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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(5): e0233295, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32428008

RESUMO

PURPOSE: Epiphora causes deterioration in contrast sensitivity in some eye diseases. This study was conducted to investigate contrast sensitivity in eyes with epiphora caused by lacrimal passage obstruction. METHODS: This single-center, prospective case series enrolled 57 patients with unilateral lacrimal passage obstruction. The best-corrected visual acuity (BCVA), contrast sensitivity function, and lower tear meniscus of the affected and contralateral unaffected eyes were compared. The area under the log contrast sensitivity function (AULCSF) was calculated. RESULTS: The BCVA did not significantly differ between the affected and contralateral eyes, while the AULCSF was significantly lower in the affected eyes than that in the contralateral eyes (median 1.35, interquartile range 1.22-1.44 vs. median 1.36, interquartile range 1.28-1.46, P = 0.032). Lower tear meniscus parameters were significantly higher in the affected eyes than those in the contralateral eyes (P < 0.005). CONCLUSIONS: The contrast sensitivity function is significantly diminished in eyes with epiphora caused by lacrimal passage obstruction.


Assuntos
Sensibilidades de Contraste/fisiologia , Doenças do Aparelho Lacrimal/fisiopatologia , Acuidade Visual/fisiologia , Idoso , Estudos de Casos e Controles , Feminino , Humanos , Aparelho Lacrimal/fisiologia , Doenças do Aparelho Lacrimal/metabolismo , Obstrução dos Ductos Lacrimais/fisiopatologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Lágrimas , Acuidade Visual/efeitos dos fármacos
3.
PLoS One ; 15(5): e0233786, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32469998

RESUMO

A single experiment required 40 younger and older adults to discriminate global shape as depicted by Glass patterns (concentric and radial organizations). Such patterns have been widely used for decades, because in order to successfully perceive the depicted shape, the visual system has to detect both locally oriented features (dipoles) and their alignments across extended regions of space. In the current study, we manipulated the number of constituent dipoles in the stimulus patterns (40 or 200), the noise-to-signal ratio (zero, 1.0, & 5.0), and the pattern size (6.0 & 25.0 degrees visual angle). The observers' shape discrimination accuracies (d' values) decreased markedly as the amount of noise increased, and there were smaller (but significant) effects of both overall pattern size and the number of stimulus dipoles. Interestingly, while there was a significant effect of age, it was relatively small: the overall d' values for older and younger adults were 2.07 and 2.34, respectively. Older adults therefore retain an effective ability to visually perceive global shape, even for sparsely-defined patterns embedded in noise.


Assuntos
Envelhecimento Cognitivo/fisiologia , Sensibilidades de Contraste/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Aprendizagem por Discriminação , Percepção de Distância/fisiologia , Humanos , Pessoa de Meia-Idade , Orientação/fisiologia , Adulto Jovem
4.
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
5.
Curr Opin Ophthalmol ; 31(4): 225-233, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32398417

RESUMO

PURPOSE OF REVIEW: This review outlines ophthalmic diagnostic systems, which objectively evaluates the human visual system and its potential beyond that of Snellen acuity. RECENT FINDINGS: Advances in ophthalmic diagnostic systems have allowed for a deeper understanding of the optical principles of the human eye and have created the opportunity to evolve our current standards of vision assessment beyond Snellen acuity charts. Definitive comparative and validation trials will continue to be necessary in order for these advanced diagnostics to gain more widespread acceptance in the specialty, in addition to providing the guidance on the specific indications and utilities. SUMMARY: Advancements in wavefront analysis, light scatter measurements, and adaptive optics technologies can provide greater insight into an individual optical system's potential and irregularities. Modalities that test for anterior corneal surface and whole eye aberrations, light scatter and contrast sensitivity can be an excellent educational tool for our patients to help them better understand their visual dysfunction and can prove useful for medical or surgical decision-making.


