Showing papers on "Foveal published in 2008"
TL;DR: It is shown that a foveal pit is not required for foveAL cone specialization, anatomically or functionally, and this helps to explain the potential for good acuity in the absence of a pit and raises questions about the visual role of the fovea plana.
Abstract: Objectives To elucidate the visual significance of the foveal pit by measuring foveal architecture and function and to reassess use of the termfoveal hypoplasia(as visual acuity can vary among patients who lack a pit). Methods We describe 4 patients who lack a foveal pit. Visual acuities ranged from 20/20 to 20/50. Stratus and Cirrus (Carl Zeiss Meditec, Dublin, California) optical coherence tomographs (OCTs) and multifocal electroretinograms were obtained. High-resolution retinal imaging on 2 of the participants was obtained by using a high-resolution Fourier-domain OCT and an adaptive optics flood-illuminated fundus camera. Results No participants had a visible foveal pit with conventional OCT. Central widening of the outer nuclear layer and lengthening of cone outer segments were seen with high-resolution Fourier-domain OCT. Adaptive optics imaging showed normal cone diameters in the central 1° to 2°. Central multifocal electroretinogram responses were normal. Conclusions We show that a foveal pit is not required for foveal cone specialization, anatomically or functionally. This helps to explain the potential for good acuity in the absence of a pit and raises questions about the visual role of the foveal pit. Because the term foveal hypoplasia commonly carries a negative functional implication, it may be more proper to call the anatomic lack of a pitfovea plana.
205 citations
TL;DR: It is found that the pattern of functional magnetic resonance imaging response in human foveal retinotopic cortex contained information about objects presented in the periphery, far away from the fovea, which has not been predicted by prior theories of feedback.
Abstract: The mammalian visual system contains an extensive web of feedback connections projecting from higher cortical areas to lower areas, including primary visual cortex. Although multiple theories have been proposed, the role of these connections in perceptual processing is not understood. We found that the pattern of functional magnetic resonance imaging response in human foveal retinotopic cortex contained information about objects presented in the periphery, far away from the fovea, which has not been predicted by prior theories of feedback. This information was position invariant, correlated with perceptual discrimination accuracy and was found only in foveal, but not peripheral, retinotopic cortex. Our data cannot be explained by differential eye movements, activation from the fixation cross, or spillover activation from peripheral retinotopic cortex or from lateral occipital complex. Instead, our findings indicate that position-invariant object information from higher cortical areas is fed back to foveal retinotopic cortex, enhancing task performance. The authors report that fMRI responses in human foveal retinotopic cortex contain information about objects presented in the periphery. This information is position invariant and correlated with perceptual discrimination accuracy.
192 citations
TL;DR: The foveas of subjects with a history of mild ROP have significant structural abnormalities that are probably a consequence of perturbations of neurovascular development.
Abstract: The fovea, which mediates the excellent visual acuity enjoyed by healthy adults, is characterized by an absence of retinal vasculature, a high density of elongated cone inner and outer segments, and a pit without overlying ganglion cell or inner nuclear layers. The fovea is the last retinal region to reach maturity.1 During the development of the central retina, the fovea forms in a rod-free zone that decreases in diameter as the cone inner segments become more slender, outer segments elongate, and the cones pack tightly together.2,3 A ring of parafoveal vasculature defines a central avascular zone (AZ) and the developing foveal dimple.4,5 The protracted course of central retinal and foveal development continues after birth into early childhood as neural and vascular elements take their proper places.6,7 Knowledge of development of the normal central retina and foveal structure has depended heavily on anatomic studies of the simian retina6,8,9 with fewer observations on the human fovea.2,3 Retinopathy of prematurity (ROP) is known to alter development of the central retina and, even if mild, may be associated with deficits in acuity and visual sensitivity.10–12 However, foveal fine structure in ROP has yet to be studied. So far, imaging the living macula in human subjects with a history of ROP has yielded only coarse information about foveal structure.13
The advent of high-speed, high-resolution retinal imaging enables investigation of the central retina in the living human eye with nearly the same fidelity as traditional histology. New technologies include optical coherence tomography (OCT), in which optical cross-sections with high axial resolution are generated14; Fourier domain OCT, a high-speed, multiplexed version of OCT15,16; and adaptive optics (AO), which overcomes a fundamental limitation on lateral resolution imposed by ocular aberrations.17–19 In combination, these technologies provide the ability to visualize microstructures in the living eye.20,21 We used adaptive optics–Fourier domain optical coherence tomography (AO-FDOCT) to investigate the fine structure of the central retina in subjects with ROP.
