Search results
Results from the WOW.Com Content Network
Classical image of the shape and size of the visual field [28]. The outer boundaries of peripheral vision correspond to the boundaries of the visual field as a whole. For a single eye, the extent of the visual field can be (roughly) defined in terms of four angles, each measured from the fixation point, i.e., the point at which one's gaze is directed.
An examiner presents a test light of variable size and intensity. The light may move towards the center from the perimeter (kinetic perimetry), or it may remain in one location (static perimetry). The Goldmann method is able to test the entire range of peripheral vision and has been used for years to follow vision changes in glaucoma patients. [3]
The visual system is organized hierarchically, with anatomical areas that have specialized functions in visual processing. Low-level visual processing is concerned with determining different types of contrast among images projected onto the retina whereas high-level visual processing refers to the cognitive processes that integrate information from a variety of sources into the visual ...
The results of the analyser identify the type of vision defect. Therefore, it provides information regarding the location of any disease processes or lesion(s) throughout the visual pathway. This guides and contributes to the diagnosis of the condition affecting the patient's vision.
An object is presented from far peripheral and slowly moves into the center of the vision, while the child maintains fixation on a central target. [13] The point at which the peripheral object captures the child’s attention and prompts a shift in gaze or fixation marks the boundary of their visual field. [13]
Summary: Cervico-ocular reflex, also known by its acronym COR, involves the achievement of stabilization of a visual target, [28] and image on the retina, through adjustments of gaze impacted by neck and, or head movements or rotations. The process works in conjunction with the vestibulo-ocular reflex (VOR). [29]
The reduction of the number of neurons per visual field area from foveal to peripheral representations is achieved in several steps along the visual pathway, starting already in the retina. [1] For quantitative purposes, the cortical magnification factor is normally expressed in millimeters of cortical surface per degree of visual angle.
In reality it is smaller than this, and irregular, because when the observer is looking straight ahead, his or her nose blocks vision of some possible parts of the surface. In perimetric testing, a section of the imaginary sphere is realized as a hemisphere in the centre of which is a fixation point. Test stimuli can be displayed on the hemisphere.