AIMS: Visual acuity determination is an important task in ophthalmology and optometry practices. Visual acuity can be examined objectively or subjectively. The objective examination method, sVEP, allows for quick objective measurements of patient's visual acuity. Previous studies have not demonstrated the repeatability of this objective sVEP method. This study aims to evaluate the sVEP method and compare it to a subjective method. METHODS AND RESULTS: The sample was divided into two groups. For the first group, visual acuity was measured with sVEP and Snellen methods on only one patient twelve times. In the second group, visual acuity was measured twice with sVEP followed twice with the Snellen method with Landolt's rings and logMAR modification on 32 non-pathological patients. Results showed significant differences between average values of visual acuity obtained with both methods (sVEP and Snellen) in both samples (T-test, P < 0.01; Wilcoxon test, P = 0.02 in second group). In the second group, significant correlations between repeated sVEP measurements (Spearman test, P < 0.05, r = 0.69) were found but no significant correlation between average sVEP measurement and average Snellen measurement (Spearman test, P > 0.05, r = 0.15) was found. CONCLUSION: Objective measurement of visual acuity with sVEP is a valid and reliable method, but is recommended only when it is not possible to use a subjective method for measuring visual acuity, e.g. children, patients with mental retardation or simulating/dissimulating patients.

• Klíčová slova
• ETDRS chart, Snellen chart, electrophysiological methods, visual acuity, visual evoked potentials,
• MeSH
• dospělí MeSH
• elektrody MeSH
• lidé MeSH
• mladý dospělý MeSH
• osvětlení MeSH
• zraková ostrost fyziologie   MeSH
• zrakové evokované potenciály fyziologie   MeSH
• zrakové testy metody   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

PURPOSE: The purpose of the article is to present the history and current status of visual cortical neuroprostheses, and to present a new method of stimulating intact visual cortex cells. METHODS: This paper contains an overview of the history and current status of visual cortex stimulation in severe visual impairment, but also highlights its shortcomings. These include mainly the stimulation of currently damaged cortical cells over a small area and, from a morphological point of view, possible damage to the stimulated neurons by the electrodes and their encapsulation by gliotic tissue. RESULTS: The paper also presents a proposal for a new technology of image processing and its transformation into a form of non-invasive transcranial stimulation of undamaged parts of the brain, which is protected by a national and international patent. CONCLUSION: The paper presents a comprehensive review of the current options for compensating for lost vision at the level of the cerebral cortex and a proposal for a new non-invasive method of stimulating the functional neurons of the visual cortex.

• Klíčová slova
• visual neuroprosthesis, cortical visual centers, transcranial stimulation,
• MeSH
• lidé MeSH
• mozek * fyziologie   MeSH
• neurony MeSH
• poruchy zraku MeSH
• zrak MeSH
• zrakové korové centrum * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• systematický přehled MeSH

This article is dedicated to main information about visual field, monocular and binocular ranges of visual field including their defects. Visual field loss may occur to disease of the eye, optic nerve or brain. Typical changes are present at glaucoma and macular degeneration. Visual pathway is also mentioned. The basic medical examinations of visual fields are Amsler grid, kinetic and static perimetry and the other. Newer method is microperimetry which detects the changes directly on the retina. The aim of this poster is importance and determination of visual field as a preventive ophthalmologic and optometric examination.

• MeSH
• lidé MeSH
• testy zrakového pole MeSH
• zraková pole * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

We have studied the visual system of subterranean mole-rats of the rodent family Bathyergidae, for which light and vision seem of little importance. The eye diameter varies between 3.5mm in Bathyergus suillus and 1.3mm in Heterocephalus glaber. The small superficial eyes have features typical of sighted animals (clear optics, well-developed pupil and well-organized retina) and appear suited for proper image formation. The retinae are rod-dominated but possess rather high cone proportions of about 10%. The total number of retinal ganglion cells and optic nerve fibres ranges between 6000 in Bathyergus suillus and 2100 in Heliophobius argenteocinereus. Visual acuity (estimated from counts of peak ganglion cell density and axial length of the eye) is low, ranging between 0.3 and 0.5 cycles/degree. The retina projects to all the visual structures described in surface-dwelling sighted rodents. The suprachiasmatic nucleus is large and receives bilateral retinal input. All other visual nuclei are reduced in size and receive almost exclusively contralateral retinal projections of varying magnitude. The primary visual cortex is small and, in comparison to other rodents, displaced laterally. In conclusion, the African mole-rats possess relatively well-developed functional visual subsystems involved in photoperiodicity, form and brightness discrimination. In contrast, visual subsystems involved in coordination of visuomotor reflexes are severely reduced. This pattern suggests the retention of basic visual capabilities. Residual vision may enable subterranean mammals to localize breaches in the burrows that let in light thus providing a cue to enable mole-rats to reseal such entry points and to prevent entry of predators.