179 citations
TL;DR: Using functional magnetic resonance imaging, it was found that the spatial distribution of V1 activity induced by the far ring was also shifted toward a more eccentric representation of the visual field, whereas that inducing by the close ring was shifted toward the foveal representation, consistent with their perceptual appearances.
156 citations
TL;DR: Functional magnetic resonance imaging was used to assess abnormal cortical signals in humans with juvenile macular degeneration to assess large-scale cortical reorganization and observed highly significant responses in the LPZ while they performed stimulus-related judgments.
Abstract: We used functional magnetic resonance imaging to assess abnormal cortical signals in humans with juvenile macular degeneration (JMD). These signals have been interpreted as indicating large-scale cortical reorganization. Subjects viewed a stimulus passively or performed a task; the task was either related or unrelated to the stimulus. During passive viewing, or while performing tasks unrelated to the stimulus, there were large unresponsive V1 regions. These regions included the foveal projection zone, and we refer to them as the lesion projection zone (LPZ). In 3 JMD subjects, we observed highly significant responses in the LPZ while they performed stimulus-related judgments. In control subjects, where we presented the stimulus only within the peripheral visual field, there was no V1 response in the foveal projection zone in any condition. The difference between JMD and control responses can be explained by hypotheses that have very different implications for V1 reorganization. In controls retinal afferents carry signals indicating the presence of a uniform (zero-contrast) region of the visual field. Deletion of retinal input may 1) spur the formation of new cortical pathways that carry task-dependent signals (reorganization), or 2) unmask preexisting task-dependent cortical signals that ordinarily are suppressed by the deleted signals (no reorganization).
142 citations
TL;DR: It is concluded that large-scale reorganization of visual processing in MD occurs only in the complete absence of functional foveal vision.
136 citations
TL;DR: In this paper, the authors studied the correlation of visual acuity and the thickness of the foveal photoreceptor layer in eyes with persistent cystoid macular edema associated with branch retinal vein occlusion.
129 citations
TL;DR: The foveal region is normally avascular during development, as in adult life, and there is no evidence offoveal vascularization during development of the human retina.
Abstract: Objective To study the development of the perifoveal retinal vasculature. Methods We studied 7 retinas aged between 26 weeks' gestation and 1 week postnatal (41 weeks' gestation). Sections were imaged using high-resolution digital photography and blood vessel profiles identified at 200% to 300% magnification. Flat mounts were immunolabeled using antibodies to CD31 and factor VIII to identify blood vessels and antibodies to rhodopsin to identify the rod-free zone. Results The foveal region was identified by the absence of rod photoreceptors in the outer retina and/or presence of a shallow depression in the inner retina. The whole mount at 26 weeks' gestation showed a blood vessel–free region centered on the rod-free zone that was open along the horizontal meridian on the temporal side. At 37 weeks' gestation, the foveal avascular zone formed a complete circle. In sections, the foveal avascular zone was approximately 500 μm in diameter at 35 weeks' gestation and 300 to 350 μm at 40 weeks' gestation; in whole mounts, it was 150 to 170 μm in diameter at 37 and 41 weeks' gestation. Conclusions The foveal region is normally avascular during development, as in adult life. We found no evidence of foveal vascularization during development of the human retina. Clinical Relevance Instances of vascularization of the foveal region are not due to failed regression of a transient vasculature.
