Search results for " Structures"
showing 10 items of 4162 documents
Analysis of the possible benefits of aspheric intraocular lenses: review of the literature.
2008
We reviewed recently published studies that analyzed the visual and optical quality in eyes with different spherical and aspheric intraocular lenses (IOLs). Recent studies focused on visual quality metrics, such as visual acuity and contrast sensitivity, under photopic and mesopic lighting conditions and optical metrics, such as wavefront aberrations, especially spherical aberration. The results in this review were used in an attempt to understand whether there is a visual and/or optical benefit of implanting aspheric IOLs over implanting spherical IOLs.
<title>Estimation of stereovision in conditions of blurring simulation</title>
2005
The aim of this study was to evaluate the simulation of eye pathologies, such as amblyopia and cataracts, to estimate the stereovision in artificial conditions, and to compare the results on the stereothreshold obtained in artificial and real- pathologic conditions. Characteristic of the above-mentioned real-life forms of a reduced vision is a blurred image in one of the eyes. The blurring was simulated by (i) defocusing, (ii) blurred stimuli on the screen, and (iii) occluding of an eye with PLZT or PDLC plates. When comparing the methods, two parameters were used: the subject's visual acuity and the modulation depth of the image. The eye occluder method appeared to systematically provide h…
Changes in visual function and retinal structure in the progression of Alzheimer's disease
2019
Background Alzheimer's Disease (AD) can cause degeneration in the retina and optic nerve either directly, as a result of amyloid beta deposits, or secondarily, as a result of the degradation of the visual cortex. These effects raise the possibility that tracking ophthalmologic changes in the retina can be used to assess neurodegeneration in AD. This study aimed to detect retinal changes and associated functional changes in three groups of patients consisting of AD patients with mild disease, AD patients with moderate disease and healthy controls by using non-invasive psychophysical ophthalmological tests and optical coherence tomography (OCT). Methods We included 39 patients with mild AD, 2…
Visual performance with multifocal intraocular lenses
2004
Abstract Objective To evaluate distance and near visual performance under bright (photopic) and dim (mesopic) conditions in patients who had undergone uncomplicated cataract extraction with multifocal or monofocal intraocular lens (IOL) implantation. Design Prospective, nonrandomized, masked, comparative, observational case series. Participants Thirty-two eyes of 32 patients after zonal-progressive multifocal IOL implantation (Allergan Medical Optics Array SA-40N) and 32 eyes of 32 age-matched patients after monofocal IOL implantation (Allergan Medical Optics SI-40NB). Intervention All eyes underwent phacoemulsification and IOL implantation. Main outcome measures At 18 months after surgery,…
Effect of specialized applications on the visual functions of amblyopic eye in Latvian children
2021
The classical treatment option of amblyopia is occlusions of non-amblyopic eye. The newest methods involve specialized computer and phone games, applications that involve both eyes in visual processing during treatment as well as stimulate binocularity. The aim of the work was to assess the efficiency of specialized phone application ‘Duovision’ in the treatment of amblyopia in preschool-age children. There were 30 participants (5-8 years old): 16 participants had occlusion therapy; 14 participants played the specialized phone application Duovision®. The visual acuity of amblyopic eye, as well as stereopsis was evaluated at near and far distances before the treatment, 2 and 4 months after t…
Effect of Light Scattering Simulation in the Eye on Different Color Stimuli Perception
2008
One of the factors which influences visual functions is intraocular light scattering. To assess the effect of light scattering and stimulus color on visual functions, visual acuity and retinal straylight were measured with and without light scattering occluder. For visual acuity measurements black Landolt optotypes on red, green and blue background were used. Retinal straylight was measured with a direct compensation method using the same colors stimuli. For one subject straylight was measured with 5 different light scattering levels of eye occluder.
Objective and subjective evaluation of photic phenomena after monofocal and multifocal intraocular lens implantation11The authors have no commercial …
1999
Abstract Objective To objectively measure and compare halo, flicker, and glare disability in pseudophakic eyes with monofocal (MONO) and multifocal (MULTI) intraocular lenses (IOLs) with respect to the influence of corneal surface quality, astigmatism, and age. Design Prospective case series. Participants This clinical trial involved 28 eyes of 28 patients after small-incision cataract surgery with a MONO silicone IOL and 28 eyes of 28 patients with zonal-progressive silicone IOL. Intervention A computer program objectively determined halo, glare, and flicker. Corneal surface quality and astigmatism were measured using computerized videokeratography. Ray-tracing analysis was performed based…
Processing of audiovisual associations in the human brain: dependency on expectations and rule complexity
2012
In order to respond to environmental changes appropriately, the human brain must not only be able to detect environmental changes but also to form expectations of forthcoming events. The events in the external environment often have a number of multisensory features such as pitch and form. For integrated percepts of objects and events, crossmodal processing, and crossmodally induced expectations of forthcoming events are needed. The aim of the present study was to determine whether the expectations created by visual stimuli can modulate the deviance detection in the auditory modality, as reflected by auditory event-related potentials (ERPs). Additionally, it was studied whether the complexi…
Colour vision experimental studies in teaching of optometry
2005
Following aspects related to human colour vision are included in experimental lessons for optometry students of University of Latvia. Characteristics of coloured stimuli (emitting and reflective), determination their coordinates in different colour spaces. Objective characteristics of transmitting of colour stimuli through the optical system of eye together with various types of appliances (lenses, prisms, Fresnel prisms). Psychophysical determination of mono- and polychromatic stimuli perception taking into account physiology of eye, retinal colour photoreceptor topography and spectral sensitivity, spatial and temporal characteristics of retinal receptive fields. Ergonomics of visual perce…
Multivariate EEG spectral analysis evidences the functional link between motor and visual cortex during integrative sensorimotor tasks
2012
The identification of the networks connecting brain areas and the understanding of their role in executing complex tasks is a crucial issue in cognitive neuroscience. In this study, specific visuomotor tasks were devised to reveal the functional network underlying the cooperation process between visual and motor regions. Electroencephalography (EEG) data were recorded from twelve healthy subjects during a combined visuomotor task, which integrated precise grip motor commands with sensory visual feedback (VM). This condition was compared with control tasks involving pure motor action (M), pure visual perception (V) and visuomotor performance without feedback (V + M). Multivariate parametric …