• MeSH
• colliculus superior anatomie a histologie   MeSH
• jádra thalamu MeSH
• metathalamus MeSH
• mikroftalmičtí podzemní hlodavci MeSH
• nucleus suprachiasmaticus MeSH
• retina anatomie a histologie   MeSH
• zrakové dráhy anatomie a histologie   MeSH
• zrakové korové centrum anatomie a histologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

AIMS: The aim of the study was to determine the limits of the far nasal part of the visual field. MATERIAL AND METHODS: Visual field examination was performed in 15 healthy subjects (30 eyes), specifically nine women aged 20-43 years and six men aged 22-35 years. All eyes were found to have physiological ocular findings and visual acuity of 1.0 with correction less than or equal to 3 diopters. The visual field was examined with a Medmont M700 instrument by shifting the fixation point 40 degrees temporally and simultaneously turning the head nasally, with a spatial accommodation program. A total of 89 examination points were included using flicker stimuli. RESULTS: The far nasal limit of the visual field reached 100° in 13.3% of eyes, 105° in 20% of eyes and up to 110° in 66.7% of eyes. CONCLUSION: The limit of the far nasal part of the field of vision reached 100-110 degrees (when nose shielding was eliminated).

• Klíčová slova
• visual field, enhanced perimetry, nasal range of visual field, perimetry, visual field,
• MeSH
• akomodace oka MeSH
• lidé MeSH
• testy zrakového pole * MeSH
• zraková ostrost MeSH
• zraková pole * MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Standard pattern-reversal visual evoked potentials (VEPs) and motion-onset VEPs (M-VEPs) were tested in 19 dyslexics and 19 normal readers aged 7-13 years in order to evaluate the feasibility of M-VEPs for the objective diagnostics of a visual subtype of dyslexia, in which a dysfunction of the magnocellular subsystem/dorsal stream of the visual pathway is suspected. The set of VEPs consisted of the pattern-reversal VEPs with check sizes of 20', two types of translational motion (with low and high contrast) and two types of radial motion (in the full field or the periphery). While the P100 peak parameters in pattern-reversal VEPs did not differ between the group of dyslexics and controls, the group of dyslexics displayed significantly longer N2 latencies in all types of M-VEPs. Abnormal N2 latencies were found in 35-56% of dyslexics in different types of M-VEPs, with translational motion with high contrast being the most sensitive stimulation. A receiver operating characteristic analysis showed that the latencies of M-VEPs displayed higher discrimination potential than M-VEPs amplitudes. The study confirms a "magnocellular pathway/dorsal stream deficit" in approximately half of dyslexics.

• Klíčová slova
• Children, Dorsal stream deficit, Dyslexia, Magnocellular system deficit, Motion-onset VEPs, Visual evoked potentials (VEPs),
• MeSH
• dítě MeSH
• dyslexie patofyziologie   MeSH
• lidé MeSH
• mladiství MeSH
• senzorické prahy fyziologie   MeSH
• studie případů a kontrol MeSH
• vnímání pohybu fyziologie   MeSH
• zrakové dráhy patofyziologie   MeSH
• zrakové evokované potenciály fyziologie   MeSH
• zrakové korové centrum fyziologie   MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

The purpose of this study is to provide an overview of the replacements used in lost vision in the form of the bionic eye, to show their deficiencies and outline other possibilities for non-invasive stimulation of functional areas of the visual cortex. The review highlights the damage not only to the primary altered cellular structures, but also to all other horizontally and vertically localised structures. Based on the results of a large number of functional magnetic resonance imaging and electrophysiological methods, the authors focus on the pathology of the entire visual pathway in pigmentary retinopathy (PR) and age-related macular degeneration (AMD). This study provides a recent overview of the possible systems used to replace lost vision. These range from stimulation with intraocular implants, through stimulation of the optic nerve and lateral geniculate nucleus to the visual cortex. The second part deals with the design of image processing technology and its transformation into the form of transcranial stimulation of undamaged parts of the brain, which is protected by a patent. This is comprehensive overview of the current possibilities of replacement of lost vision and a proposal for a new non-invasive methods of stimulation of functional neurons of the visual cortex.

