Foveal

About: Foveal is a research topic. Over the lifetime, 2652 publications have been published within this topic receiving 94120 citations.

Gaze-contingent video resolution degradation

Abstract: Experimental results are presented evaluating two wavelet- based gaze-contingent video resolution degradation methods under three foveal Region of Interest (ROI) placement strategies. ROI placement is described by the introduction of a novel visualization of viewers' scanpaths, termed Volumes of Interest (VOIs). VOIs represent foveal loci of gaze in 3D space-time. Three ROI placement strategies, ideal, preattentive, and aggregate, are used to determine the location of an unprocessed, dynamic spatial resolution region corresponding to the projected dimension of the fovea. Results indicate imperceptible degradation effects of both ideal and preattentive strategies under a visual tracking paradigm.

Task-driven visual exploration at the foveal scale.

Abstract: Humans use saccades to inspect objects of interest with the foveola, the small region of the retina with highest acuity. This process of visual exploration is normally studied over large scenes. However, in everyday tasks, the stimulus within the foveola is complex, and the need for visual exploration may extend to this smaller scale. We have previously shown that fixational eye movements, in particular microsaccades, play an important role in fine spatial vision. Here, we investigate whether task-driven visual exploration occurs during the fixation pauses in between large saccades. Observers judged the expression of faces covering approximately 1°, as if viewed from a distance of many meters. We use a custom system for accurately localizing the line of sight and continually track gaze position at high resolution. Our findings reveal that active spatial exploration, a process driven by the goals of the task, takes place at the foveal scale. The scanning strategies used at this scale resemble those used when examining larger scenes, with idiosyncrasies maintained across spatial scales. These findings suggest that the visual system possesses not only a coarser priority map of the extrafoveal space to guide saccades, but also a finer-grained priority map that is used to guide microsaccades once the region of interest is foveated.

Parameters of fixation disparity.

Abstract: This paper reviews the definition, causation, and significance of fixation disparity and suggests that the magnitude and character of fixation disparity depend on several major parameters: individual differences in the efficiency of motor and sensory processes of binocularity; natural or prism-induced demands on motor fusion; the presence or absence of foveal or parafoveal fusion clues; and the presence or absence of vergence adaptation. The clinical and research usefulness of fixation disparity as an indicator of binocular stress is emphasized.

Scanning laser ophthalmoscope correlations with biomicroscopic findings and foveal function after macular hole closure.

Abstract: Objective To investigate the relation between foveal findings and visual function in eyes with a resolved idiopathic macular hole after vitreous surgery. Methods We divided 28 eyes with postoperative idiopathic macular hole resolution into 3 groups based on postoperative biomicroscopic foveal findings of complete closure, partial closure, or atrophic closure. To evaluate foveal retinal function, scanning laser ophthalmoscope (SLO) microperimetry was performed preoperatively and 6 months postoperatively. Results Postoperatively in 18 eyes (64%), the foveal images became normal or almost normal and were classified as having complete closure, 6 eyes (21%) were classified as having partial closure, and 4 eyes (14%) as having atrophic closure. The corresponding visual acuity levels 6 months postoperatively were, respectively, 0.10, 0.35, and 0.64 ( P Conclusions After macular hole closure, SLO findings correlate both with biomicroscopic findings and foveal function. Better anatomical foveal recovery in eyes after macular hole closure results in better improvement of vision than in eyes in which the foveal anatomical findings are not as good.

Müller cell alignment in bird fovea: possible role in vision.

Abstract: Birds which possess high visual acuity, such as eagles and falcons, are known to have retinas with a deep conically curved central foveal pit. There have been different attempts to explain the importance of this particular shape of the fovea in visual resolution. Recently, the function of Muller cells as "light fibers" was discovered, showing how the endfeet of Muller cells trap the light and then transfer it to a single cone photoreceptor. Here we describe how the endfeet of Muller cells line the walls of the foveal pit in the Pied Flycatcher, and how the Muller cell body extends its processes towards individual cones, forming machinery that could allow for light transfer from the pit wall to the photoreceptor layer alongside the pit. We describe how this construction may send an image from the fovea to the cones, and also, how the angular positioning of Muller cells, being optical extensions of the cones, has the advantage of being much denser than on a flat or slightly curved fovea. We, therefore, suggest that this type of optic fiber alignment can be used as a novel type of "amplifying array" that simply increases the amount of megapixels at the photoreceptor cell layer.