129 citations
TL;DR: A limited parafoveal-on-foveal effect was observed: There were inflated fixation times on wordn when the preview of wordn + 1 was orthographically illegal, and this effect was associated with relatively long prior saccades.
Abstract: Contrasting predictions of serial and parallel views on the processing of foveal and parafoveal information during reading were tested. A high-frequency adjective (young) was followed by either a high-frequency wordn (child) or a low-frequency wordn (tenor), which in turn was followed by either a correct (performing) or an orthographic illegal wordn + 1 (pxvforming) as a parafoveal preview. A limited parafoveal-on-foveal effect was observed: There were inflated fixation times on wordn when the preview of wordn + 1 was orthographically illegal. However, this parafoveal-on-foveal effect was (a) independent of the frequency of wordn, (b) restricted to those instances when the eyes were very close to wordn + 1, and (c) associated with relatively long prior saccades. These observations are all compatible with a mislocated fixation account in which parafoveal-on-foveal effects result from saccadic undershoots of wordn + 1 and with a serial model of eye movement control during reading.
128 citations
TL;DR: Individual differences in eye movements during picture viewing were examined across image format, content, and foveal quality in 3 experiments and showed a great deal of consistency within individuals when viewing different types of images.
Abstract: Individual differences in eye movements during picture viewing were examined across image format, content, and foveal quality in 3 experiments. Experiment 1 demonstrated that an individual's fixation durations were strongly related across 3 types of scene formats and that saccade amplitudes followed the same pattern. In Experiment 2, a similar relationship was observed for fixation durations across faces and scenes, although the amplitude relationship did not hold as strongly. In Experiment 3, the duration and amplitude relationships were observed when foveal information was degraded and even removed. Eye movement characteristics differ across individuals, but there is a great deal of consistency within individuals when viewing different types of images.
122 citations
TL;DR: After resolution of the ME associated with central retinal vein occlusion, visual acuity is closely associated with integrity of the foveal photoreceptor layer.
Abstract: PURPOSE To study the correlation between final visual acuity and integrity of the foveal photoreceptor layer after resolution of macular edema (ME) associated with central retinal vein occlusion (CRVO). METHODS We studied retrospectively 27 eyes of 27 patients with resolved ME associated with central retinal vein occlusion. On optical coherence tomography, integrity of the foveal photoreceptor layer was studied using the junctions between inner and outer segments of the photoreceptor (IS/OS) line as a hallmark. RESULTS At the final visit, foveal thickness was decreased to a physiologic level in all eyes. On optical coherence tomography, 14 eyes showed the IS/OS line in the fovea, whereas 13 eyes showed no IS/OS line. In concordance with resolution of the ME, visual acuity had improved significantly by the final visit. However, final visual acuity in eyes without an IS/OS line was significantly poorer than that in eyes with an IS/OS line (P < 0.0001). In addition, integrity of the foveal photoreceptor layer after resolution of the ME had a significant correlation with the initial retinal perfusion status (P = 0.0156) and with initial visual acuity (P = 0.0050). CONCLUSIONS After resolution of the ME associated with central retinal vein occlusion, visual acuity is closely associated with integrity of the foveal photoreceptor layer.
TL;DR: The experiment established that incongruous objects attract eye fixations earlier than the congruous counterparts, but that this effect is not apparent until the picture has been displayed for several seconds, and a model of scene perception is suggested.
TL;DR: Foveal MP was positively and significantly related to foveal width in the entire study group and may be determined by the greater length of the cone axons (Henle fibers) in wider foveas.