Assuntos
Sensibilidades de Contraste/fisiologia , Córnea/fisiologia , Refração Ocular/fisiologia , Aberrações de Frente de Onda da Córnea/fisiopatologia , Humanos , Luz , Espalhamento de Radiação , Testes Visuais , Acuidade Visual/fisiologia
6.
J Vis ; 20(3): 2, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32181858

RESUMO

A metacontrast masking paradigm was employed to provide evidence for the richness and diversity of our visual experience. Square- and diamond-shaped targets were followed by square- and diamond-shaped masks at varying stimulus onset asynchronies (SOAs), resulting in shape-congruent and shape-incongruent trials. In Experiment 1, participants reported in each trial how they perceived target and mask. After extended training, seven different aspects of the target could be distinguished as specific percepts in this metacontrast masking paradigm. These percepts encompass aspects including the temporal distance between both stimuli, the perceived contrast of the target, and motion percepts resulting from the interplay between the target and mask. Participants spontaneously reported each of these percepts, and the frequency of reports varied systematically with SOA and the congruency between target and mask. In Experiment 2, we trained a new group of participants to distinguish each of these target percepts. Again, the frequency of reports of the specific percepts varied with SOA and congruency, just as in Experiment 1. In a last session, we measured objective discrimination performance yielding the typical individually different masking functions across SOAs. An examination of the relation between the frequencies of reports of subjective percepts and objective discrimination performance revealed multiple dissociations between these measures. Results suggest a multidimensional pattern of subjective experiences under metacontrast, which is reflected in dissociated subjective and objective measures of visual awareness. As a consequence, awareness cannot be assessed exhaustively by a single measure, thus challenging the use of simple one-dimensional subjective or objective measures in visual masking.


Assuntos
Sensibilidades de Contraste/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Mascaramento Perceptivo/fisiologia , Adulto , Feminino , Humanos , Individualidade , Masculino , Adulto Jovem
7.
J Vis ; 20(3): 5, 2020 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-32196068

RESUMO

Previous electroencephalographic research on attentional salience did not fully capture the complexities of low-level vision, which relies on both cone-opponent chromatic and cone-additive luminance mechanisms. We systematically varied color and luminance contrast using a visual search task for a higher contrast target to assess the degree to which the salience-computing attentional mechanisms are constrained by low-level visual inputs. In our first experiment, stimuli were defined by contrast that isolated chromatic or luminance mechanisms. In our second experiment, targets were defined by contrasts that isolated or combined achromatic and chromatic mechanisms. In both experiments, event-related potential waveforms contralateral and ipsilateral to the target were qualitatively different for chromatic- compared to luminance-defined stimuli. The same was true of the difference waves computed from these waveforms, with isoluminant stimuli eliciting a mid-latency posterior contralateral negativity (PCN) component and achromatic stimuli eliciting a complex of multiple components, including an early posterior contralateral positivity followed by a late-latency PCN. Combining color with luminance resulted in waveform and difference wave patterns equivalent to those of achromatic stimuli. When large levels of chromaticity contrast were added to targets with small levels of luminance contrast, PCN latency was speeded. In conclusion, the mechanisms underlying attentional salience are constrained by the low-level inputs they receive. Furthermore, speeded PCN latencies for stimuli that combine color and luminance signals compared to stimuli that contain luminance alone demonstrate that color and luminance channels are integrated during pre-attentive visual processing, before top-down allocation of attention is triggered.


Assuntos
Adaptação Ocular/fisiologia , Percepção de Cores/fisiologia , Neurônios Retinianos/fisiologia , Percepção Visual/fisiologia , Adulto , Sensibilidades de Contraste/fisiologia , Eletroencefalografia , Potenciais Evocados/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa/métodos , Adulto Jovem
8.
Invest Ophthalmol Vis Sci ; 61(3): 45, 2020 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-32207814

RESUMO

Purpose: Age-related macular degeneration (AMD) is the leading cause of blindness in Western populations. While an overactive complement system has been linked to pathogenesis, mechanisms contributing to its activation are largely unknown. In aged and AMD eyes, loss of the elastin layer (EL) of Bruch's membrane (BrM) has been reported. Elastin antibodies are elevated in patients with AMD, the pathogenic significance of which is unclear. Here we assess the role of elastin antibodies using a mouse model of smoke-induced ocular pathology (SIOP), which similarly demonstrates EL loss. Methods: C57BL/6J mice were immunized with elastin or elastin peptide oxidatively modified by cigarette smoke (ox-elastin). Mice were then exposed to cigarette smoke or air for 6 months. Visual function was assessed by optokinetic response, retinal morphology by spectral-domain optical coherence tomography and electron microscopy, and complement activation and antibody deposition by Western blot. Results: Ox-elastin IgG and IgM antibodies were elevated in ox-elastin immunized mice following 6 months of smoke, whereas elastin immunization had a smaller effect. Ox-elastin immunization exacerbated smoke-induced vision loss, with thicker BrM and more damaged retinal pigment epithelium (RPE) mitochondria compared with mice immunized with elastin or nonimmunized controls. These changes were correlated with increased levels of IgM, IgG2, IgG3, and complement activation products in RPE/choroid. Conclusions: These data demonstrate that SIOP mice generate elastin-specific antibodies and that immunization with ox-elastin exacerbates ocular pathology. Elastin antibodies represented complement fixing isotypes that, together with the increased presence of complement activation seen in immunized mice, suggest that elastin antibodies exert pathogenic effects through mediating complement activation.


