Experimental implantation and long-term testing of an intraocular vision aid in rabbits.
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Animals↗
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Results for “Computer vision”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
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Rhinogenous optic neuritis with drastic diurnal variation of visual function.
We report a case of rhinogenous optic neuritis in a 50-year-old man demonstrating drastic diurnal variation in visual function. His left vision was 20/15 in the morning, which gradually decreased to counting fingers at night. Pupillary reaction and visual field showed the same fluctuation as vision. Complete remission of visual symptoms was achieved after endonasal ethmoid sinusotomy.
Circadian Rhythm↗
[Vision test program for ophthalmologists on Apple II, IIe and IIc computers].
A microcomputer program for the Apple II family of computers on a monochrome and a color screen is described. The program draws most of the tests used by ophthalmologists, and is offered as an alternative to a projector system. One advantage of the electronic generation of drawings is that true random orientation of Pflueger's E is possible. Tests are included for visual acuity (Pflueger's E, Landolt rings, numbers and children's drawings). Colored tests include a duochrome test, simple color vision tests, a fixation help with a musical background, a cobalt blue test and a Worth figure. In the astigmatic dial a mobile pointer helps to determine the axis. New tests can be programmed by the user and exchanged on disks among collageues.
Color Perception Tests↗
[PC software for evaluating the Farnsworth-Munsell 100-Hue test].
This computer program is designed for faster elaboration of the Farnsworth-Munsell 100-Hue test. It is thus made user friendly, in that faultless input of data can be achieved, even by an untrained person. Evaluation is facilitated by the opportunity of representing two results at the same time. Examples of typical colour vision deficiencies are stored in a file and can then also be called up. Storing the results in a special data file helps to avoid the time consuming printing process. However, a hardcopy is supported by storing the last grafic in a standard PostScript-file, thus giving easy access to any printer. This program is applicable for IBM- or compatible PCs. Extensive use is possible by means of a software interface with the wide spread database-system DBASE.
Color Perception Tests↗
Computer and World Wide Web accessibility by visually disabled patients: problems and solutions.
Rapid advances in information technology have dramatically transformed the world during the past several decades. Access to computers and the World Wide Web is increasingly required for education and employment, as well as for many activities of daily living. Although these changes have improved society in many respects, they present an obstacle for visually disabled patients who may have significant difficulty processing the visual cues presented by modern graphical user interfaces. This article reviews the specific barriers to computer and Web access faced by visually disabled patients, describes clinical evaluation methods, summarizes traditional low vision methods as well as newer assistive computer technologies for universal accessibility, and discusses emerging technologies and future directions in this area.
Access to Information↗
[The Freiburg Vision Test. Automated determination of visual acuity].
The Freiburg Visual Acuity Test is an automatic computerized procedure for self-administered measurement of visual acuity. Landolt-Cs are presented on a monitor in one of eight orientations. The subject presses one of eight buttons, which are spatially arranged according to the eight possible positions of the Landolt-C's gap. To estimate the acuity threshold, a best-PEST procedure is employed, assuming a psychometric function with a constant slope on a logarithmic acuity scale. The discreetness artifacts in computer monitors limit the presentation of small stimuli. By anti-aliasing (smoothing of contours by gray-shading), the spatial resolution was improved by a factor of four, such that the shape of Landolt-Cs with oblique gaps is adequate and visual acuities from 0.06 up to 3.6 can be tested at a distance of 5 m.
Artifacts↗
Advanced diagnostic procedures for evaluating the visual status of the child.
Single cell studies of cats and monkeys, recent behavioral testing methods, and improved sophisticated electrodiagnostic procedures have resulted in a new awareness of and concern for the development of the visual system. This paper will review select relevant research and highlight some of the new diagnostic vision tests presently available for the clinical assessment of infants and young children.
Amblyopia↗
High technology for low vision.
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Humans↗
Tunnel vision to tunnel mind.
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Computer Graphics↗
Spatial attention and crossmodal interactions between vision and touch.
In the present paper, we review several functional imaging studies investigating crossmodal interactions between vision and touch relating to spatial attention. We asked how the spatial unity of a multimodal event in the external world might be represented in the brain, where signals from different modalities are initially processed in distinct brain regions. The results highlight several links between visual and tactile spatial representations. First, we found that activity in the anterior part of the intraparietal sulcus was influenced by stimulus position independently of the modality of the stimulation. This is consistent with crossmodal interactions via sensory convergence from early modality-specific spatial maps to higher-order multimodal regions. Second, we found that stimulation in, or attention to, one modality could affect activity in areas dedicated to a different modality, in a spatially-specific manner. These spatial crossmodal effects in unimodal regions demonstrate congruous activity in anatomically distant brain areas that represent similar external locations, implicating a distributed network of spatial representations in crossmodal integration. Finally, the results suggest that the temporo-parietal junction may be involved in aspects of controlling spatial attention, for both vision and touch. A multimodal attentional system may influence activity in distinct brain areas representing common regions of space for different modalities, thus suggesting a link between spatial attention and crossmodal integration.
Attention↗
Experimental implantation and long-term testing of an intraocular vision aid in rabbits.
OBJECTIVE: To develop an intraocular vision aid to provide artificial vision in severely traumatized eyes, where neuroretinal function could be preserved but irreversible anterior segment opacification resulted in blindness. METHODS: The basis of an intraocular vision aid is in principle a telemetric circuit to bridge the opaque cornea and to allow for artificial light stimulation of the retina. The visual prosthesis comprises an external high-dynamic range complementary metal oxide semiconductor camera and digital signal processing unit and an intraocular miniaturized light-emitting diode array to project the image onto the retina. For in vivo testing of long-term function and biocompatibility, silicone-encapsulated active photodiodes were implanted in 13 pigmented rabbits and were followed up for up to 21 months. RESULTS: Lens extraction and stable fixation of the device in the ciliary sulcus were successful in all cases. For up to 21 months inductive energy transmission and wireless stimulation of the implants could be maintained. Electrophysiologic data and histology demonstrated a good tissue biocompatibility in the long-term follow-up. CONCLUSION: The results demonstrate the general feasibility and biocompatibility to implant and fixate an intraocular light-emitting diode prosthesis. Inductive energy transmission to the intraocular device and wireless light stimulation are assured in the long term but depend on meticulous water-impermeable encapsulation of the delicate microelectronic components. Clinical Relevance An intraocular vision aid compound system with a high-resolution light-emitting diode matrix might be a future treatment option to restore vision in blind eyes with severe anterior segment disorders.
Animals↗
Insect vision: controlling actions through optic flow.
Insects depend upon optic flow to supply much of their information about the three-dimensional structure of the world. Many insects use translational flow to measure the distance of objects from themselves. A recent study has provided new insights into the way Drosophila use optic flow to pick out a close target to approach.
Animals↗
Resolving border disputes in midlevel vision.
Two papers in this issue of Neuron specify the coding of border ownership, the basis of figure-ground segmentation, in early extrastriate visual cortex (area V2). Recording from a population of neurons, Qiu and von der Heydt show that border ownership assignments based on 2D images show the same bias when tested with stereopsis. Zhaoping shows that a neural model of V2 can make appropriate border assignments based on 2D images.
Form Perception↗
A new approach to vision screening in schools.
PURPOSE: To determine the prevalence of visual "defects" among a sample of young schoolchildren and evaluate a new system for vision screening in schools. METHODS: A new system for vision screening in schools has been developed. The system is based on a computer program which may be run on a low specification personal computer. Information about the child's symptoms, history and family history is acquired by means of a parental questionnaire and entered into the program prior to the vision screening. Distance visual acuity and stereopsis are measured directly on the computer screen and colour vision is assessed using a reduced Ishihara test. The program carries out an "expert" analysis of the questionnaire data and the vision test results and determines the most likely diagnosis. Reports for parents, teachers, optometrists, doctors can be generated automatically and statistics relating to the overall screening program are available. An evaluation of a prototype version of the system was carried out on 245 schoolchildren aged between 5 and 8 years. RESULTS: Overall, 48 children failed the screening (excluding colour vision deficiencies), 32 of whom were unaware of any problem with their eyes. Comparison of the result of the vision screening with the outcome of a full eye examination gave a sensitivity of 93.8% and a specificity of 96.1%. CONCLUSION: A significant number of young school children have unsuspected remediable visual defects. The computer-based vision screener provides an efficient, sensitive and specific method for screening in schools.
Child↗
Real time image processing with an analog vision chip system.
A linear analog network model is proposed to characterize the function of the outer retinal circuit in terms of the standard regularization theory. Inspired by the function and the architecture of the model, a vision chip has been designed using analog CMOS Very Large Scale Integrated circuit technology. In the chip, sample/hold amplifier circuits are incorporated to compensate for statistic transistor mismatches. Accordingly, extremely low noise outputs were obtained from the chip. Using the chip and a zero-crossing detector, edges of given images were effectively extracted in indoor illumination.