Abstract: PURPOSE Macular pigment (MP) is composed of two dietary carotenoids, lutein and zeaxanthin, and a carotenoid generated by the retina, meso-zeaxanthin. There is large intersubject variability in peak optical density, spatial profile, and lateral extent of macular pigment, and it has been suggested that foveal architecture may play a role in this variability. This study is an initial investigation of the relationship between the spatial profile of macular pigment and foveal architecture. METHODS Sixty normal subjects were enrolled (one was eventually excluded). The spatial profile of macular pigment optical density (MPOD) was measured by customized heterochromatic flicker photometry (cHFP). High-resolution macular thickness maps were obtained by optical coherence tomography. Four parameters were analyzed: (1) minimum foveal thickness (MFT) at the intersection of six radial scans; (2) central foveal thickness (CFT) averaged over the central 1 mm of the fovea; (3) foveal width identified as the region lacking a nerve fiber layer; and (4) foveal width measured from crest to crest. Lifestyle and vision information were obtained by questionnaire. RESULTS The mean +/- SD MPOD at 0.25 degrees eccentricity was 0.49 +/- 0.23 and at 0.5 degrees eccentricity, 0.41 +/- 0.21. A first-order decreasing exponential function accounted for most of the variance of the MP profile averaged across subjects (r(2) = 0.99). MPOD measured at 0.25 degrees was unrelated to both measures of foveal thickness for the entire study group (r = 0.03, P = 0.81, and r = -0.08, P = 0.57, respectively). Similarly, MPOD measured at 0.5 degrees was unrelated to foveal thickness in the entire study group (r = 0.12, P = 0.36 and r = -0.05, P = 0.71, respectively). However, when analyzed separately in the nonwhite subjects, the relationship between MPOD at 0.25 degrees and MFT was positive and significant (r = 0.59, P = 0.01), but remained unrelated to CFT (r = 0.20, P = 0.41). Similarly, in the nonwhite subjects, the relationship between MPOD at 0.5 degrees and MFT was positive and significant (r = 0.68, P < 0.01), but again was unrelated to CFT (r = 0.23, P = 0.32). There was no significant relationship between MPOD and either measure of foveal thickness in the white subjects. In the entire study group, there was a positive and significant relationship between foveal width and MPOD averaged across the fovea (r = 0.41, P < 0.01) and between foveal width and MP integrated across the fovea (r = 0.41, P < 0.01). CONCLUSIONS Foveal MP was positively and significantly related to foveal width in the entire study group. This relationship may be determined by the greater length of the cone axons (Henle fibers) in wider foveas. MPOD was unrelated to foveal thickness in the white subjects. However, in the nonwhite subjects there was a positive association between MFT and MPOD at the 0.25 degrees and 0.5 degrees eccentricities, suggesting that other personal characteristics modulate the MPOD-retinal thickness relationship.
12 Dec 2008
TL;DR: A no-reference perceptual sharpness quality metric, inspired by visual attention information, is presented for a better simulation of the Human Visual System response to blur distortions.
Abstract: A no-reference perceptual sharpness quality metric, inspired by visual attention information, is presented for a better simulation of the Human Visual System (HVS) response to blur distortions. Saliency information about a scene is used to accentuate blur distortions around edges present in conspicuous areas and attenuate those distortions present in the rest of the image. Simulation results are presented to illustrate the performance of the proposed metric.
TL;DR: There is a vast difference in availability of information about head direction and eye direction, both of which can serve as indicators of the looker's focus of attention, which is important for understanding the dynamics of eye-gaze behavior.
Abstract: Two psychophysical experiments are reported, one dealing with the visual perception of the head orientation of another person (the 'looker') and the other dealing with the percep- tion of the looker's direction of eye gaze. The participant viewed the looker with different retinal eccentricities, ranging from foveal to far-peripheral viewing. On average, judgments of head orientation were reliable even out to the extremes of peripheral vision (908 eccentricity), with better performance at the extremes when the participant was able to view the looker changing head orientation from one trial to the next. In sharp contrast, judgments of eye-gaze direction were reliable only out to 48 eccentricity, signifying that the eye-gaze social signal is available to people only when they fixate near the looker's eyes. While not unexpected, this vast difference in availability of information about head direction and eye direction, both of which can serve as indicators of the looker's focus of attention, is important for understanding the dynamics of eye-gaze behavior.