Assuntos
Autoanticorpos/sangue , Lâmina Basilar da Corioide/patologia , Modelos Animais de Doenças , Elastina/imunologia , Atrofia Geográfica/etiologia , Epitélio Pigmentado da Retina/patologia , Fumar/efeitos adversos , Animais , Western Blotting , Ativação do Complemento/fisiologia , Proteínas do Sistema Complemento/metabolismo , Sensibilidades de Contraste/fisiologia , Ensaio de Imunoadsorção Enzimática , Atrofia Geográfica/imunologia , Atrofia Geográfica/patologia , Imunização , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Camundongos , Camundongos Endogâmicos C57BL , Nistagmo Optocinético/fisiologia , Oxirredução , Produtos do Tabaco , Acuidade Visual/fisiologia
9.
PLoS One ; 15(2): e0228861, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32084146

RESUMO

A wireless photovoltaic retinal prosthesis is currently being studied with the aim of providing prosthetic vision to patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). The major challenge of a photovoltaic device is its limited power efficiency. Our retinal prosthetic design implements a unique divisional power supply scheme (DPSS) system that provides the electrical power generated by all of the solar cells to only a subset of electrodes at any moment in time. The aim of the present study was to systematically characterize the spatiotemporal integration performance of the system under various DPSS conditions using human subjects and a psychophysical approach. A 16x16 pixels LED array controlled by Arduino was used to simulate the output signal of the DPSS design, and human performance under different visual stimulations at various update frequencies was then used to assess the spatiotemporal capability of retinal prostheses. The results showed that the contrast polarity of the image, image brightness, and division number influenced the lower limit of the update frequency of the DPSS system, while, on the other hand, visual angle, ambient light level, and stimulation order did not affect performance significantly. Pattern recognition by visual persistence with spatiotemporal integration of multiple frames of sparse dots is a feasible approach in retinal prosthesis design. These findings provide an insight into how to optimize a photovoltaic retinal prosthesis using a DPSS design with an appropriate update frequency for reliable pattern recognition. This will help the development of a wireless device able to restore vision to RP and AMD patients in the future.


Assuntos
Fontes de Energia Elétrica , Próteses Visuais , Adulto , Sensibilidades de Contraste/fisiologia , Estimulação Elétrica , Eletrodos Implantados , Voluntários Saudáveis , Humanos , Degeneração Macular/fisiopatologia , Degeneração Macular/cirurgia , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa , Psicofísica , Retinite Pigmentosa/fisiopatologia , Retinite Pigmentosa/cirurgia , Energia Solar , Análise Espaço-Temporal , Percepção Visual/fisiologia , Tecnologia sem Fio , Adulto Jovem
10.
J Neurosci ; 40(13): 2753-2763, 2020 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-32060172

RESUMO

During binocular viewing, visual inputs from the two eyes interact at the level of visual cortex. Here we studied binocular interactions in human visual cortex, including both sexes, using source-imaged steady-state visual evoked potentials over a wide range of relative contrast between two eyes. The ROIs included areas V1, V3a, hV4, hMT+, and lateral occipital cortex. Dichoptic parallel grating stimuli in each eye modulated at distinct temporal frequencies allowed us to quantify spectral components associated with the individual stimuli from monocular inputs (self-terms) and responses due to interaction between the inputs from the two eyes (intermodulation [IM] terms). Data with self-terms revealed an interocular suppression effect, in which the responses to the stimulus in one eye were reduced when a stimulus was presented simultaneously to the other eye. The suppression magnitude varied depending on visual area, and the relative contrast between the two eyes. Suppression was strongest in V1 and V3a (50% reduction) and was least in lateral occipital cortex (20% reduction). Data with IM terms revealed another form of binocular interaction, compared with self-terms. IM response was strongest at V1 and was least in hV4. Fits of a family of divisive gain control models to both self- and IM-term responses within each cortical area indicated that both forms of binocular interaction shared a common gain control nonlinearity. However, our model fits revealed different patterns of binocular interaction along the cortical hierarchy, particularly in terms of excitatory and suppressive contributions.SIGNIFICANCE STATEMENT Using source-imaged steady-state visual evoked potentials and frequency-domain analysis of dichoptic stimuli, we measured two forms of binocular interactions: one is associated with the individual stimuli that represent interocular suppression from each eye, and the other is a direct measure of interocular interaction between inputs from the two eyes. We demonstrated that both forms of binocular interactions share a common gain control mechanism in striate and extra-striate cortex. Furthermore, our model fits revealed different patterns of binocular interaction along the visual cortical hierarchy, particularly in terms of excitatory and suppressive contributions.


