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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18 Dec 2002TL;DR: In this paper, a method for determining font characteristics by determining a character density for the font and multiplying the character density by a sharpest focusable area of the viewing medium is presented.
Abstract: A system and method determines an optimum size for a font for readability. A method determines font characteristics by determining a character density for the font and multiplying the character density by a sharpest focusable area of the viewing medium. The method further includes varying the character density according to a range in a number of clusters per fixation to determine a maximum font size and a minimum font size. In an embodiment, the character density is a ratio of a number of clusters per em in the font to a number of visible clusters within a predetermined foveal angle. The predetermined foveal angle can be a field of vision for sharpest focus of an eye or a reader specific foveal angle that reflects the reader's visual acuity, taking into consideration macular degeneration, vision impairments, vision sharpness, tunnel vision, eye disease, near sightedness, far sightedness, dyslexia, and astigmatism.
32 citations
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TL;DR: The SD-OCT staging system according to the presence of EIFL is effective for grading retinal damage and visual loss in eyes with ERM.
Abstract: To evaluate the relationship between the presence of ectopic inner foveal layers (EIFL), choroidal thickness, and visual acuity (VA) in patients with epiretinal membranes (ERM) staged by spectral-domain optical coherence tomography (SD-OCT). A total of 242 eyes of 121 patients with unilateral idiopathic ERM were prospectively evaluated. ERM stages were defined based on the SD-OCT staging system as stage 1: negligible morphological or anatomical disruption, retinal layers, and foveal pit are identified; stage 2: characteristic stretching of the outer nuclear layer, absence of foveal depression, retinal layers are identified; stage 3: continuous EIFL crossing the central foveal area, absence of foveal depression, retinal layers are identified; and stage 4: anatomical disruption of the fovea, continuous EIFL crossing the entire foveal area, retinal layers are distorted. Of 121 eyes with ERM, 23.1% had stage 1, 26.5% had stage 2, 39.7% had stage 3, and 10.7% had stage 4 disease. VA was better in eyes with stage 1 or 2 ERM than stage 3 or 4 ERM (p 0.05). The SD-OCT staging system according to the presence of EIFL is effective for grading retinal damage and visual loss in eyes with ERM.
32 citations
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TL;DR: A scale‐invariant superiority of foveal vision for learning object categories implies a high degree of space variance of visual cognition which is vastly underestimated by classical measures of visual performance, e.g. acuity, visual field and contrast sensitivity.
Abstract: The recognition of objects is exceedingly difficult in indirect view. This complication cannot be explained in terms of retino-cortical magnification, as size scaling fails to establish position invariance both for character recognition [Strasburger, H. & Rentschler, I. (1996) Eur. J. Neurosci., 8 1787-1791] and pattern classification [Juttner, M. & Rentschler, I. (1996) Vision Res., 36, 1007-1021]. Thus we compared, for two tasks of discrimination learning and category learning with respect to a common set of grey-level patterns, how humans perform in foveal and extrafoveal vision. Observers learnt to discriminate (size-scaled) images equally well in foveal and extrafoveal view, whereas they displayed profound deficiencies in extrafoveal category learning for the same patterns. From the behavioural learning data, internal representations of the learning signals were reconstructed by means of computer simulations. For foveal view, these representations were found to be veridical to their physical counterparts for both learning tasks. For extrafoveal view, they were severely distorted for category learning but not for discrimination learning. A variance reduction of the pattern classes by a factor of 100 reduced the dissociation between extrafoveal categorization and discrimination but did not remove it. These observations suggest a scale-invariant superiority of foveal vision for learning object categories. This implies a high degree of space variance of visual cognition which is vastly underestimated by classical measures of visual performance, e.g. acuity, visual field and contrast sensitivity.
32 citations
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TL;DR: It is concluded that the foveal LERG may be used as a stable and reliable indicator of receptor function.
32 citations
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TL;DR: A tentative model of information processing in the human fovea at photopic luminances is described, that handles both luminosity and chromaticity signals and an attempt is made to locate the components of the model in the anatomical structure of the retina.
Abstract: A tentative model of information processing in the human fovea at photopic luminances is described, that handles both luminosity and chromaticity signals. The model consists of a “scaling-ensemble”, a group of sealers with common scaling-factor that provide an effective compression of the dynamic range of the input signals. The scaling factor adapts in such a way that the model conforms to Weber's law for the detection of short, small flashes on a bright background. The dynamics of the adaptation is such that the model effectively computes the logarithmic time derivative of the input signal. The model predicts the outcome of several psychophysical experiments. The predictions include Weber's law, Bloch's law, the apparent brightness of suprathreshold flashes as a function of adaptation level, the influence of spatial inhomogeneities on the perception of flicker, and the transfer function for moving sinusoidal bar patterns for both luminosity and chromaticity modulations. The influence of involuntary eye-movements on the perception of spatial patterns is also discussed. Finally an attempt is made to locate the components of the model in the anatomical structure of the retina. A tentative scheme of neural connections in the human fovea is presented.
32 citations