TL;DR: The flexibility with which activity across the SC represents the location, as well as the spatial precision, of behaviorally relevant goals for multiple eye movements is demonstrated.
Abstract: The primate superior colliculus (SC) has long been known to be involved in saccade generation. However, SC neurons also exhibit fixation-related and smooth-pursuit-related activity. A parsimonious explanation for these seemingly disparate findings is that the SC contains a map of behaviorally relevant goal locations, rather than just a motor map for saccades and fixation. This explanation predicts that SC activity should reflect the behavioral goal, even when the behavioral response is not fixation or saccades, and even if the goal does not correspond to a visual stimulus. We tested this prediction by using a tracking task that dissociates the stimulus and goal locations. In this task, monkeys tracked the invisible midpoint between two peripheral bars, such that the visual stimuli were peripheral but the goal was foveal/parafoveal. We recorded from SC neurons representing peripheral locations associated with the stimulus or central locations associated with the goal. Most neurons with peripheral response fields did not respond differently during tracking than during passive viewing of the stimulus under fixation; most neurons with central response fields responded more during tracking than during fixation, despite the lack of a visual stimulus. Moreover, the spatial distribution of activity during tracking was larger than that during fixation or tracking of a foveal stimulus, suggesting that the greater spatial uncertainty about the invisible goal corresponded to more widespread SC activity. These results demonstrate the flexibility with which activity across the SC represents the location, as well as the spatial precision, of behaviorally relevant goals for multiple eye movements.
TL;DR: It is concluded that the specific content of emotional or neutral scenes is not processed in peripheral vision, and a coarse impression of emotional scenes may be extracted, which then leads to selective attentional orienting or--in the absence of overt attention--causes false alarms for related probes.
Abstract: Emotional-neutral pairs of visual scenes were presented peripherally (with their inner edges 5.2 degrees away from fixation) as primes for 150 to 900 ms, followed by a centrally presented recognition probe scene, which was either identical in specific content to one of the primes or related in general content and affective valence. Results indicated that (a) if no foveal fixations on the primes were allowed, the false alarm rate for emotional probes was increased; (b) hit rate and sensitivity (A') were higher for emotional than for neutral probes only when a fixation was possible on only one prime; and (c) emotional scenes were more likely to attract the first fixation than neutral scenes. It is concluded that the specific content of emotional or neutral scenes is not processed in peripheral vision. Nevertheless, a coarse impression of emotional scenes may be extracted, which then leads to selective attentional orienting or--in the absence of overt attention--causes false alarms for related probes.
TL;DR: Foveal-sparing scotomas are common in advanced dry macular degeneration (geographic atrophy) and may be present for a number of years, and patients have reduced reading rates.
Abstract: Foveal-sparing scotomas are common in advanced dry macular degeneration (geographic atrophy). Foveal preservation may be present for a number of years. Despite good visual acuity, these patients have reduced reading rates. Magnification may not be effective if the text becomes too large to "fit" within the central spared area.
TL;DR: A subnormal foveal thickness in type 2 IMT may be associated with better macular function as assessed by microperimetry, and the correlation of light sensitivity and visual acuity with retinal thickness was reduced.
TL;DR: Evidence for the universality of the global effect, i.e. the general tendency to move the eyes towards the centre of gravity of the peripheral configu-ration, is reviewed, and it is shown that the effect is strongly constrained by the retinal location of the stimuli.
Abstract: In the present paper, I review evidence for the universality of the global effect, i.e. the general tendency to move the eyes towards the centre of gravity of the peripheral configu-ration, and show that the effect is strongly constrained by the retinal location of the stimuli. First, stimuli that are displayed in a central foveal region of a 1-1.5° radius fail to deviate the eyes in a centre-of-gravity manner; this is referred to as the foveal dead zone. Second, the stimuli that are too eccentric relative to the saccade target and/or the main stimulation site are filtered out. These limitations reflect physiological constraints and the dynamics of the patterns of activity in a visual saliency map. They form the basis for a low-level centre-of-gravity type account of eye guidance in natural perceptual tasks such as reading.
TL;DR: Following phacoemulsification, an increase in the foveal thickness was detected in the early postoperative period, quantified and followed up by OCT, and no association was shown between intraoperative parameters and increased postoperative retinal thickness.
Abstract: Background
Despite a significant body of research, no consistency on postoperative foveal thickness as measured by optical coherence tomography (OCT), can be recorded. The purpose of our study was to evaluate the effect of uncomplicated cataract surgery in the thickness of the retina in the foveal area during the early postoperative period.
TL;DR: OCT findings for nanophthalmic eyes with foveal underdevelopment are different from posterior microphthalmos and fveal hypoplasia seen in other disorders, and the new measure RFD is a useful tool in ocular tomography.
Abstract: PURPOSE: To describe the optical coherence tomography (OCT) findings for nanophthalmic eyes. METHODS: : In this retrospective, single-center, observational case series, 15 patients (28 eyes) with axial lengths of
TL;DR: The result reveals that the affective significance of emotional stimuli can be assessed early through covert attention mechanisms, in the absence of overt eye fixations on the stimuli, and suggests that right-hemisphere dominance is involved.
Abstract: This study investigated whether stimulus affective content can be extracted from visual scenes when these appear in parafoveal locations of the visual field and are foveally masked, and whether there is lateralization involved. Parafoveal prime pleasant or unpleasant scenes were presented for 150 msec 2.5° away from fixation and were followed by a foveal probe scene that was either congruent or incongruent in emotional valence with the prime. Participants responded whether the probe was emotionally positive or negative. Affective priming was demonstrated by shorter response latencies for congruent than for incongruent prime-probe pairs. This effect occurred when the prime was presented in the left visual field at a 300-msec prime-probe stimulus onset asynchrony, even when the prime and the probe were different in physical appearance and semantic category. This result reveals that the affective significance of emotional stimuli can be assessed early through covert attention mechanisms, in the absence of overt eye fixations on the stimuli, and suggests that right-hemisphere dominance is involved.
TL;DR: This article showed that mislocated fixations cannot plausibly act within the architecture of a serial model to produce effects mimicking parafoveal-on-foveal cross-talk.
Abstract: Oculomotor error leads to a proportion of saccades during reading missing the intended target. In this paper two kinds of mislocation are identified: either a word is erroneously refixated, or a word that was about to skipped is erroneously fixated. In both cases recorded fixation duration could be influenced by the fact that the overt fixation reflects neither the reader’s intentions, not the current locus of attention. It has been argued that mislocations of this kind account for apparent “parafoveal-on-foveal” interactions and that, consequently, the challenge posed by such effects for serial processing models of eye movement control is more apparent than real. It is argued here that this analysis is flawed: mislocated fixations cannot plausibly act within the architecture of a serial model to produce effects mimicking parafoveal-on-foveal cross-talk. The claim that parafoveal-on-foveal effects are restricted to measurements made when the eyes are very close to the relevant parafoveal target is not supported in an analysis of the effects of cumulative lexical frequency on foveal processing time.
TL;DR: An algorithm is presented for processing and analysis of differential interference contrast (DIC) microscopy images of the fovea to study the cone mosaic and additional algorithms are presented that analyze the cone positions to extract information on cone neighbor relationships as well as the short-range order and domain structure of the mosaic.
Abstract: An algorithm is presented for processing and analysis of differential interference contrast (DIC) microscopy images of the fovea to study the cone mosaic. The algorithm automatically locates the cones and their boundaries in such images and is assessed by comparison with results from manual analysis. Additional algorithms are presented that analyze the cone positions to extract information on cone neighbor relationships as well as the short-range order and domain structure of the mosaic. The methods are applied to DIC images of the human fovea.
TL;DR: The abnormalities in cortical architecture are interpreted in terms of the absence of the fovea, the common retinal feature found in both groups, and it is shown that the calcarine fissure, where the primary visual cortex is represented, is abnormally short in those lacking a foveA.
Abstract: The foveal region contains the highest cell density in the human retina; consequently a disproportionately large area of the visual cortex is dedicated to its representation. In aniridia and albinism the fovea does not develop, and the corresponding cortical representation shows a reduction in gray matter volume. In albinos there are chiasmatic irregularities in the hemispheric projections, which are not found in aniridics. Here, we ask whether the anomalies in central retinal development, present in albinism and aniridia, have a wider impact on the architecture of the visual cortex. The length, depth, and topology of the calcarine fissure is analyzed in albino, aniridic, and normal subjects. These measures are compared between groups and between the cortical hemispheres within each subject. We show that the calcarine fissure, where the primary visual cortex is represented, is abnormally short in those lacking a fovea. Moreover, surface reconstructions of the calcarine fissure revealed marked interhemispheric asymmetries. The two groups could not be distinguished on the basis of their cortical features, and we therefore interpret the abnormalities in cortical architecture in terms of the absence of the fovea, the common retinal feature found in both groups.
TL;DR: Findings support the well-established view that words encountered outside foveal vision project to different, contralateral hemispheres but indicate that this division for word recognition occurs only outside the fovea and provide no support for the claim that a functional split in hemispheric processing exists at the point of fixation.
Abstract: Several studies have claimed that hemispheric asymmetries affect word recognition right up to the point of fixation because each fovea is split precisely at its vertical midline and information presented either side of this midline projects unilaterally to different, contralateral hemispheres. To investigate this claim, four-letter words were presented to the left or right of fixation, either close to fixation entirely in foveal vision (0.15, 0.25, and 0.35 degrees from fixation) or further from fixation entirely in extrafoveal vision (2.00, 2.10, and 2.20 degrees from fixation). Fixation location and stimulus presentation were controlled using an eye-tracker linked to a fixation-contingent display and performance was assessed using a forced-choice task to suppress confounding effects of guesswork. A left hemisphere advantage was observed for words presented in extrafoveal locations but no hemisphere advantage (left or right) was observed for words presented in any foveal location. These findings support the well-established view that words encountered outside foveal vision project to different, contralateral hemispheres but indicate that this division for word recognition occurs only outside the fovea and provide no support for the claim that a functional split in hemispheric processing exists at the point of fixation.
Patent•
05 Nov 2008TL;DR: In this paper, a parallel processing architecture that uses reprogrammable logic to implement embedded, distributed, real-time foveal image processing from different sensor types while simultaneously allowing for lossless storage and retrieval of raw image data is described.
Abstract: Apparatuses and methods are disclosed that create a synthetic fovea in order to identify and highlight interesting portions of an image for further processing and rapid response. Synthetic foveal imaging implements a parallel processing architecture that uses reprogrammable logic to implement embedded, distributed, real-time foveal image processing from different sensor types while simultaneously allowing for lossless storage and retrieval of raw image data. Real-time, distributed, adaptive processing of multi-tap image sensors with coordinated processing hardware used for each output tap is enabled. In mosaic focal planes, a parallel-processing network can be implemented that treats the mosaic focal plane as a single ensemble rather than a set of isolated sensors. Various applications are enabled for imaging and robotic vision where processing and responding to enormous amounts of data quickly and efficiently is important.
TL;DR: To describe different techniques for the detection of diabetic foveal edema, optical coherence tomography measurements can detect early retinal damage in diabetic retinopathy patients.
Abstract: To describe different techniques for the detection of diabetic foveal edema. A retrospective review of the detection of diabetic foveal edema. Noncontact lens biomicroscopy is relatively insensitive in mild foveal thickening apparent on optical coherence tomography. Optical coherence tomography measurements can detect early retinal damage in diabetic retinopathy patients.