When horse outlines are filled in with square-wave gratings, they look like zebras when the grating is resolved by the eye. If, in front of the gratings, a progressively increasing number of veiling papers are put unt...
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When horse outlines are filled in with square-wave gratings, they look like zebras when the grating is resolved by the eye. If, in front of the gratings, a progressively increasing number of veiling papers are put until the zebras seem to be horses, it is possible to draw a contrast sensitivity curve as a veiling resistance curve.
visual development was studied in 10 very-low-birth-weight infants (less than 1500 g) with retinopathy of prematurity (ROP) stage 3+ who had been treated with cryocoagulation in both eyes. Binocular visual acuity (acu...
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visual development was studied in 10 very-low-birth-weight infants (less than 1500 g) with retinopathy of prematurity (ROP) stage 3+ who had been treated with cryocoagulation in both eyes. Binocular visual acuity (acuity cards method) and binocular visual fields (kinetic perimetry) were assessed repeatedly in the first year of life. At 12 months corrected age, visual acuity was normal in seven and impaired in three infants, who appeared to be severely myopic. Normal visual fields were found in eight infants at this age. The results indicate that cryotherapy in cases of ROP stage 3+ does not interfere with visual acuity development. The effect on visual field development needs further investigation.
Previous studies have shown that patients diagnosed with schizophrenia (SCZ) have deficits in early visual processing, namely contrast processing. The brain-derived neurotropic factor (BDNF) is an important measure to...
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Previous studies have shown that patients diagnosed with schizophrenia (SCZ) have deficits in early visual processing, namely contrast processing. The brain-derived neurotropic factor (BDNF) is an important measure to investigate neuroplasticity in some visual functions like visual perception. In this study, we investigated the relationship between visual processing and BDNF levels in first-episode SCZ patients. Thirty-nine healthy controls and 43 first-episode SCZ patients were enrolled. Contrast sensitivity measurements were conducted using low, mid- and high spatial frequencies. First-episode SCZ patients had higher contrast sensitivity than healthy controls for all frequencies, except for the middle spatial frequency. Negative correlations were found between BDNF, contrast sensitivity and clinical variables, mostly for middle and high spatial frequencies among females. Our results provide support for (i) the association of SCZ with alterations of magno- and parvocellular pathway functioning and (ii) decreased BDNF levels in first-episode SCZ patients. This study highlights the importance of using biomarkers along with other measures to investigate visual processing in SCZ and other disorders.
visual functions (grating acuity, visual field size, optokinetic nystagmus and eye alignment) were tested as part of a longitudinal study in 96 low-birth-weight infants (birth weight 1500-2500 g) at one year of correc...
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visual functions (grating acuity, visual field size, optokinetic nystagmus and eye alignment) were tested as part of a longitudinal study in 96 low-birth-weight infants (birth weight 1500-2500 g) at one year of corrected age. Except for optokinetic nystagmus, deficit rates of all visual functions were low, and the obtained values comparable with normal age values in full-term infants. Effects of gestational duration, birth weight and intrauterine growth retardation on visual functions could not be demonstrated. Some perinatal risk factors (mechanical ventilation, oxygen treatment for more than one day, the presence of maternal hypertensive disorders) and a less-optimal neurodevelopmental status at one year had a negligible effect on visual field size. The observed deficits are not likely to cause disability. Low-birth-weight infants appeared not to be at risk for developing visual deficits at one year of corrected age.
This article, based on a report prepared for the International Council of Ophthalmology (ICO) and the International Society for Low Vision Research and Rehabilitation (ISLRR), explores the assessment of various aspect...
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This article, based on a report prepared for the International Council of Ophthalmology (ICO) and the International Society for Low Vision Research and Rehabilitation (ISLRR), explores the assessment of various aspects of visual functioning as needed to document the outcomes of vision rehabilitation. Documenting patient abilities and functional vision (how the person functions) is distinct from the measurement of visual functions (how the eye functions) and also from the assessment of quality of life. All three areas are important, but their assessment should not be mixed. Observation of task performance offers the most objective measure of functional vision, but it is time-consuming and not feasible for many tasks. Where possible, timing and error rates provide an easy score. Patient response questionnaires provide an alternative. They may save time and can cover a wider area, but the responses are subjective and proper scoring presents problems. Simple Likert scoring still predominates but Rasch analysis, needed to provide better result scales, is gaining ground. Selection of questions is another problem. If the range of difficulties does not match the range of patient abilities, and if the difficulties are not distributed evenly, the results are not optimal. This may be an argument to use different outcome questions for different conditions. Generic questionnaires are appropriate for the assessment of generic quality of life, but not for specific rehabilitation outcomes. Different questionnaires are also needed for screening, intake and outcomes. Intake questions must be relevant to actual needs to allow prioritization of rehabilitation goals;the activity inventory presents a prototype. Outcome questions should be targeted at predefined rehabilitation goals. The Appendix cites some promising examples. The Low Vision Intervention Trial (LOVIT) is an example of a properly designed randomized control study, and has demonstrated the remarkable effectiveness of vision
The Nobel Prizes for Physiology or Medicine have included a relatively large number of awards for work in the neurosciences, or for work construed to have made a contribution to neuroscience. These are recognized in t...
