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1.
PLoS One ; 15(8): e0238246, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32866203

RESUMO

Young children exhibit poorer visual performance than adults due to immaturity of the fovea and of the fundamental processing of visual functions such as masking and crowding. Recent studies suggest that masking and crowding are closely related to the size of the fundamental processing unit-the perceptive field (PF). However, while it is known that the retina and basic visual functions develop throughout childhood, it is not clear whether and how changes in the size of the PF affect masking and crowding. Furthermore, no retinal and perceptual development data have been collected from the same cohort and time. Here we explored the developmental process of the PF and the basic visual functions. Psychophysical and imaging methods were used to test visual functions and foveal changes in participants ranging from 3-17 years old. Lateral masking, crowding and contrast sensitivity were tested using computerized tasks. Foveal measurements were obtained from spectral-domain optical coherence tomography (OCT). The children patterns below 6 years exhibited high crowding, while the expected facilitation was found only at a larger target-flanker distance than required for children above 6 years, who exhibited the typical adult. Foveal thickness and macular volume for the children below 6 years were significantly lower than for the older group. Significant correlation was found for contrast sensitivity, foveal thickness and macular volume with age and between contrast sensitivity and foveal thickness. Our data suggest that the developmental processes at the retina and visual cortex occur in the same age range. Thus, in parallel to maturation of the PF, which enables reduction in crowding, foveal development contributes to increasing contrast sensitivity.


Assuntos
Retina/fisiologia , Acuidade Visual/fisiologia , Córtex Visual/fisiologia , Adolescente , Criança , Pré-Escolar , Sensibilidades de Contraste/fisiologia , Aglomeração , Feminino , Fóvea Central/fisiologia , Humanos , Edema Macular/fisiopatologia , Masculino , Tomografia de Coerência Óptica/métodos
2.
PLoS One ; 15(6): e0234151, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32520956

RESUMO

OBJECTIVES: To examine interocular asymmetry of foveal avascular zone (FAZ) and parafoveal capillary density metrics in sickle cell retinopathy (SCR) using optical coherence tomography angiography (OCT-A). METHODS: This cross-sectional, retrospective study evaluated SCR patients and unaffected controls who underwent 3x3mm macular OCT-A imaging using a spectral domain-OCT system. FAZ (area, perimeter, and acircularity index) and parafoveal capillary density metrics were computed for both eyes of each participant. In unaffected controls, interocular difference in FAZ and parafoveal capillary density metrics were evaluated using Bland-Altman plots. SCR patients with interocular difference outside the upper 97.5% and lower 2.5% limits of agreement from controls were defined as having interocular asymmetry. Area under receiver operating characteristic curve (AROC) was also performed to determine the ability of the absolute interocular difference to differentiate between subjects with SCR-including non-proliferative SCR (NP-SCR) and proliferative SCR (P-SCR)-and unaffected controls. RESULTS: Thirty-one patients with SCR (21 NP-SCR and 10 P-SCR) and 14 race-matched and age-matched controls were included for analysis. Interocular asymmetry was seen for all FAZ and parafoveal capillary density metrics in NP-SCR and P-SCR subjects. SCR subjects showed greater disease severity in the left-eye for FAZ and parafoveal capillary density metrics. CONCLUSIONS: NP-SCR and P-SCR patients demonstrated quantifiable interocular asymmetry in FAZ and parafoveal capillary density metrics compared to unaffected subjects, with left-eye predominance in disease severity.


Assuntos
Anemia Falciforme/patologia , Capilares/fisiologia , Fóvea Central/fisiologia , Doenças Retinianas/patologia , Adulto , Anemia Falciforme/complicações , Área Sob a Curva , Estudos de Casos e Controles , Estudos Transversais , Olho/diagnóstico por imagem , Feminino , Fóvea Central/irrigação sanguínea , Humanos , Masculino , Pessoa de Meia-Idade , Curva ROC , Doenças Retinianas/etiologia , Estudos Retrospectivos , Índice de Gravidade de Doença , Tomografia de Coerência Óptica , Adulto Jovem
3.
Invest Ophthalmol Vis Sci ; 61(5): 23, 2020 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-32413126

RESUMO

Purpose: Grouping of flankers from the target can modulate crowding in adults. Visual acuity in children is measured clinically using charts with targets and different flankers to enhance spatial interactions. We investigated grouping effects on interactions using visual acuity letters, flanked by contours and letters, in children. Methods: Visual acuity for isolated and flanked letters was measured in 155 three- to 11-year old children and 32 adults. Flankers were one stroke width from the target and were a box or four bars and black or red letters. Magnitudes of interaction were flanked minus isolated logMAR acuities. Psychometric function slopes were also examined. Results: Magnitudes of interaction by contours did not change significantly with age. They were 0.047 ± 0.014 logMAR more with bars than a box. Interaction from flanking letters reduced with age, adults being not different from 9- to 11-year-olds for black and red letter surrounds. It was weaker by 0.033 ± 0.013 logMAR when a black letter was surrounded by red rather than black letters. Psychometric function slopes for visual acuity were steepest for the youngest children (3-5 years). Conclusions: For contour and letter flankers, grouping effects on interaction magnitude are age independent. Grouping bars into a box forming a single object reduces magnitude of effect. Grouping letter flankers by color and ungrouping them from the target reduce interaction magnitude by ∼8%, suggesting that luminance-defined form dominates. Differently colored letter flankers of high-luminance contrast on acuity charts could draw attention to the target but retain significant interaction strength.


Assuntos
Fóvea Central/fisiologia , Processamento Espacial/fisiologia , Acuidade Visual/fisiologia , Adolescente , Criança , Pré-Escolar , Sensibilidades de Contraste/fisiologia , Aglomeração , Feminino , Percepção de Forma/fisiologia , Humanos , Masculino , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa , Psicometria
4.
Proc Natl Acad Sci U S A ; 117(20): 11178-11183, 2020 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-32358186

RESUMO

It is known that attention shifts prior to a saccade to start processing the saccade target before it lands in the foveola, the high-resolution region of the retina. Yet, once the target is foveated, microsaccades, tiny saccades maintaining the fixated object within the fovea, continue to occur. What is the link between these eye movements and attention? There is growing evidence that these eye movements are associated with covert shifts of attention in the visual periphery, when the attended stimuli are presented far from the center of gaze. Yet, microsaccades are primarily used to explore complex foveal stimuli and to optimize fine spatial vision in the foveola, suggesting that the influences of microsaccades on attention may predominantly impact vision at this scale. To address this question we tracked gaze position with high precision and briefly presented high-acuity stimuli at predefined foveal locations right before microsaccade execution. Our results show that visual discrimination changes prior to microsaccade onset. An enhancement occurs at the microsaccade target location. This modulation is highly selective and it is coupled with a drastic impairment at the opposite foveal location, just a few arcminutes away. This effect is strongest when stimuli are presented closer to the eye movement onset time. These findings reveal that the link between attention and microsaccades is deeper than previously thought, exerting its strongest effects within the foveola. As a result, during fixation, foveal vision is constantly being reshaped both in space and in time with the occurrence of microsaccades.


Assuntos
Atenção/fisiologia , Movimentos Oculares/fisiologia , Fóvea Central/fisiologia , Movimentos Sacádicos/fisiologia , Visão Ocular/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Estimulação Luminosa , Percepção Visual , Adulto Jovem
5.
J Exp Psychol Hum Percept Perform ; 46(3): 292-312, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32077743

RESUMO

At normal interpersonal distances all features of a face cannot fall within one's fovea simultaneously. Given that certain facial features are differentially informative of different emotions, does the ability to identify facially expressed emotions vary according to the feature fixated and do saccades preferentially seek diagnostic features? Previous findings are equivocal. We presented faces for a brief time, insufficient for a saccade, at a spatial position that guaranteed that a given feature-an eye, cheek, the central brow, or mouth-fell at the fovea. Across 2 experiments, observers were more accurate and faster at discriminating angry expressions when the high spatial-frequency information of the brow was projected to their fovea than when 1 or other cheek or eye was. Performance in classifying fear and happiness (Experiment 1) was not influenced by whether the most informative features (eyes and mouth, respectively) were projected foveally or extrafoveally. Observers more accurately distinguished between fearful and surprised expressions (Experiment 2) when the mouth was projected to the fovea. Reflexive first saccades tended toward the left and center of the face rather than preferentially targeting emotion-distinguishing features. These results reflect the integration of task-relevant information across the face constrained by the differences between foveal and extrafoveal processing (Peterson & Eckstein, 2012). (PsycINFO Database Record (c) 2020 APA, all rights reserved).


Assuntos
Emoções , Movimentos Oculares/fisiologia , Expressão Facial , Reconhecimento Facial/fisiologia , Percepção Social , Adulto , Feminino , Fixação Ocular/fisiologia , Fóvea Central/fisiologia , Humanos , Masculino , Adulto Jovem
6.
PLoS One ; 15(1): e0219725, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31999697

RESUMO

Evidence from neuroimaging and brain stimulation studies suggest that visual information about objects in the periphery is fed back to foveal retinotopic cortex in a separate representation that is essential for peripheral perception. The characteristics of this phenomenon have important theoretical implications for the role fovea-specific feedback might play in perception. In this work, we employed a recently developed behavioral paradigm to explore whether late disruption to central visual space impaired perception of color. In the first experiment, participants performed a shape discrimination task on colored novel objects in the periphery while fixating centrally. Consistent with the results from previous work, a visual distractor presented at fixation ~100ms after presentation of the peripheral stimuli impaired sensitivity to differences in peripheral shapes more than a visual distractor presented at other stimulus onset asynchronies. In a second experiment, participants performed a color discrimination task on the same colored objects. In a third experiment, we further tested for this foveal distractor effect with stimuli restricted to a low-level feature by using homogenous color patches. These two latter experiments resulted in a similar pattern of behavior: a central distractor presented at the critical stimulus onset asynchrony impaired sensitivity to peripheral color differences, but, importantly, the magnitude of the effect was stronger when peripheral objects contained complex shape information. These results show a behavioral effect consistent with disrupting feedback to the fovea, in line with the foveal feedback suggested by previous neuroimaging studies.


Assuntos
Percepção de Cores/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Campos Visuais/fisiologia , Adolescente , Adulto , Atenção/fisiologia , Cor , Retroalimentação Fisiológica , Feminino , Fóvea Central/fisiologia , Humanos , Masculino , Estimulação Luminosa , Córtex Visual/fisiologia
7.
Psychol Res ; 84(1): 231-244, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29387939

RESUMO

Object perception across saccadic eye movements is assumed to result from integrating two information sources: incoming peripheral object information and information from a foveal prediction (Herwig and Schneider, J Exp Psychol Gen 143(5):1903-1922, 2014, Herwig, J Vis 15(16), 7, 2015). Predictions are supposed to be based on transsaccadic associations of peripheral and foveal object information. The main function of these predictions may be to conceal discrepancies in resolution and locations across saccades. Here we ask how predictions are affected by discrepancies between peripheral and foveal objects. Participants learned unfamiliar transsaccadic associations by making saccades to objects whose shape systematically changed during the saccade. Importantly, we manipulated the size of this change between participants to induce different magnitudes of object discrepancy. In a subsequent test, we found that judgment shifts of peripheral shape perception toward the predicted foveal input depended on change size during acquisition. Specifically, the contribution of prediction decreased for large changes but did not reach zero, showing that even for large changes (i.e., square to circle or vice versa) the prediction was not ignored completely. These findings indicate that object discrepancy during learning determines how much the resulting foveal prediction contributes to perception in the periphery.


Assuntos
Movimentos Oculares/fisiologia , Fóvea Central/fisiologia , Julgamento/fisiologia , Aprendizagem/fisiologia , Estimulação Luminosa , Movimentos Sacádicos/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
8.
J Glaucoma ; 29(2): 104-111, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31764579

RESUMO

PURPOSE: To investigate the hypothesis that macular structure, function, and vessel density (VD) measurements can predict foveal threshold (FT) outcomes in glaucomatous eyes. MATERIALS AND METHODS: One hundred ninety-five eyes from 195 subjects (134 subjects with early-to-moderate stage open-angle glaucoma and 61 healthy controls) who underwent optical coherence tomography angiography imaging and 24-2 visual field (VF) testing with FT measurements on the same day were retrospectively enrolled in this study. The association of FT with macular structural/functional/VD measurements was evaluated using partial correlation analyses with adjustment for age and linear regression analyses. RESULTS: FT showed significant correlations between the thickness of the macular ganglion cell-inner plexiform layer (mGCIPL) (r=0.330, P<0.001) and the mean sensitivity (MS) of the central 5 and 10 degrees VF points (r=0.448, P<0.001 and r=0.361, P<0.001). Significant correlations were also found between FT and VD measurements at the inferior and superior parafoveal sectors (r=0.455, P<0.001 and r=0.438, P<0.001). In multivariate linear regression analyses controlling the covariates, the thickness of the mGCIPL, central 5 degrees VF MS, and parafoveal VD were significantly associated with FT (all P<0.001). There was also a significant association between FT and logMAR best-corrected visual acuity (ß=-5.647, P<0.001). CONCLUSIONS: Macular VD along with mGCIPL thickness and central 5 degrees VF MS independently predict FT outcomes even in the eyes of patients with early-to-moderate stage open-angle glaucoma.


Assuntos
Fóvea Central/fisiologia , Glaucoma de Ângulo Aberto/fisiopatologia , Macula Lutea/fisiopatologia , Vasos Retinianos/patologia , Adulto , Idoso , Estudos Transversais , Feminino , Angiofluoresceinografia , Humanos , Pressão Intraocular/fisiologia , Masculino , Pessoa de Meia-Idade , Fibras Nervosas/patologia , Células Ganglionares da Retina/patologia , Estudos Retrospectivos , Limiar Sensorial/fisiologia , Tomografia de Coerência Óptica/métodos , Testes de Campo Visual , Campos Visuais/fisiologia
9.
Atten Percept Psychophys ; 82(2): 585-592, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31820280

RESUMO

Some types of object features, such as color, shape, or location, can be processed separately within the visual system, requiring that they be correctly "bound" to a single object via attentional selection of a subset of visual information. Forcing selection to spread too widely can cause an illusion where these features misbind to objects, creating illusory objects that were never present. Here, we present a novel display that produces a robust color-location misbinding illusion that we call foveal gravity (viewable at https://osf.io/2bndg/). When observers selected only a set of colored objects, colors were largely perceived in their correct locations. When observers additionally selected objects in the far periphery, colors in the near periphery migrated closer to the fovea on over 35% of trials. We speculate that foveal gravity occurs because locations closer to the fovea are more likely to defeat more peripheral locations in competitive interactions to "win" the task-relevant color.


Assuntos
Percepção de Cores/fisiologia , Fóvea Central/fisiologia , Ilusões Ópticas/fisiologia , Estimulação Luminosa/métodos , Adolescente , Adulto , Atenção/fisiologia , Feminino , Humanos , Masculino , Adulto Jovem
10.
J Vis ; 19(14): 26, 2019 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-31880782

RESUMO

What we see is influenced by where we look. When confronted with multiple relevant targets, inaccurate saccade target selection can impair perceptual performance. Here we ask whether endpoint selection can be optimized by the mechanism maintaining saccade accuracy: saccade adaptation. Therefore, we introduce a double-target adaptation task, where a presaccadic peripheral stimulus (plaid) splits vertically into its two components (Gabor patches) during horizontal saccades. While both targets were task-relevant, one of them provided more information for the perceptual task, because it could only be identified after the saccade with near-foveal vision. The other target was highly salient and could also be identified in the presaccadic plaid using peripheral vision. This double-target paradigm induced saccade adaptation: Without a perceptual task, participants adapted to the salient target. When both targets were judged sequentially, participants mostly adapted to the target they had to judge first. When targets were judged simultaneously, endpoints were biased toward the informative target but showed no gradual learning and fell short of optimality. We observed gradual adaptation when targets shifted randomly such that a strategic adjustment of endpoints was not possible. Overall, these findings show that when multiple targets compete, our oculomotor system can learn to adjust endpoints in order to maximize information for perception. Yet individual variability and other factors affecting target priority play a crucial role.


Assuntos
Adaptação Fisiológica , Movimentos Sacádicos , Percepção Espacial , Percepção Visual , Adolescente , Adulto , Feminino , Fóvea Central/fisiologia , Humanos , Masculino , Estimulação Luminosa , Probabilidade , Campos Visuais , Adulto Jovem
11.
J Vis ; 19(12): 18, 2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31627211

RESUMO

The human eye changes focus-accommodates-to minimize blur in the retinal image. Previous work has shown that stimulation of nonfoveal retina can produce accommodative responses when no competing stimulus is presented to the fovea. In everyday situations it is very common for the fovea and other parts of the retina to be stimulated simultaneously. We examined this situation by asking how nonfoveal retina contributes to accommodation when the fovea is also stimulated. There were three experimental conditions. (a) Real change in which stimuli of different sizes, centered on the fovea, were presented at different optical distances. Accommodation was, as expected, robust because there was no conflicting stimulation of other parts of the retina. (b) Simulated change, no conflict in which stimuli of different sizes, again centered on the fovea, were presented at different simulated distances using rendered chromatic blur. Accommodation was robust in this condition because there was no conflict between the central and peripheral stimuli. (c) Simulated change, conflict in which a central disk (of different diameters) was presented along with an abutting peripheral annulus. The disk and annulus underwent opposite changes in simulated distance. Here we observed a surprisingly consistent effect of the peripheral annulus. For example, when the diameter of the central stimulus was 8° (thereby stimulating the fovea and parafovea), the abutting peripheral annulus had a significant effect on accommodation. We discuss how these results may help us understand other situations in which nonfixated targets affect the ability to focus on a fixated target. We also discuss potential implications for the development of myopia and for foveated rendering.


Assuntos
Acomodação Ocular , Fóvea Central/fisiologia , Miopia/fisiopatologia , Retina/fisiologia , Adolescente , Adulto , Cor , Face , Feminino , Humanos , Masculino , Adulto Jovem
12.
J Vis ; 19(12): 21, 2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31647515

RESUMO

Depth perception requires the use of an internal model of the eye-head geometry to infer distance from binocular retinal images and extraretinal 3D eye-head information, particularly ocular vergence. Similarly, for motion in depth perception, gaze angle is required to correctly interpret the spatial direction of motion from retinal images; however, it is unknown whether the brain can make adequate use of extraretinal version and vergence information to correctly transform binocular retinal motion into 3D spatial coordinates. Here we tested this hypothesis by asking participants to reconstruct the spatial trajectory of an isolated disparity stimulus moving in depth either peri-foveally or peripherally while participants' gaze was oriented at different vergence and version angles. We found large systematic errors in the perceived motion trajectory that reflected an intermediate reference frame between a purely retinal interpretation of binocular retinal motion (not accounting for veridical vergence and version) and the spatially correct motion. We quantify these errors with a 3D reference frame model accounting for target, eye, and head position upon motion percept encoding. This model could capture the behavior well, revealing that participants tended to underestimate their version by up to 17%, overestimate their vergence by up to 22%, and underestimate the overall change in retinal disparity by up to 64%, and that the use of extraretinal information depended on retinal eccentricity. Since such large perceptual errors are not observed in everyday viewing, we suggest that both monocular retinal cues and binocular extraretinal signals are required for accurate real-world motion in depth perception.


Assuntos
Percepção de Profundidade , Movimentos Oculares , Percepção de Movimento , Retina/fisiologia , Disparidade Visual , Sinais (Psicologia) , Desenho de Equipamento , Feminino , Fóvea Central/fisiologia , Humanos , Imageamento Tridimensional , Masculino , Reprodutibilidade dos Testes , Visão Binocular , Adulto Jovem
13.
J Vis ; 19(11): 2, 2019 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-31480073

RESUMO

Research has shown that participants can extract the average facial expression from a set of faces when these were presented at fixation. In this study, we investigated whether this performance would be modulated by eccentricity given that neural resources are limited outside the foveal region. We also examined whether or not there would be compulsory averaging in the parafovea as has been previously reported for the orientation of Gabor patches by Parkes, Lund, Angelucci, Solomon, and Morgan (2001). Participants were presented with expressive faces (alone or in sets of nine, at fixation or at 3° to the left or right) and were asked to identify the expression of the central target face or to estimate the average expression of the set. Our results revealed that, although participants were able to extract average facial expressions in central and parafoveal conditions, their performance was superior in the parafovea, suggesting facilitated averaging outside the fovea by peripheral mechanisms. Furthermore, regardless of whether the task was to judge the expression of the central target or set average, participants had a tendency to identify central targets' expressions in the fovea but were compelled to average in the parafovea, a finding consistent with compulsory averaging. The data also supported averaging over substitution models of crowding. We conclude that the ability to extract average expressions in sets of faces and identify single targets' facial expressions is influenced by eccentricity.


Assuntos
Expressão Facial , Reconhecimento Facial/fisiologia , Adulto , Análise de Variância , Emoções/fisiologia , Feminino , Fixação Ocular/fisiologia , Fóvea Central/fisiologia , Humanos , Masculino , Modelos Biológicos , Orientação/fisiologia , Adulto Jovem
14.
J Vis ; 19(11): 3, 2019 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-31480075

RESUMO

Stereopsis is important for tasks of daily living such as eye-hand coordination. It is best in central vision but is also mediated by the periphery. Previously we have shown that individuals with central-field loss who have residual stereopsis in the periphery perform better at an eye-hand-coordination task when they perform the task binocularly rather than monocularly. Here we seek to determine what sets the limit of stereopsis, defined as the largest disparity that supports the sustained appearance of depth, in the near periphery in healthy individuals. While stereoacuity thresholds increase sharply with eccentricity, Panum's area increases much more slowly. We used a rigorous method to determine the uppermost limit of disparity. At long durations, the two half-images that define a large disparity appear as two isolated targets in the same flat plane; small incremental changes in disparity produce changes in the separation between the half-images, and disparity magnitude can be judged on the basis of separation, like a monocular width judgment. The disparity limit is the point at which the threshold for judging dichoptic separation between the half-images is equal to the monocular width-discrimination threshold. The disparity limit at 10° was a factor of 2-4 times larger than the fovea, regardless of the meridian tested. The increase in the disparity limit with eccentricity was shallow, similar to that of Panum's area. Within this disparity limit, disparity increment thresholds were comparable for foveal and peripheral targets, illustrating the significance and utility of peripheral stereopsis, especially in the absence of foveal stereopsis.


Assuntos
Percepção de Profundidade/fisiologia , Disparidade Visual/fisiologia , Visão Ocular/fisiologia , Fixação Ocular/fisiologia , Fóvea Central/fisiologia , Humanos , Estimulação Luminosa , Desempenho Psicomotor/fisiologia , Visão Binocular/fisiologia , Acuidade Visual/fisiologia
15.
J. optom. (Internet) ; 12(3): 180-185, jul.-sept. 2019. tab, graf
Artigo em Inglês | IBECS | ID: ibc-185368

RESUMO

Purpose: To compare the retinal sensitivity and evaluate its contribution to the foveal sensitivity in patients with and without diabetes who maintain normal visual acuity. Methods: Observational, descriptive, cross-sectional and prospective study in 20 subjects without diabetes (group 1) and 23 with type 2 diabetes mellitus (group 2) that had no ocular abnormalities. Retinal sensitivity was measured with the macular threshold test by the Humphrey's computerized perimeter. The mean sensitivity in each of the 16 points and the foveal sensitivity were compared between groups using the Mann-Whitney's U test; the correlation between retinal sensitivity and foveal sensitivity was analyzed by the Spearman's test and the contribution of each point to the foveal sensitivity was identified by multiple regression. Results: Sixty eyes were evaluated, 30 in group 1 and 30 in group 2; the mean foveal sensitivity was 34.77 ± 0.5dB in group 1 and 32.87 ± 0.6 in group 2. The highest sensitivity of the temporal visual field had an inferior paracentral location (point 3) in both groups. In the linear regression analysis, points which contributed to the foveal sensitivity were 1 in group 1 and points 7 and 15 in group 2. Conclusions: Subjects without diabetes have a significantly higher sensitivity in the temporal retina compared with those with diabetes; points with highest mean retinal sensitivity do not correspond to the central four. The reduced sensitivity in point 1 decreases the mean foveal sensitivity in subjects with diabetes, because this variable correlates with lower perimetry points


Objetivo: Comparar la sensibilidad de la retina y evaluar su contribución a la sensibilidad de la fóvea en pacientes con y sin diabetes con agudeza visual normal. Métodos: Estudio observacional, descriptivo, transversal y prospectivo en 20 sujetos no diabéticos (grupo 1) y 23 con diabetes mellitus tipo 2 (grupo 2) sin anomalías oculares. La sensibilidad de la retina se midió mediante la prueba de cuantificación del umbral macular realizada con campimetría computarizada Humphrey. La sensibilidad media en cada uno de los 16 puntos y la sensibilidad de la fóvea se compararon entre grupos mediante la prueba U de Mann Whitney; la correlación entre la sensibilidad de la retina y la sensibilidad de la fóvea se analizó mediante la prueba de Spearman, y la contribución de cada punto a la sensibilidad de la fóvea se identificó mediante regresión múltiple. Resultados: Se evaluaron sesenta ojos: 30 en el grupo 1, y 30 en el grupo 2; la media de la sensibilidad de la fóvea fue de 34,77 ± 0,5 dB en el grupo 1, y de 32,87 ± 0,6 en el grupo 2. La mayor sensibilidad del campo visual temporal tuvo una localización paracentral inferior (punto 3) en ambos grupos. En el análisis de regresión lineal, los puntos que contribuyeron a la sensibilidad de la fóvea fueron el punto 1 en el grupo 1, y los puntos 7 y 15 en el grupo 2. Conclusiones: Los sujetos no diabéticos tienen una sensibilidad significativamente mayor en la retina temporal en comparación a los sujetos diabéticos; los puntos con mayor sensibilidad media de la retina no corresponden a los cuatro centrales. La sensibilidad reducida en el punto 1 disminuye la sensibilidad de la fóvea en sujetos diabéticos, ya que esta variable guarda relación con los puntos perimétricos inferiores


Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Diabetes Mellitus Tipo 2/fisiopatologia , Retinopatia Diabética/fisiopatologia , Fóvea Central/fisiologia , Macula Lutea/fisiopatologia , Acuidade Visual/fisiologia , Campos Visuais/fisiologia , Estudos Transversais , Estudos Prospectivos , Análise de Regressão
16.
Invest Ophthalmol Vis Sci ; 60(10): 3456-3467, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31398255

RESUMO

Purpose: To describe foveal sparing (FS) in central retinal dystrophies (RD). Methods: Participants for this retrospective study were identified from the retinal dystrophy database of the Department of Ophthalmology at Radboud University Medical Center. FS was defined as an intact foveal structure surrounded by at least 180° of chorioretinal atrophy, and a best-corrected visual acuity (BCVA) of <1.0 logMAR (>20/200 Snellen). Eligible eyes were identified using fundus autofluorescence (FAF) images, and FS was confirmed using near-infrared reflectance (NIR) imaging and spectral-domain optical coherence tomography when available. Clinical and demographic data were extracted from medical records. We performed quantification of FS and chorioretinal atrophic areas using semiautomated software on fundus autofluorescence and NIR images. We calculated the chronologic change using eye-wise linear regression. Results: We identified 36 patients (56 eyes) with FS. RDs included: Stargardt disease (STGD1;20 patients), central areolar choroidal dystrophy (CACD; 7 patients), mitochondrial retinal dystrophy (MRD; 6 patients), pseudo-Stargardt pattern dystrophy (PSPD; 3 patients). Median age at first presentation was 60 (interquartile range [IQR] 54-63) years. Median BCVA at first presentation ranged from 20/25 Snellen in STGD1, to 20/38 Snellen in MRD. Progression of the chorioretinal atrophic area ranged from 0.26 (0.25-0.28) mm/year in PSPD, to 0.14 (0.11-0.22) in CACD. Change in FS area over time was similar between the different dystrophies. Conclusions: The presence of FS in different RDs suggests a disease-independent mechanism that prolongs the survival of the fovea. The associated preservation of BCVA is important for the individual prognosis and has implications for the design of therapeutic trials for RDs.


Assuntos
Fóvea Central/fisiologia , Distrofias Retinianas/diagnóstico , Progressão da Doença , Eletrorretinografia , Feminino , Angiofluoresceinografia/métodos , Fóvea Central/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-Idade , Distrofias Retinianas/fisiopatologia , Estudos Retrospectivos , Tomografia de Coerência Óptica/métodos , Acuidade Visual/fisiologia
17.
J Vis ; 19(9): 1, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31369042

RESUMO

Behavioral studies in humans indicate that peripheral vision can do object recognition to some extent. Moreover, recent studies have shown that some information from brain regions retinotopic to visual periphery is somehow fed back to regions retinotopic to the fovea and disrupting this feedback impairs object recognition in human. However, it is unclear to what extent the information in visual periphery contributes to human object categorization. Here, we designed two series of rapid object categorization tasks to first investigate the performance of human peripheral vision in categorizing natural object images at different eccentricities and abstraction levels (superordinate, basic, and subordinate). Then, using a delayed foveal noise mask, we studied how modulating the foveal representation impacts peripheral object categorization at any of the abstraction levels. We found that peripheral vision can quickly and accurately accomplish superordinate categorization, while its performance in finer categorization levels dramatically drops as the object presents further in the periphery. Also, we found that a 300-ms delayed foveal noise mask can significantly disturb categorization performance in basic and subordinate levels, while it has no effect on the superordinate level. Our results suggest that human peripheral vision can easily process objects at high abstraction levels, and the information is fed back to foveal vision to prime foveal cortex for finer categorizations when a saccade is made toward the target object.


Assuntos
Percepção de Forma/fisiologia , Fóvea Central/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Campos Visuais/fisiologia , Adulto , Discriminação Psicológica , Feminino , Humanos , Masculino
18.
Proc Natl Acad Sci U S A ; 116(36): 17729-17734, 2019 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-31427541

RESUMO

The approximate number system (ANS) has attracted broad interest due to its potential importance in early mathematical development and the fact that it is conserved across species. Models of the ANS and behavioral measures of ANS acuity both assume that quantity estimation is computed rapidly and in parallel across an entire view of the visual scene. We present evidence instead that ANS estimates are largely the product of a serial accumulation mechanism operating across visual fixations. We used an eye-tracker to collect data on participants' visual fixations while they performed quantity-estimation and -discrimination tasks. We were able to predict participants' numerical estimates using their visual fixation data: As the number of dots fixated increased, mean estimates also increased, and estimation error decreased. A detailed model-based analysis shows that fixated dots contribute twice as much as peripheral dots to estimated quantities; people do not "double count" multiply fixated dots; and they do not adjust for the proportion of area in the scene that they have fixated. The accumulation mechanism we propose explains reported effects of display time on estimation and earlier findings of a bias to underestimate quantities.


Assuntos
Movimentos Oculares/fisiologia , Fóvea Central/fisiologia , Modelos Neurológicos , Visão Ocular/fisiologia , Feminino , Humanos , Masculino , Matemática
19.
J Vis ; 19(9): 8, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31426086

RESUMO

There is a large literature on lateral effects in pattern vision but no consensus about them or comprehensive model of them. This paper reviews the literature with a focus on the effects of parallel context in the central fovea. It describes seven experiments that measure detection and discrimination thresholds in annular and Gabor-pattern contexts at different separations. It presents a model of these effects, which is an elaboration of Foley's (1994) model. The model describes the results well, and it shows that lateral context affects the response to the target by both multiplicative excitation and additive inhibition. Both lateral effects extend for several wavelengths beyond the target. They vary in relative strength, producing near suppression and far enhancement of the response to the target. The model describes the detection and discrimination results well, and it also describes the results of experiments on lateral effects on perceived contrast. The model is consistent with the physiology of V1 cells.


Assuntos
Sensibilidades de Contraste/fisiologia , Fóvea Central/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Discriminação Psicológica/fisiologia , Humanos , Limiar Sensorial/fisiologia
20.
Curr Biol ; 29(13): 2109-2119.e7, 2019 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-31257138

RESUMO

A defining feature of the primate visual system is its foveated nature. Processing of foveal retinal input is important not only for high-quality visual scene analysis but also for ensuring precise, albeit tiny, gaze shifts during high-acuity visual tasks. The representations of foveal retinal input in the primate lateral geniculate nucleus and early visual cortices have been characterized. However, how such representations translate into precise eye movements remains unclear. Here, we document functional and structural properties of the foveal visual representation of the midbrain superior colliculus. We show that the superior colliculus, classically associated with extra-foveal spatial representations needed for gaze shifts, is highly sensitive to visual input impinging on the fovea. The superior colliculus also represents such input in an orderly and very specific manner, and it magnifies the representation of foveal images in neural tissue as much as the primary visual cortex does. The primate superior colliculus contains a high-fidelity visual representation, with large foveal magnification, perfectly suited for active visuomotor control and perception.


Assuntos
Fóvea Central/fisiologia , Macaca mulatta/fisiologia , Colículos Superiores/fisiologia , Percepção Visual/fisiologia , Animais , Movimentos Oculares , Masculino
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