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  • cortical
  • Effects of aging on cortical thickness (CT) have been observed in many brain regions, including areas involved in basic perceptual functions such as processing visual inputs. (frontiersin.org)
  • An important property of early visual cortices is their topographic organization-the cortical structure of early visual areas forms a topographic map of retinal inputs. (frontiersin.org)
  • Primary visual cortex (V1) is considered to be the most basic cortical area in the visual processing hierarchy, and is topographically organized from posterior (central visual representation) to anterior (peripheral visual representation) along the calcarine sulcus. (frontiersin.org)
  • Some studies have reported strong age-dependent cortical thinning in portions of V1 that likely correspond to peripheral visual representations, while there is less evidence of substantial cortical thinning in central V1. (frontiersin.org)
  • retinal
  • but it's also helpful for retinal conditions and instances when visual field function needs to be measured. (slideshare.net)
  • The investigators measured the visual field sensitivity of patients with diabetes both with and without mild to moderate diabetic retinopathy, as defined by retinal vascular lesions. (diabetesjournals.org)
  • Because the early visual field deficits in the current study were not correlated with typical risk factors such as blood glucose control or retinal appearance, the clinical assessment of vision beyond the standard letter chart should be investigated for detection of patients at risk for diabetic retinopathy. (diabetesjournals.org)
  • In an analogy to Meridian (geography), in which meridians are lines of longitude, the North pole might correspond to the fovea, Greenwich would correspond to a retinal location about 39 degrees to the left of the fovea (because the retinal image is inverted, this corresponds to a location in the visual field to the observer's right), and the South pole would correspond to the centre of the pupil. (wikipedia.org)
  • contralateral visual
  • iii ) In primary visual cortex V1, the contralateral visual hemifield is represented in a smooth, topographically organized map which, in primates, is subdivided into columnar systems representing the 2 eyes and various feature domains such as orientation, spatial frequency, and color. (pnas.org)
  • IV) In primates visual areas V2 and V3 contain maps of quarterfield representations of upper and lower contralateral visual fields that are mirrored along the representations of the vertical and horizontal meridians between adjacent areas ( 3 , 10 , 11 ). (pnas.org)
  • In this way, if a cerebral hemisphere has functional advantages with some aspect of a particular task, an experimenter might observe improvements in task performance when the visual information is presented on the contralateral visual field. (wikipedia.org)
  • symptomatic
  • These three cases have the common feature of symptomatic constriction of the visual field two to three years after starting vigabatrin treatment. (bmj.com)
  • quadrantanopia
  • Quadrantanopia, quadrantanopsia, or quadrant anopia refers to an anopia affecting a quarter of the field of vision. (wikipedia.org)
  • Binasal (either inferior or superior) quadrantanopia affects either the upper or lower inner visual quadrants closer to the nasal cavity in both eyes. (wikipedia.org)
  • Bitemporal (either inferior or superior) quadrantanopia affects either the upper or lower outer visual quadrants in both eyes. (wikipedia.org)
  • An interesting aspect of quadrantanopia is that there exists a distinct and sharp border between the intact and damaged visual fields, due to an anatomical separation of the quadrants of the visual field. (wikipedia.org)
  • Individuals with quadrantanopia often modify their behavior to compensate for the disorder, such as tilting of the head to bring the affected visual field into view. (wikipedia.org)
  • abnormalities
  • Although numerous studies have been published, few studies have described the natural history of the visual function abnormalities associated with this disease. (diabetesjournals.org)
  • 1 ) provide one of the first natural history descriptions of early visual function abnormalities in patients with early-stage diabetic retinopathy. (diabetesjournals.org)
  • The manufacturers of vigabatrin had received 28 reports of visual field abnormalities worldwide by January 1997 in an estimated 140 000 patients treated (Hoechst Marion Roussel, personal communication). (bmj.com)
  • retina
  • Evidence has now accumulated to convince all but the most sceptical that the antiepileptic drug vigabatrin, an irreversible inhibitor of GABA transaminase, has a strong tendency to produce visual field constriction by a toxic effect on the retina, although the precise mechanism by which it does so has yet to be identified. (bmj.com)
  • Visual field refers to the patterning of the reception of the entire retina . (healthtap.com)
  • Another way of thinking of the maximum visual field is to think of all of the retina that can be reached by light from the external environment. (wikipedia.org)
  • The visual field in this case is all of the external environment that can project light onto the retina. (wikipedia.org)
  • occur
  • Although patient numbers remain small (only 11 of the tiagabine treated patients were able to produce reliable visual fields), these results, taken with those of Nousiainen et al , 4 indicate that visual field constriction is at worst a much rarer side effect of tiagabine than vigabatrin, and at best may not occur with the drug. (bmj.com)