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The Nobel Prizes for Physiology or Medicine have included a relatively large number of awards for work in the neurosciences, or for work construed to have made a contribution to neuroscience. These are recognized in this article by brief explanations of the particular contribution that warranted this magnificent (and munificent) award. The first prizes in neuroscience were awarded five years after the initiation of the Nobel Foundation's program. Up to 2005, 28 prizes have been awarded for achievements in neuroscience to 52 individuals.
Background: Age-related vision changes significantly contribute to fatal crashes at night among older drivers. However, the effects of lighting conditions on age-related vision changes and associated driving performan...
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Background: Age-related vision changes significantly contribute to fatal crashes at night among older drivers. However, the effects of lighting conditions on age-related vision changes and associated driving performance remain unclear. Objective: This pilot study examined the associations between visual function and driving performance assessed by a high-fidelity driving simulator among drivers 60 and older across 3 lighting conditions: daytime (photopic), nighttime (mesopic), and nighttime with glare. Methods:Active drivers aged 60 years or older participated in visual function assessments and simulated driving on a high-fidelity driving simulator. visual acuity (VA), contrast sensitivity function (CSF), and visual field map (VFM) were measured using quantitative VA, quantitative CSF, and quantitative VFM procedures under photopic and mesopic conditions. VA and CSF were also obtained in the presence of glare in the mesopic condition. Two summary metrics, the area under the log CSF (AULCSF) and volume under the surface of VFM (VUSVFM), quantified CSF and VFM. Driving performance measures (average speed, SD of speed [SDspeed], SD of lane position (SDLP), and reaction time) were assessed under daytime, nighttime, and nighttime with glare conditions. Pearson correlations determined the associations between visual function and driving performance across the 3 lighting conditions. Results: Of the 20 drivers included, the average age was 70.3 years;55% were male. Poor photopic VA was significantly correlated with greater SDspeed (r=0.26;P<.001) and greater SDLP (r=0.31;P<.001). Poor photopic AULCSF was correlated with greater SDLP (r=-0.22;P=.01). Poor mesopic VUSFVM was significantly correlated with slower average speed (r=-0.24;P=.007), larger SDspeed (r=-0.19;P=.04), greater SDLP (r=-0.22;P=.007), and longer reaction times (r=-0.22;P=.04) while driving at night. For functional vision in the mesopic condition with glare, poor VA was significantly correlated with longer
Human vision is roughly composed of two distinct but integrated functional pathways: vision-for-recognition and vision-for-action. Likewise, display form factors can be categorized as passive viewing (e.g., office wor...
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Human vision is roughly composed of two distinct but integrated functional pathways: vision-for-recognition and vision-for-action. Likewise, display form factors can be categorized as passive viewing (e.g., office work on a computer or movie viewing on a TV) and active interaction (e.g., VR and AR in gaming). Theoretical and empirical findings suggest the encoding of visual inputs can affect by task demands. Here we evaluated two corresponding methods of measuring image quality for visual consumption. The method of measuring vision-for-recognition involves direct visual comparison to discern any degraded visual quality. visual attention is critical in such paradigm. Conversely, a novel method of assessing visual quality for vision-for-action is to assess how visuomotor responses are facilitated or altered independent of conscious detection. We reported empirical data obtained with a gaze-contingent flicker paradigm to measure the rate of detecting visual degradation and altered eye movements. These findings show that consciously invisible changes in visual image can alter viewing eye movements and conscious decision; conversely, the possibility of detecting visual degradation can be overestimated because of artificially manipulated attention. These findings call for a new approach to measure visual quality for different form factors and task requirements.
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