flashes are matched with a single beep, leading to the perception of a single flash. Such illusory perceptions are associated to crossmodal changes in visual cortical excitability. Indeed, increasing occipital cortical excitability, by means of transcranial electrical currents, disrupts the SIFI (ie, fission illusion). Similarly, a reduced fission illusion was shown in patients with episod…
Long-term sensorimotor and therapeutical effects of a mild regime of prism adaptation in spatial neglect
2015
International audience; Spatial neglect (SN) is commonly associated with poor functional outcome. Adaptation to a rightward optical deviation of vision has been shown to benefit to SN rehabilitation. The neurophysiological foundations and the optimal modalities of prism adaptation (PA) therapy however remain to be validated. This study is aimed at exploring the long-term sensory-motor, cognitive and functional effects produced by weekly PA sessions over a period of four weeks. A double-blind, monocentric randomized and controlled trial (RCT) was carried out. Twenty patients with left SN secondary to stroke were included, 10 in the “prism” group and 10 in the “control” group. The sensory-mot…