|
| ||
|
|
||
Binocular Vision (binocular + vision)
Selected AbstractsBinocular interaction and performance of visual tasksOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 2 2004Maria S. Justo Abstract Binocular vision implies the fusion of the right and left retinal images to perceive a single image. For this, interocular interaction is required. We measured the reaction times to carry out a visual fixation task in order to determine whether binocular interaction influences performance. Several combinations of test and distraction stimuli were monocularly and binocularly presented to one monkey and three human subjects. The overall median reaction times were 340 ms for the animal and 308, 342 and 381 for human subjects 1, 2 and 3 respectively. Reaction time was shorter when the test stimulus was presented binocularly. Moreover, we observed that the presence of a distraction stimulus increased the reaction time and that a correlated distraction stimulus had a greater influence on this increase than an uncorrelated distraction stimulus. These findings indicate that with binocular vision a more rapid performance of a visual task occurs. [source] Impairment of binocular vision in the adult cat induces plastic changes in the callosal cortical mapEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2001Laurent Watroba Abstract In the primary visual cortex of normally reared adult cat, neurons activated through the corpus callosum are almost entirely located at the 17/18 border. They display small receptive fields distributed along the central vertical meridian of the visual field and are orientation selective. Here we demonstrate that a few weeks of monocular deprivation or unilateral convergent strabismus produced in adulthood does not modify the cortical distribution of these neurons, but leads to an increase of their receptive field size mainly toward the ipsilateral hemifield and to a loss of their orientation selectivity. We conclude that manipulation of binocular vision in the adult modifies neither the location of the primary callosal cortical map nor its retinotopy. In contrast, it induces functional plastic changes in this map which lead to a significant widening of the area of visual space signalled through the corpus callosum. These plastic changes are interpreted as the result of the strengthening of normally hidden subthreshold synaptic inputs. [source] The absence of lateral congruency between sighting dominance and the eye with better visual acuityOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2007Jonathan S. Pointer Abstract The notion that in subjects with normal binocular vision (i.e. non-strabismic cases) the eye showing sighting dominance will also most likely be that individual's better-sighted eye has proved to be persistent. A review and analysis of the literature has now demonstrated, across several population groups, the fallacy of this belief. In fact, the occurrence of lateral congruency between sighting dominance and the eye with better visual acuity is at a statistical level no greater than chance would predict. Some clinical implications of this outcome are considered. [source] Binocular interaction and performance of visual tasksOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 2 2004Maria S. Justo Abstract Binocular vision implies the fusion of the right and left retinal images to perceive a single image. For this, interocular interaction is required. We measured the reaction times to carry out a visual fixation task in order to determine whether binocular interaction influences performance. Several combinations of test and distraction stimuli were monocularly and binocularly presented to one monkey and three human subjects. The overall median reaction times were 340 ms for the animal and 308, 342 and 381 for human subjects 1, 2 and 3 respectively. Reaction time was shorter when the test stimulus was presented binocularly. Moreover, we observed that the presence of a distraction stimulus increased the reaction time and that a correlated distraction stimulus had a greater influence on this increase than an uncorrelated distraction stimulus. These findings indicate that with binocular vision a more rapid performance of a visual task occurs. [source] Prioritization of cataract surgery: Visual analogue scale versus scoring systemANZ JOURNAL OF SURGERY, Issue 7 2005Victoria W. Y. Wong Background: The purpose of the present paper was to evaluate the variability of using a visual analogue scale (VAS) and to assess the feasibility of a priority-setting scoring system for prioritizing elective cataract surgery. Methods: Consecutive cases listed for cataract surgery were prospectively recruited. Ophthalmologists listed patients to undergo early or normal surgery and were asked to rate the urgency of surgery using a VAS. Patients were then reassessed and a cataract surgery prioritization (CSP) score was calculated based on the New Zealand priority criteria for cataract surgery. Correlation coefficients between VAS and CSP scores were calculated to determine the variability among ophthalmologists in using the VAS in prioritizing surgery. Further analyses were performed to assess the potential impact of implementing the CSP system. Results: A total of 326 patients were recruited. There was a positive correlation between VAS and CSP scores (Spearman ,= 0.407, P < 0.001). A high degree of variation among ophthalmologists in the use of VAS was found. Patients with poor binocular vision were not listed as early, whereas patients with poor vision in the eye listed for cataract surgery but good vision in the fellow eye were more likely to be prioritized to have early operation. These findings suggest that patients with severe impairment in binocular visual function were not adequately accounted for during cataract surgery listing. Conclusions: The use of a VAS for prioritizing cataract surgery may be suboptimal due to high subjectivity. Adoption of an objective criteria-validated priority-setting scoring system may allow better stratification of patients to ensure better service provision. [source] 2461: Increasing complexity of ocular genetic diseases : the case of BEST diseaseACTA OPHTHALMOLOGICA, Issue 2010M ABITBOL Purpose Monogenic diseases until recently appeared simple from a molecular genetics point of view but correlations between genotypes and phenotypes still remain difficult to establish in many diseases and for many genes. For autosomal dominant diseases such as Best Vitelliform Macular Dystrophy, supposed to be a juvenile disease, it appears that mutations of BEST1 gene can cause multiple phenotypes including early onset and late onset phenotypes as well as unexpected phenotypes such as RP. We report several novel mutations and their associated phenotypes and describe phenotypes linked to previously reoported mutations for which the phenotype had not been describe at all previously. The role of SOX9, MITF and OTX2 in the incomplete penetrance and the variable expressivity of BVMDs is duscussed as well the potential roles of SNPs occuring in coding exons Methods We used genomic PCR with appropriate primers flanking all the exons of the BEST1 gene in order to amplify them. This Genomic PCR was followed by automated sequencing and careful analysis of the sequences obtained. Results We report the case of an unusual family where the Mother II2 of the proband III1, his maternal aunt II3, his brother III3 and his first cousin IIIIV, the son of his maternal aunt, carry a missense mutatation causing apparently only electrophysiological abnormalities. The Father II1 of the proband III1 turned out to carry a stop codon instead of the fifth normal BEST1 codon. The father did not display any electrophysiological nor any clinical abnormality and has a perfect monocular and binocular vision. In contrast the proband III1 carries both mutations with a severe phenotype. Conclusion This report exemplifies the necessity to study all family members in the case of BVMDs. [source] Postural stability in primary open angle glaucomaCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 3 2005Noor Shabana MB BS Abstract Background:, This study evaluated the visual contribution to postural steadiness in primary open angle glaucoma (POAG), in correlation with the mean deviation (MD) measured through conventional perimetry, and with the Advanced Glaucoma Intervention Study (AGIS) score, which quantifies the extent of losses in the visual field. Methods:, In 35 POAG patients and 21 age-matched normal subjects, the sway of the centre of pressure of the feet, on a firm or foam support, was recorded. The subjects stood on a force-plate with eyes closed, or with one or two eyes open. Results:, For all subjects, the sway velocity was lower with vision than without vision, indicating the existence of a visual contribution to posture at all stages of glaucoma. This contribution was significantly lower for POAG patients than for normals in monocular and binocular vision, and decreased with the MD, or as the AGIS score increased. Among the maximum, minimum and average values of the two monocular MD, the MD of the worse eye presented the most significant negative correlation with the visual contribution to posture. The somatosensory contribution to postural steadiness was larger in POAG patients, as compared to normals, in monocular or binocular vision. Conclusion:, Primary open angle glaucoma induces a deficit in the visual contribution to postural steadiness, which should be taken into account for the prevention of falls. [source] Sensory ocular dominance based on resolution acuity, contrast sensitivity and alignment sensitivityCLINICAL AND EXPERIMENTAL OPTOMETRY, Issue 1 2009Catherine Suttle PhD MCOptom Background:, Ocular dominance is the superiority or preference of one eye over the other in terms of sighting, sensory function (for example, visual acuity) or persistence in binocular rivalry. There is poor agreement between sighting and sensory dominance and findings are equivocal on the possible neural basis of ocular dominance and its significance. Thus, there are questions on the meaning and importance of ocular dominance. Despite the lack of clarity in this area, ocular dominance is used clinically, for example, as the basis for decisions on monovision in contact lens wear and on treatment of anomalies of binocular vision. Methods:, Sighting dominance and three types of sensory dominance (based on resolution acuity, contrast sensitivity and alignment sensitivity) were compared within individuals, with the main aim of determining whether sensory dominance is consistent across spatial visual functions. Results:, Our findings indicate that each type of sensory dominance is insignificant in most individuals and in agreement with previous work that sensory and sighting dominance do not generally agree. Conclusion:, These results demonstrate not only that different types of ocular dominance are not in agreement but also that in the normal visual system sensory dominance as measured here is insignificant in most individuals with normal vision. [source] | ||||||||||