Adaptation, Ocular↗
Influence of differences of visual acuity in various visual field conditions on spectral characteristics of the center of pressure sway.
This study examined the influence of visual acuity and visual field on the spectral characteristics of the center of pressure during standing. 17 men and 20 women participated in High and Low visual acuity groups. Both groups underwent center of pressure measurements under three visual field conditions: No vision: subjects were given no visual information, Central vision: they were given only central visual field information, and Full vision: they were given full visual information. To assess the spectral characteristics of center of pressure, mean power frequency and frequency of maximal power were calculated from medial-lateral and anterior-posterior center of pressure directions. The Friedman test and Scheffé pairwise comparison tests showed that frequency of maximal power was higher in the No vision than in the Central and Full vision conditions in the High visual acuity group. In conclusion, people with high visual acuity are more susceptible to visual field conditions than those with low visual acuity. It is suggested that postural control characteristics differ with visual acuity or resolution in the central visual field.
Adult↗
Arcuate foramen and its clinical significance.
OBJECTIVE: The present study determines the degree of ossification of the posterior atlanto-occipital membrane in dry bone, plane lateral cervical spine radiographs and computer tomography (CT). The average length, width and the area of the arcuate foramen were measured on dry bone and on cervical CT. Further, age, gender and complaints of the patients of shoulder and arm pain, neck pain, headache, vertigo, and lacrimation in relation to the presence of bony complete or incomplete arcuate foramen were evaluated. METHODS: From February 2004 to January 2005 60 dry atlases were obtained from the Anatomy Department, University of Marmara, Istanbul, Turkey and 416 lateral cervical spine radiographs were obtained from the Radiology department for neurological and orthopedic evaluations. Each complete arcuate foramen was calculated with the aid of Clemex Vision PE demo version computer program. RESULTS: Among the 60 dry atlases examined 7 (11.7%) had complete and 2 (3.3 %) had incomplete bony bridge formation. Of the 416 plane lateral cervical spine radiographs examined, 30 (7.2%) had complete and 26 (6.25%) had incomplete bony bridge formation. Of the 30 complete arcuate foramen 24 (80%) were females and 6 (20%) were males. The frequency of having a complete arcuate foramen in females was 8.45%, and in males it was 4.55%. Further, of the 26 incomplete arcuate foramen 20 (76.9%) were females and 6 (23.1%) were males. The frequency of having an incomplete arcuate foramen in females was 7%, and in males was 4.55%. The statistical evaluations showed that patients with complete arcuate foramen had significant complaints of shoulder-arm pain (p=0.0072), neck pain (p=0.0072) and vertigo (p=0.0598) compared to patients with incomplete arcuate foramen. The patients with complete arcuate foramen had a headache ratio of 12:30 and this ratio was 2:26 in patients with incomplete arcuate foramen and the difference between complete and incomplete arcuate foramen was statistically significant (p=0.0062). Further, no statistically significant relation was observed between both complete and incomplete arcuate foramen and lacrimation. No relationship between age and the presence of complete and incomplete arcuate foramen was observed. CONCLUSION: Presence of an arcuate foramen is always underestimated. Its presence should always be keep in mind in patients complaining of shoulder-arm and neck pain, headache and vertigo are examined.
Adult↗
[Impairment of safety in navigation caused by alcohol: impact on visual function].
BACKGROUND: So far in Germany, no legally binding standards for blood alcohol concentration exist that prove an impairment of navigability. The aim of our interdisciplinary project was to obtain data in order to identify critical blood alcohol limits. In this context the visual system seems to be of decisive importance. MATERIALS AND METHODS: 21 professional skippers underwent realistic navigational demands soberly and alcoholized in a sea traffic simulator. The following parameters were considered: visual acuity, stereopsis, color vision, and accommodation. RESULTS: Under the influence of alcohol (average blood alcohol concentration: 1.08 per thousand ) each skipper considered himself to be completely capable of navigating. While simulations were running, all of the skippers made nautical mistakes or underestimated dangerous situations. Severe impairment in visual acuity or binocular function were not observed. Accommodation decreased by an average of 18% ( p=0.0001). In the test of color vision skippers made more mistakes ( p=0.017) and the time needed for this test was prolonged ( p=0.004). CONCLUSIONS: Changes in visual function as well as vegetative and psychological reactions could be the cause of mistakes and alcohol should therefore be regarded as a severe risk factor for security in sea navigation.
Accidents↗