Search results for "Sensor"
showing 10 items of 4594 documents
Combined effects of aging and a pro-diabetic diet on retinal function in a murine model of aging of the human eye
2009
; Purpose: Improvement of life expectancy and changes in the dietary behaviour of developed populations are accompanied with the prevalence of diabetes and age-related ocular pathologies. Aging of the retina is characterized by accumulation of lipids at the basement of the retinal pigment epithelium - Bruch’s membrane complex.Meanwhile increased oxidative stress is one of the features of aging and diabetes. A fructose-rich diet induces insulin resistance and hypertriglyceridemia, mimicking diabetes. The goal of our study was to evaluate the effects of a pro-diabetic fructose-enriched diet on the retinal function of the ApoB100,LDLR-/- mice, a murine model of aging of the human eye. Methods…
Effects of Superficial Keratectomy in Peripheral Hypertrophic Subepithelial Corneal Opacification on Front and Back Corneal Astigmatism
2020
To evaluate changes of anterior and posterior corneal astigmatism after superficial keratectomy in peripheral hypertrophic subepithelial corneal opacification (PHSCO). Patients with PHSCO, who had ...
Vacuoles in the Acrysof<sup>TM</sup> Intraocular Lens as Factor of the Presence of Serum in Aqueous Humor
2001
<i>Objective:</i> Acrysof™ (Alcon) foldable lenses (IOLs) have been shown to be highly biocompatible and exhibit a low incidence of posterior capsular opacification. However, minute vacuoles or ‘glistenings’ have been observed in some Acrysof IOLs. The clinical relevance of vacuole formation is presently unclear. To help clarify the influence of factors present under in vivo conditions on vacuole formation, the present experimental study examines the influence of aqueous humor components on the occurrence of vacuoles in Acrysof IOLs. <i>Methods:</i> A total of 12 sterile Acrysof IOLs (Alcon, MA60BM) were incubated at body temperature (37°C) for 3 or 6 months in anter…
Mapping symbols to sounds: electrophysiological correlates of the impaired reading process in dyslexia
2012
Dyslexic and control first-grade school children were compared in a Symbol-to-Sound matching test based on a non-linguistic audiovisual training which is known to have a remediating effect on dyslexia. Visual symbol patterns had to be matched with predicted sound patterns. Sounds incongruent with the corresponding visual symbol (thus not matching the prediction) elicited the N2b and P3a event-related potential (ERP) components relative to congruent sounds in control children. Their ERPs resembled the ERP effects previously reported for healthy adults with this paradigm. In dyslexic children, N2b onset latency was delayed and its amplitude significantly reduced over left hemisphere whereas P…
Early cortical processing of vection-inducing visual stimulation as measured by event-related brain potentials (ERP)
2019
Abstract Visual motion stimuli can induce the perception of self-motion in stationary observers (known as vection). In the present study, we investigated the sensory processing underlying vection by measuring the human event-related brain potentials (ERPs) elicited by the movement onset of a visual stimulus. We presented participants a visual stimulus consisting of alternating black-and-white vertical bars that moved in horizontal direction, creating the sensation of vection. The stimulus was presented on a screen that was divided into a central and a surrounding peripheral visual area. Both areas moved independently from each other, resulting in four different movement patterns: the periph…
Weighted Integration of Duration Information Across Visual and Auditory Modality Is Influenced by Modality-Specific Attention.
2021
We constantly integrate multiple types of information from different sensory modalities. Generally, such integration is influenced by the modality that we attend to. However, for duration perception, it has been shown that when duration information from visual and auditory modalities is integrated, the perceived duration of the visual stimulus leaned toward the duration of the auditory stimulus, irrespective of which modality was attended. In these studies, auditory dominance was assessed using visual and auditory stimuli with different durations whose timing of onset and offset would affect perception. In the present study, we aimed to investigate the effect of attention on duration integr…
Visual mismatch negativity for changes in orientation - a sensory memory-dependent response
2008
It remains unclear whether the mismatch negativity of event-related potentials (ERPs) in vision resembles its auditory counterpart in terms of memory relatedness. We recorded ERPs to visual bars in adult humans engaged in an auditory task. In one condition, a bar ('standard') repeated at 400- or 1100-ms non-stimulated intervals was rarely (P = 0.1) replaced by another bar of a different orientation ('deviant'). In the other condition (400-ms intervals), the occurrences of the standards were replaced by 10 (P = 0.1 each) bars of different orientations, including that of the deviant ('control-deviant'). Deviants shifted ERPs towards negative polarity relative to standards in occipital electro…
Maintenance of anticoagulant and antiplatelet agents for patients undergoing vitreoretinal surgery
2010
International audience; Purpose: To establish the prevalence of anticoagulant, aspirin, and clopidogrel use in patients undergoing vitreoretinal surgery, and to compare the outcome of peribulbar anesthesia between users and non‐users. Methods: We conducted a retrospective case series in one academic center between January and June 2009. We analyzed the chart of 239 eyes who underwent posterior segment surgery with peribulbar anesthesia. No changes in the anticoagulant regimen were made prior to surgery. We divided patients into 7 groups: group 1: patients with no anticoagulants and 6 groups defined according to the type of anticoagulant or antiplatelet medication. Results: 239 eyes (206 pat…
Role of the tear film in the optical quality of the human eye.
2007
This paper reviews recent studies of the role of the tear film in the optical quality of the eye. Recent investigations focus on the dynamics of the tear film after a blink and its important role in the optical quality of the eye. The results in this review were used in an attempt to understand the optical and visual impact of tear-film breakup in normal eyes and dry eyes. It was noted that patients with dry-eye syndrome have large optical aberrations compared with those in normal eyes, which may be the cause of blurry vision associated with the syndrome. In addition, instillation of artificial tears reduces optical aberrations and thus improves the optical quality of vision in these patien…
Mapping of the human visual cortex using image-guided transcranial magnetic stimulation
2002
We describe a protocol using transcranial magnetic stimulation (TMS) to systematically map the visual sensations induced by focal and non-invasive stimulation of the human occipital cortex. TMS is applied with a figure of eight coil to 28 positions arranged in a 2x2-cm grid over the occipital area. A digitizing tablet connected to a PC computer running customized software, and audio and video recording are used for detailed and accurate data collection and analysis of evoked phosphenes. A frameless image-guided neuronavigational device is used to describe the position of the actual sites of the stimulation coils relative to the cortical surface. Our results show that TMS is able to elicit p…