Topic
Foveal
About: Foveal is a research topic. Over the lifetime, 2652 publications have been published within this topic receiving 94120 citations.
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TL;DR: Check-size had little effect on evoked responses when the retina was stimulated 12.5–27.5° from the fovea, and the assumed size of retinal receptive field centers at different eccentricities in animals and humans was discussed.
145 citations
TL;DR: Comparisons of foveal cell densities across species showed an increase in the average number of cells/visual degree2 with increasing eye size; similarly, an increase occurred in receptor nuclei relative to ganglion cell density; thus, smaller eyes showed a coarser retinal grain and a lower 'concidence ratio' of receptors toganglion cells than was found in the largest eyes.
Abstract: The foveas of nine avian species, initially selected for the presence of a deep fovea and representing a wide range of eye sizes and ecological habits, were studied with quantitative light microscope techniques. Considerable variation was observed in the location and configuration of the avian foveas, although they appeared to be 'convexiclivate' in shape when compared with the fovea of the rhesus monkey. Comparisons of foveal cell densities (receptor nuclei and ganglion cells) across species showed an increase in the average number of cells/visual degree2 with increasing eye size; similarly, an increase occurred in receptor nuclei relative to ganglion cell density. Thus, smaller eyes showed a coarser retinal grain and a lower 'concidence ratio' of receptors to ganglion cells than was found in the largest eyes. There appeared to be no relationship between receptor densities/mm2 and (a) eye size, (b) depth of foveal clivus, or (c) width of foveal clivus. However, a negative correlation was generally observed between the width of the foveal clivus and eye size. Two foveas were seen in the red-tailed hawk, goshawk, sparrow hawk, and least tern. The central fovea was more differentiated, with greate densities of both receptor nuclei and ganglion cells than was observed in the emporal fovea of the same species. Further conclusions, particularly with respect to potential visual acuity, await quantitative measurements of foveal cone densities across species.
145 citations
TL;DR: More work is needed to confirm the developmental link between the size of the FAZ and the degree of foveal pit excavation, and to understand the relationship between these and other anatomic features of the humanfoveal region, including peak cone density, rod-free zone diameter, and Henle fiber layer.
Abstract: PURPOSE. To assess the relationship between foveal pit morphology and size of the foveal avascular zone (FAZ). METHODS. Forty-two subjects were recruited. Volumetric images of the macula were obtained using spectral domain optical coherence tomography. Images of the FAZ were obtained using either a modified fundus camera or an adaptive optics scanning light ophthalmoscope. Foveal pit metrics (depth, diameter, slope, volume, and area) were automatically extracted from retinal thickness data, whereas the FAZ was manually segmented by two observers to extract estimates of FAZ diameter and area. RESULTS. Consistent with previous reports, the authors observed significant variation in foveal pit morphology. The average foveal pit volume was 0.081 mm 3 (range, 0.022 to 0.190 mm 3 ). The size of the FAZ was also highly variable between persons, with FAZ area ranging from 0.05 to 1.05 mm 2 and FAZ diameter ranging from 0.20 to 1.08 mm. FAZ area was significantly correlated with foveal pit area, depth, and volume; deeper and broader foveal pits were associated with larger FAZs. CONCLUSIONS. Although these results are consistent with predictions from existing models of foveal development, more work is needed to confirm the developmental link between the size of the FAZ and the degree of foveal pit excavation. In addition, more work is needed to understand the relationship between these and other anatomic features of the human foveal region,
145 citations
TL;DR: The results of the present experiment suggest that, besides the difficulty of the peripheral selection task, fixation duration is an important factor determining the selection of potential targets for eye movements.
143 citations
TL;DR: The gap junctions observed between mammalian cones, including those in the human fovea, represent genuine electrical coupling, and the signal-to-noise ratio can be markedly improved before the nonlinear stages with little compromise to visual acuity.
143 citations