• Klíčová slova
• age-related macular degeneration, electrophysiological methods, functional magnetic resonance imaging, pigmentary retinopathy, visual neuroprosthesis,
• MeSH
• elektrostimulační terapie * metody   MeSH
• lidé MeSH
• magnetická rezonanční tomografie MeSH
• mozek MeSH
• nervus opticus patologie   MeSH
• zrakové korové centrum * patologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

PURPOSE: The decrease in visual acuity under low luminance conditions is well known. Recent laboratory evidence showed that crowding under low luminance (mesopic) light levels is less robust than under photopic conditions. The present study examines whether such differences in crowding influence clinical measurements of mesopic visual acuity, including test-retest repeatability. METHODS: Twenty adult subjects with normal or corrected to normal visual acuity were recruited for the study. Monocular visual acuity was measured under photopic (228 cd/m2) and mesopic (0.164 cd/m2) luminance conditions using a letter chart, similar in principle to the ETDRS logMAR chart, presented on a computer monitor. Three rows of five letters, each row differing in size by 0.05 logMAR from largest to smallest were displayed at the center of the monitor. The level of crowding was varied by varying the separation between horizontally adjacent letters from 100% optotype size to 50, 20, and 10% optotype size. Inter-row spacing was proportional to optotype size. Observers read the letters on the middle row only. Measurements continued by reducing the size of the letters, until three or more errors on the middle row were made. Each correctly identified letter contributed 0.01 to the recorded logMAR score. All measurements were repeated for each subject on two separate days. RESULTS: Visual acuity (logMAR) was significantly better under photopic than mesopic luminance conditions with a mean difference of 0.48 logMAR. Visual acuity also decreased with decreasing letter separation (i.e. increase in crowding). However, the decrease in visual acuity for the smallest letter separation was less under the mesopic luminance condition, even after accounting for the increased size of threshold acuity letters. Test-retest repeatability for mesopic and photopic conditions was not significantly different. CONCLUSIONS: Crowding under mesopic luminance conditions has less impact on visual acuity than under photopic luminance.

• Klíčová slova
• Crowding, Luminance, Mesopic, Photopic, Visual acuity, logMAR,
• MeSH
• citlivost na kontrast MeSH
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• referenční hodnoty MeSH
• světelná stimulace MeSH
• vidění barevné fyziologie   MeSH
• vidění mezopické fyziologie   MeSH
• zraková ostrost * MeSH
• zrakové testy metody   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Audio-visual integration has been shown to be present in a wide range of different conditions, some of which are processed through the dorsal, and others through the ventral visual pathway. Whereas neuroimaging studies have revealed integration-related activity in the brain, there has been no imaging study of the possible role of segregated visual streams in audio-visual integration. We set out to determine how the different visual pathways participate in this communication. We investigated how audio-visual integration can be supported through the dorsal and ventral visual pathways during the double flash illusion. Low-contrast and chromatic isoluminant stimuli were used to drive preferably the dorsal and ventral pathways, respectively. In order to identify the anatomical substrates of the audio-visual interaction in the two conditions, the psychophysical results were correlated with the white matter integrity as measured by diffusion tensor imaging.The psychophysiological data revealed a robust double flash illusion in both conditions. A correlation between the psychophysical results and local fractional anisotropy was found in the occipito-parietal white matter in the low-contrast condition, while a similar correlation was found in the infero-temporal white matter in the chromatic isoluminant condition. Our results indicate that both of the parallel visual pathways may play a role in the audio-visual interaction.

• Klíčová slova
• DTI, Doubleflash, MRI, Multisensory, TBSS,
• MeSH
• akustická stimulace MeSH
• anizotropie MeSH
• bílá hmota fyziologie   MeSH
• dospělí MeSH
• lidé MeSH
• mapování mozku MeSH
• sluchová percepce fyziologie   MeSH
• světelná stimulace MeSH
• teorie detekce signálu fyziologie   MeSH
• zobrazování difuzních tenzorů MeSH
• zobrazování trojrozměrné MeSH
• zraková percepce fyziologie   MeSH
• zrakové dráhy fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Visual attention modulates the firing rate of neurons in many primate cortical areas. In V4, a cortical area in the ventral visual pathway, spatial attention has also been shown to reduce the tendency of neurons to fire closely separated spikes (burstiness). A recent model proposes that a single mechanism accounts for both the firing rate enhancement and the burstiness reduction in V4, but this has not been empirically tested. It is also unclear if the burstiness reduction by spatial attention is found in other visual areas and for other attentional types. We therefore recorded from single neurons in the medial superior temporal area (MST), a key motion-processing area along the dorsal visual pathway, of two rhesus monkeys while they performed a task engaging both spatial and feature-based attention. We show that in MST, spatial attention is associated with a clear reduction in burstiness that is independent of the concurrent enhancement of firing rate. In contrast, feature-based attention enhances firing rate but is not associated with a significant reduction in burstiness. These results establish burstiness reduction as a widespread effect of spatial attention. They also suggest that in contrast to the recently proposed model, the effects of spatial attention on burstiness and firing rate emerge from different mechanisms.

• Klíčová slova
• attention, burstiness, monkey neurophysiology, visual cortex,
• MeSH
• biologické hodiny fyziologie   MeSH
• Macaca mulatta MeSH
• mozkové vlny fyziologie   MeSH
• nervová síť fyziologie   MeSH
• pozornost fyziologie   MeSH
• vnímání prostoru fyziologie   MeSH
• zraková pole fyziologie   MeSH
• zrakové korové centrum fyziologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH