Entire Visual Field Research Articles

Uniformity and diversity of response properties of neurons in the primary visual cortex: Selectivity for orientation, direction of motion, and stimulus size from center to far periphery

Although the primary visual cortex (V1) is one of the most extensively studied areas of the primate brain, very little is known about how the far periphery of visual space is represented in this area. We characterized the physiological response properties of V1 neurons in anaesthetized marmoset monkeys, using high-contrast drifting gratings. Comparisons were made between cells with receptive fields located in three regions of V1, defined by eccentricity: central (3-5°), near peripheral (5-15°), and far peripheral (>50°). We found that orientation selectivity of individual cells was similar from the center to the far periphery. Nonetheless, the proportion of orientation-selective neurons was higher in central visual field representation than in the peripheral representations. In addition, there were similar proportions of cells representing all orientations, with the exception of the representation of the far periphery, where we detected a bias favoring near-horizontal orientations. The proportions of direction-selective cells were similar throughout V1. When the center/surround organization of the receptive fields was tested with gratings with varying diameters, we found that the population of neurons that was suppressed by large gratings was smaller in the far periphery, although the strength of suppression in these cells tended to be stronger. In addition, the ratio between the diameters of the excitatory centers and suppressive surrounds was similar across the entire visual field. These results suggest that, superimposed on the broad uniformity of V1, there are subtle physiological differences, which indicate that spatial information is processed differently in the central versus far peripheral visual fields.

Persistent migraine aura in an adolescent girl

A 14-year-old girl presented with a prolonged migraine visual aura of several weeks' duration. Symptoms gradually resolved over a 6-week period, with no recurrence of visual aura over a 20-month follow-up period. Although there is significant overlap between the features of stereotypical and persistent migraine auras, or "visual snow," the latter tend to be unformed and can occupy the entire visual field of both eyes. To our knowledge, this phenomenon has been reported only twice before in children. Recognition of its features will allow the pediatric ophthalmologist to differentiate persistent visual aura from visual hallucinations.

The W-shaped pupil in cuttlefish (Sepia officinalis): Functions for improving horizontal vision

The eyes of cuttlefish (Sepia officinalis) have a modified horizontal slit-pupil with a distinctive W-shape in bright light, while in darkness the pupil is circular. Two suggestions have previously been made for a function of the W-shape: (1) camouflaging the eye; (2) providing distance information. Since neither of these suggestions can fully explain the function of this pupil across the entire visual field, particularly the frontal and caudal periphery, we re-addressed the question of its functional significance. We took infra-red images of the eyes of live S. officinalis at different light intensities and from different viewing angles. This allowed us to determine the shape and light-admitting area of the pupil for different parts of the visual field. Our data show that the W-shaped pupil projects a blurred “W” directly onto the retina and that it effectively operates as vertical slits for the frontal and caudal parts of the visual field. We also took images of the natural habitat of S. officinalis and calculated the average vertical brightness distribution in the visual habitat. Computing a retinal illumination map shows that the W-shaped pupil is effective in balancing a vertically uneven light field: The constricted pupil reduces light from the dorsal part of the visual field significantly more than it reduces light from the horizontal band. This will cut the amount of direct sunlight that is scattered by the lens and ocular media, and thus improve image contrast particularly for the dimmer parts of the scene. We also conclude that the pupil provides even attenuation along the horizontal band, whereas a circular pupil would attenuate the image relatively more in the important frontal and caudal periphery of the visual field.

Power spectra of the natural input to the visual system

The efficient coding hypothesis posits that sensory systems are adapted to the regularities of their signal input so as to reduce redundancy in the resulting representations. It is therefore important to characterize the regularities of natural signals to gain insight into the processing of natural stimuli. While measurements of statistical regularity in vision have focused on photographic images of natural environments it has been much less investigated, how the specific imaging process embodied by the organism’s eye induces statistical dependencies on the natural input to the visual system. This has allowed using the convenient assumption that natural image data are homogeneous across the visual field. Here we give up on this assumption and show how the imaging process in a human model eye influences the local statistics of the natural input to the visual system across the entire visual field. Artificial scenes with three-dimensional edge elements were generated and the influence of the imaging projection onto the back of a spherical model eye were quantified. These distributions show a strong radial influence of the imaging process on the resulting edge statistics with increasing eccentricity from the model fovea. This influence is further quantified through computation of the second order intensity statistics as a function of eccentricity from the center of projection using samples from the dead leaves image model. Using data from a naturalistic virtual environment, which allows generation of correctly projected images onto the model eye across the entire field of view, we quantified the second order dependencies as function of the position in the visual field using a new generalized parameterization of the power spectra. Finally, we compared this analysis with a commonly used natural image database, the van Hateren database, and show good agreement within the small field of view available in these photographic images. We conclude by providing a detailed quantitative analysis of the second order statistical dependencies of the natural input to the visual system across the visual field and demonstrating the importance of considering the influence of the sensory system on the statistical regularities of the input to the visual system.

Attention maps in the brain.

Over 20 distinct cerebral cortical areas contain spatial map representations of the visual field. These retinotopic, or visuotopic, cortical areas occur not only in the occipital lobe but also in the parietal, temporal, and frontal lobes. The cognitive influences of visuospatial attention operate via these cortical maps and can support selection of multiple objects at the same time. In early visual cortical areas, spatial attention enhances responses of selected items and diminishes the responses to distracting items. In higher order cortex, the maps support a spatial indexing role, keeping track of the items to be attended. These maps also support visual short-term memory (VSTM) representations. In each hemisphere, all the known maps respond selectively to stimuli presented within the contralateral visual field. However, a hemispheric asymmetry emerges when the attentional or VSTM demands of a task become significant. In the parietal lobe, the right hemisphere visuotopic maps switch from coding only contralateral visual targets to coding memory and attention targets across the entire visual field. This emergent asymmetry has important implications for understanding hemispatial neglect syndrome, and supports a dynamic network form of the representational model of neglect. WIREs Cogn Sci 2013, 4:327-340. doi: 10.1002/wcs.1230 This article is categorized under: Psychology > Attention Neuroscience > Cognition.

Optic disc progression and rates of visual field change in treated glaucoma

To investigate the relationship between optic disc progression and rates of visual field (VF) change in patients with treated glaucoma. Glaucoma patients with repeatable VF loss, ≥8 SITA-Standard 24-2 VF tests and good quality optic disc stereophotographs evaluated over a 10-year period were included. Optic disc photographs were reviewed for signs of glaucoma progression (neuroretinal rim change, widening of retinal nerve fibre layer defect, disc haemorrhage and enlargement of beta-zone parapapillary atrophy) by two glaucoma specialists masked to their temporal sequence. Disagreements were adjudicated by a third grader. VF progression was evaluated using automated pointwise linear regression (PLR) and defined as at least two adjacent test points progressing >1.0 dB/year at p < 0.01. VF progression outcomes were compared with photograph review results. Three-hundred and eighty nine eyes (389 patients; mean age 64.9 ± 13.0 years; mean baseline MD, -7.1 ± 5.1 dB) were included. Most patients had primary open angle glaucoma (54%). Eighty-two eyes (21%) had confirmed optic disc progression and 115 eyes (29%) met the VF PLR criteria. Eyes with documented optic disc progression had more rapid rates of VF change (-0.66 ± 0.7 versus -0.36 ± 0.7 dB/year, p < 0.01) and met the VF PLR endpoint more often (univariate OR = 1.85, p = 0.02; multivariate OR = 1.78, p = 0.03) than eyes without optic disc progression. There was moderate spatial consistency between the location of the optic disc progression and the hemifield with more rapid progression (81%, kappa = 0.40). Treated glaucomatous eyes with documented optic disc progression are at increased risk of diminished visual function over time and may require more aggressive therapy to prevent future vision loss. Among the indicators of structural progression, disc haemorrhage was the single most significant predictor for VF deterioration.

Anticipatory Remapping of Attentional Priority across the Entire Visual Field

It has been suggested that one way we may create a stable percept of the visual world across multiple eye movements is to pass information from one set of neurons to another around the time of each eye movement. Previous studies have shown that some neurons in the lateral intraparietal area (LIP) exhibit anticipatory remapping: these neurons produce a visual response to a stimulus that will enter their receptive field after a saccade but before it actually does so. LIP responses during fixation are thought to represent attentional priority, behavioral relevance, or value. In this study, we test whether the remapped response represents this attentional priority by examining the activity of LIP neurons while animals perform a visual foraging task. We find that the population responds more to a target than to a distractor before the saccade even begins to bring the stimulus into the receptive field. Within 20 ms of the saccade ending, the responses in almost one-third of LIP neurons closely resemble the responses that will emerge during stable fixation. Finally, we show that, in these neurons and in the population as a whole, this remapping occurs for all stimuli in all locations across the visual field and for both long and short saccades. We conclude that this complete remapping of attentional priority across the visual field could underlie spatial stability across saccades.

EPLERENONE ATTENUATES MYOCARDIAL FIBROSIS IN THE ANGIOTENSIN II-INDUCED HYPERTENSIVE MOUSE: INVOLVEMENT OF OSTEOPOTIN INDUCED BY NADPH OXIDASE

EPLERENONE ATTENUATES MYOCARDIAL FIBROSIS IN THE ANGIOTENSIN II-INDUCED HYPERTENSIVE MOUSE: INVOLVEMENT OF OSTEOPOTIN INDUCED BY NADPH OXIDASE

Does It Really Matter Where You Look When Walking on Stairs? Insights from a Dual-Task Study

Although the visual system is known to provide relevant information to guide stair locomotion, there is less understanding of the specific contributions of foveal and peripheral visual field information. The present study investigated the specific role of foveal vision during stair locomotion and ground-stairs transitions by using a dual-task paradigm to influence the ability to rely on foveal vision. Fifteen healthy adults (26.9±3.3 years; 8 females) ascended a 7-step staircase under four conditions: no secondary tasks (CONTROL); gaze fixation on a fixed target located at the end of the pathway (TARGET); visual reaction time task (VRT); and auditory reaction time task (ART). Gaze fixations towards stair features were significantly reduced in TARGET and VRT compared to CONTROL and ART. Despite the reduced fixations, participants were able to successfully ascend stairs and rarely used the handrail. Step time was increased during VRT compared to CONTROL in most stair steps. Navigating on the transition steps did not require more gaze fixations than the middle steps. However, reaction time tended to increase during locomotion on transitions suggesting additional executive demands during this phase. These findings suggest that foveal vision may not be an essential source of visual information regarding stair features to guide stair walking, despite the unique control challenges at transition phases as highlighted by phase-specific challenges in dual-tasking. Instead, the tendency to look at the steps in usual conditions likely provides a stable reference frame for extraction of visual information regarding step features from the entire visual field.

Remapping of attentional priority across the entire visual field

During natural vision, the positions of stationary objects change on the retina with each eye movement. However, our perception of the visual scene remains stable. It is thought that this stability arises, at least in part, by the visual system’s ability to update spatial information. It has been previously shown that neurons in the lateral intraparietal area (LIP) predictively respond to the presence of objects in their future receptive fields around the time of a saccade (Duhamel et al., 1992). However, it is unknown whether this remapping contains information about the priority of the objects or just about their location in space. Further, it is not known whether information about all objects is remapped or whether only information about an attended object is remapped. To investigate this, two animals were trained to perform a task in which they searched for a reward-loaded target among 10 objects consisting of targets and distractors. After the stimuli appeared, the subjects were free to move their eyes to find the reward-loaded target. Stimuli were spaced such that when looking at one stimulus, another was in the LIP neuron's receptive field. Responses of LIP neurons were significantly higher to targets compared to distracters. During fixation, the latency of this significant difference was at least 70 ms. When brought into the receptive field by a saccade, the latency of this difference appeared as quickly as 20 ms, showing a predictive remapping of stimulus priority. This short latency difference appeared across the entire visual field and was independent of eye movement direction and location. We suggest that the attentional priority across the entire visual field starts to be transferred to the future receptive field of neurons just before the initiation of the saccade and is significantly distinguishable shortly after the end of the saccade. Meeting abstract presented at VSS 2012

Validation of Point-Wise Exponential Regression to Measure the Decay Rates of Glaucomatous Visual Fields

This study was conducted to validate a recently described technique for measuring the rates of visual field (VF) decay in glaucoma. A pointwise exponential regression (PER) model was used to calculate average rates of faster and slower deteriorating VF components, and that of the entire VF. Rapid progressors had a faster component rate of >25%/year. Mean deviation (MD) and visual field index (VFI) forecasts were calculated by (1) extrapolation of linear regression of MD and VFI, and (2) calculation de novo from the PER-predicted final thresholds. The mean (± SD) years of follow-up and number of VFs were 9.2 (± 2.7) and 13.7 (± 5.8), respectively. The median rates of the decay were -0.1 and 3.6 (%/year) for the slower and the faster components, respectively. The "rapid progressors" (32% of eyes) had a mean decay rate of 52.2%/year. In comparison with actual values, the average absolute difference and the mean squared error for MD forecasts with linear extrapolation of indices were 3.58 dB and 31.91 dB(2), and with the de novo recalculation from PER predictions were 2.95 dB and 17.49 dB(2), respectively. Similar results were obtained for VFI forecasts. Comparisons of the prediction errors for both the MD and VFI favored the PER forecasts (P < 0.001). PER for measuring rates of VF decay is a robust indicator of rates across a wide range of disease severity and can predict future global indices accurately. The identification of "rapid progressors" identifies high-risk patients for appropriate treatment.

Interactive Visibility Retargeting in VR Using Conformal Visualization

In Virtual Reality, immersive systems such as the CAVE provide an important tool for the collaborative exploration of large 3D data. Unlike head-mounted displays, these systems are often only partially immersive due to space, access, or cost constraints. The resulting loss of visual information becomes a major obstacle for critical tasks that need to utilize the users' entire field of vision. We have developed a conformal visualization technique that establishes a conformal mapping between the full 360° field of view and the display geometry of a given visualization system. The mapping is provably angle-preserving and has the desirable property of preserving shapes locally, which is important for identifying shape-based features in the visual data. We apply the conformal visualization to both forward and backward rendering pipelines in a variety of retargeting scenarios, including CAVEs and angled arrangements of flat panel displays. In contrast to image-based retargeting approaches, our technique constructs accurate stereoscopic images that are free of resampling artifacts. Our user study shows that on the visual polyp detection task in Immersive Virtual Colonoscopy, conformal visualization leads to improved sensitivity at comparable examination times against the traditional rendering approach. We also develop a novel user interface based on the interactive recreation of the conformal mapping and the real-time regeneration of the view direction correspondence.

Bilateral atypical optic neuritis associated with tuberculosis in an immunocompromised patient

A 27 year-old lady, presented with sudden loss of vision in the right eye for a week. It was followed by poor vision in the left eye after 3 days. It involved the whole entire visual field and was associated with pain on eye movement. She was diagnosed to have miliary tuberculosis and retroviral disease 4 months ago. She was started on anti-TB since then but defaulted highly active anti-retroviral therapy (HAART). On examination, her visual acuity was no perception of light in the right eye and 6/120 (pinhole 3/60) in the left eye. Anterior segment in both eyes was unremarkable. Funduscopy showed bilateral optic disc swelling with presence of multiple foci of choroiditis in the peripheral retina. The vitreous and retinal vessels were normal. Chest radiography was normal. CT scan of orbit and brain revealed bilateral enhancement of the optic nerve sheath that suggest the diagnosis of bilateral atypical optic neuritis. This patient was managed with infectious disease team. She was started on HAART and anti-TB treatment was continued. She completed anti-TB treatment after 9 months without any serious side effects. During follow up the visual acuity in both eyes was not improved. However, funduscopy showed resolving of disc swelling and choroiditis following treatment.

Visual Snow: A New Disease Entity Distinct from Migraine Aura (S36.006)

Objective: To define clinical criteria for visual snow. Background Visual snow is a disorder with continuous visual symptoms consisting of white and black dots in the entire visual field that can persist for years. Additional visual phenomena might be present. It has a major impact on patients9 quality of life. The literature confounds the condition with persistent visual aura in migraine. Treatment usually fails. Physicians may regard the problem is trivial or psychogenic. Design/Methods: Retrospective survey of patients with visual snow. We describe the clinical phenotype of affected patients and propose criteria for the diagnosis. Results: Patients ( n = 120) with a female:male ratio of 1:2.2 are reported. Mean age of onset was 16.8±10.9 years with a mean duration of 9.1±10.3 years. Of patients 106 (88%) had visual snow during the daytime and 117 (98%) at Additional visual symptoms were: floaters (73%), persistent after-images (63%), hard time seeing at (58%), little cells that travel on a wiggly path (57%), photophobia (54%), moving objects leave trails (48%), flashes (44%), and swirls with eyes closed (41%). Most disturbing were visual snow, floaters and hard time seeing at night. Of patients 92% had no response to medication. Substance abuse was present in 40% of patients (LSD in 5%). Requiring at least one, two or three of the additional visual symptoms to make the diagnosis reduced the sensitivity by 3%, 10% and 21%. All standard tests were normal. Conclusions: (i) Visual snow, or Positive Persistent Visual Disturbance, is a unique disease entity presenting clinically distinct from migraine with aura.(ii) Criteria are: visual snow during daytime or at night plus at least one of the following: floaters, persistent after-images, hard time seeing at night, little cells that travel on a wiggly path, photophobia, moving objects leave trails, flashes, and swirls with eyes closed.(iii) Currently, the etiology is unknown. Supported by: Deutsche Forschungsgemeinschaft SCHA 1676/1-1. Disclosure: Dr. Schankin has nothing to disclose. Dr. Maniyar has nothing to disclose. Dr. Hoffmann has nothing to disclose. Dr. Chou has nothing to disclose. Dr. Goadsby has received personal compensation for activities with Allergan, Inc., Amgen Inc, Colucid, MAP Pharmaceuticals, MSD, Neuralieve, Neuraxon, ATI, Boehringer Ingelheim Pharmaceuticals, Inc., Boston Scientific, Coherex, Eli Lilly & Company, Medtronic, Inc., Linde, Bristol-Myers Squibb Company, Pfizer Inc, and Air Products. Dr. Goadsby has received research support from GlaxoSmithKline, Inc., Amgen Inc, MSD, Neuralieve, and Boston Scientific.

Associating the magnitude of relative afferent pupillary defect (RAPD) with visual field indices in glaucoma patients

PurposeTo identify the variable with the strongest association between the magnitude of the relative afferent pupillary defect (RAPD) and visual field indices in patients with glaucomatous optic neuropathy.MethodsSeventy-nine consecutive subjects...

超大视场头盔显示光学系统设计

An optical system for eyepieces was designed to meet the demand of a wide-angle head mounted display for the wide Field of View(FOV),high resolving power and compact,light-weight structure.Twelve groups of high quality eyepieces with a FOV of 33°×24° arraged in a 4×3 array were stitched in a single-eye optical system to realize the design with a wider FOV.The eyepiece was made up of a lens which contained a diffractive surface and an aspheric surface.The dispersion characteristics of binary optical elements were used to correct the chromatic aberration,and the aspheric surface was selected to correct the aberrations(spherical aberration,astigmatism,coma and distortion).Furthermore,an OLED micro-displayer was used to achieve compact and light-weight structure,and the field-of-viewing stitch was used to implement the wide field of view.Experiments show that obtained optical system can offer the horizontal FOV of 120° and the vertical FOV of 60°.Moreover,the resolving power is 43 pixel/degree,the MTF is higher than 0.1 at a spatial frequency of 30 lp/ mm across the entire visual field,and the maximum distortion is less than 3%.The optical system has perfect performance and can meet the domanial demands of virtual reality display and super-wide FOV.

Static and Transformative Images in Shakespeare's Dramatic Art

Phenomenology and ImagesAs early as 1794, Walter Whiter set out to explain how Shakespeare's images illuminate his plays by drawing on John Locke's then-novel theory of the association of ideas.1 Subsequent scholar, ranging from Edward Dowden and A. C. Bradley to Caroline Spurgeon, G. Wilson Knight, and Robert Heilman, stressed the importance of images to the formal, thematic, and affective power of Shakespeare's dramatic art.2 More recent scholarship has been no less concerned with the playwright's visual imagery, although scholars have increasingly focused on how Shakespeare's art explores the character of early modern visuality and the visual culture of the early modern era more generally.3 In the brief space of this essay, I examine Shakespeare's attention to the phenomenality of images: the way images are experienced perceptually and how they influence the perception of events. In keeping with the topic of this special issue on and Phenomenology, my particular aim is to show how Shakespeare's attention to images as phenomena can be illuminated by reading the plays dialogue with the work of modern phenomenologists such as Emmanuel Levinas, Maurice Merleau-Ponty, and Jean-Luc Marion.Phenomenology offers a particularly fruitful language through which to interrogate Shakespeare's attention to the complexity of our experience with images because images and visual perception are central to phenomenological inquiry. Examples of the key concepts the work of Levinas, Merleau-Ponty, and Marion include, respectively, the face-to-face encounter, the chiasm (or intertwining of visible and invisible), and the icon as a saturated phenomenon.4 Though phenomenology extends to the whole arena of embodied experience and all the senses, the prevalence of such concepts phenomenological thought points to the importance of vision and visibility to the tradition. The same can be said for Shakespeare, a literary artist writing for a form - dramatic theater - that is overtly visual. While acknowledging language as Shakespeare's medium, recent Shakespeare criticism has stressed that the visuality of the theater is central to its power.5 In what follows, I explore how phenomenology might illuminate our understanding of Shakespeare's images.ITo begin, consider Duke Theseus's musings on the relationship between apprehension and comprehension after hearing of the lovers' newfound concord A Midsummer Night's Dream:I never may believe theseAntique fables, nor these fairy toys.Lovers and madmen have such seething brains,Such fantasies, that apprehendMore than reason ever comprehends.Such tricks hath imagination,That if it would but apprehend some joy,It comprehends some bringer of that joy;Or the night, some fear,How easy is a bush supposed a bear!(5.1.2-6, 18-22)6Theseus offers this explanation order to dismiss strong imagination favor of cool reason, the faculty capable of discerning truth from illusion. According to Theseus, the Athenian lovers' sudden and collective change of heart after one the forest can only be a product of the shaping fantasies of strong imagination. For comparison, he offers the example of the bear and bush, both things (potentially present, given to perception) and images (known by their shape or figure). As things perceived as visual images, bear and bush produce (and are produced by) different cognitive responses: one runs from a bear out of fear (knowing it to be dangerous) but not a bush (even if its outline resembles a bear's). Theseus reveals that the conditions for apprehension (perception), as well as for comprehension (understanding), obtain the interaction between the entire sensible visual field and the particular observer's mind: an ostensibly present bush seen in the night is perceived as a presumably absent bear because the observer is imagining some fear. …

Visual Rotation Axis and Body Position Relative to the Gravitational Direction: Effects on Circular Vection

The visual–vestibular conflict theory asserts that visual–vestibular conflicts reduce vection and that vection strength is reduced with an increasing discrepancy between actual and expected vestibular activity. Most studies support this theory, although researchers have not always accepted them. To ascertain the conditions under which the theory of the visual–vestibular conflict can be applied, we measured circular vection strength accompanied by manipulation of the visual–otolith conflict by setting the axes of visual global motion (pitch, roll, and yaw) as either earth-horizontal or earth-vertical, using three different body positions (supine, left-lateral recumbent, and sitting upright). When the smaller stimulus was used, roll vection strength was greater with the visual–otolith conflict than without it, which contradicts the visual–vestibular conflict theory. We confirmed this result, as observers were able to distinguish circular vection from an illusory body tilt. Moreover, with observers in an upright position, the strength of yaw vection, which does not involve the visual–otolith conflict, increased and was almost equal to that of roll vection, which involves the visual–otolith conflict. This suggests that if the visual stimulus covers the entire visual field, the strength of circular vection around the earth-vertical axis exceeds that around the earth-horizontal axis, which is a finding consistent with the visual–vestibular conflict theory.

A Method to Measure and Predict Rates of Regional Visual Field Decay in Glaucoma

This study was conducted to measure the rate of visual field (VF) decay in glaucoma, to separate faster and slower components of decay, and to predict the rate of VF decay. Patients who had primary glaucoma and 6 or more years of follow-up were included. Thresholds at each VF location were regressed with linear, quadratic, and exponential models. The best model was used to parse the VF into slower and faster rate components. Two independent cohorts (glaucoma [n = 87] and cataract [n = 38]) were used to determine the technique's ability to distinguish areas of glaucomatous VF changes from those caused by cataract. VF forecasts, derived from the first half of follow-up, were compared with actual VF thresholds at the end of follow-up. The mean (±SD) years of follow-up and number of VFs for the main cohort (389 eyes of 309 patients) were 8.2 (±1.1) years and 15.7 (±3.0), respectively. The proportions of best fits were linear 2%, quadratic 1%, and exponential 97%. Proportions of eyes with exponential rates of decay ≥10% for the entire visual field (VF), faster components, and slower components were 20%, 56%, and 4%, respectively. The difference in decay rates between the faster and slower components was greater in the independent glaucoma cohort (19% ± 10%) than in the cataract cohort (5% ± 5%; P < 0.001). Test location forecasts significantly correlated with measured values (r(2) = 0.67; P < 0.001). This method isolates faster and slower components of VF decay in glaucoma, can identify patients who are fast progressors, and can predict patterns of future VF loss with appropriate confidence intervals. (ClinicalTrials.gov number, NCT00000148.).

Modeling long-range interactions across the visual field in stereo correspondence

AbstractWhen the eyes are converged, most objects in the visual scene will have a significant vertical disparity as measured at the retina. The pattern of vertical disparity across the retina is largely independent of object depth, depending mainly on the particular eye position adopted. Recently, Phillipson and Read (2010, European Journal of Neuroscience, doi:10.1111/j.1460-9568.2010.07454.x) showed that humans are better at achieving stereo correspondence when the vertical disparity field indicated infinite viewing distance, even when the physical viewing distance was just 30cm. They interpreted this as indicating that disparity encoding is optimized for long viewing distances, and is not updated to reflect changes in eye posture. Their results also indicated a significant effect of the visual periphery. Performance was better when the vertical disparity across the entire visual field was consistent with a given binocular eye position – even when this was not the eye position actually adopted – than when the vertical disparity beyond 20o eccentricity indicated a different eye position than that within 20o eccentricity. This is a surprising result, since (i) the task was to detect a target 8o in diameter, extending from 10o to 18o eccentricity, so information beyond 20o was completely irrelevant to the task, and (ii) many previous results indicate that the visual system detects and uses vertical disparity in local regions, even when the global vertical disparity field is not consistent with any single binocular eye position. Here, I show that this effect can be explained by a template-matching model in which the response of a population of disparity-detectors is compared with stored templates of the response expected to stimuli of known disparity.