Assuntos
Sensibilidades de Contraste/fisiologia , Visão Binocular/fisiologia , Córtex Visual/fisiologia , Adulto , Eletroencefalografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estimulação Luminosa
11.
Optom Vis Sci ; 97(1): 15-23, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31895273

RESUMO

SIGNIFICANCE: The first contact lens to incorporate a photochromic additive was cleared by the U.S. Food and Drug Administration last year. Because any ophthalmic lens that absorbs visible wavelengths will reduce retinal illuminance, it is important to understand the impact of this new photochromic contact lens on vision and both daytime and nighttime driving performance. PURPOSE: The purpose of this study was to evaluate the effect of senofilcon A photochromic contact lens wear on vision and driving performance under real-world conditions by comparison with a nonphotochromic contact lens and plano photochromic spectacles. METHODS: In this randomized four-visit bilateral crossover study, 24 licensed regular drivers and established wearers of soft contact lenses were enrolled. Subjects wore in random order each of three study lens types: the investigational photochromic soft contact lens (test), a nonphotochromic soft contact lens (control 1), and plano photochromic spectacle lenses (control 2). Driver performance was assessed on a closed-circuit driving track under challenging controlled conditions. The primary endpoint was overall driving performance score calculated as a composite Z score of six objective metrics. RESULTS: All 24 subjects (mean age, 29.8 years) completed the study. For nighttime driving, the adjusted mean differences in Z score (95% confidence interval) between test and control 1 and between test and control 2 were 0.069 (-0.045 to +0.183) and 0.117 (0.003 to 0.231), respectively. For daytime driving, mean differences were 0.101 (-0.013 to +0.216) between test and control 1 and 0.044 (-0.070 to +0.158) between test and control 2. Results demonstrated noninferiority of the test lens relative to controls for nighttime and daytime driving performance using a noninferiority margin of -0.25 Z score. Noninferiority was also demonstrated on all logMAR and contrast threshold testing. No adverse events were reported during the study. CONCLUSIONS: Study results revealed no evidence of concerns with either driving performance or vision while wearing photochromic contact lenses.


Assuntos
Condução de Veículo , Lentes de Contato Hidrofílicas , Hidrogéis/química , Silicones/química , Visão Ocular/fisiologia , Adulto , Sensibilidades de Contraste/fisiologia , Estudos Cross-Over , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Acuidade Visual/fisiologia
12.
Doc Ophthalmol ; 141(1): 23-32, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-31960170

RESUMO

PURPOSE: To report the clinical and electrophysiological features of cone dystrophy with supernormal rod response (CDSRR). METHODS: Retrospective cohort study of 15 unrelated patients (nine males and six females, median age 16, range 5-47 years) diagnosed with CDSRR by clinical examination, full-field electroretinography (ERG) and genetic testing. OBSERVATIONS: History, ophthalmic examination including near vision, color vision and contrast sensitivity assessment, multimodal retinal imaging and ERG. Genetic testing was done for all patients using next-generation sequencing. RESULTS: The rate of consanguinity was 86.7%. Color vision was defective in 56.3%. Near vision was defective in all patients (mean 20/160). Contrast sensitivity was affected in all patients at low contrast of 2.5%. A parafoveal ring of increased autofluorescence imaging was seen in most patients (75%). Supernormal mixed maximal response b-wave was seen bilaterally in 63% of patients (and high normal in 37%). Rod dysfunction with prolonged rod b-wave latency was detected in all. The 30-Hz flicker response was more reduced and delayed compared to the single-flash cone response. A novel homozygous missense variant c.530G>C (p.Cys177Ser) in KCNV2 was detected in one patient, the nonsense homozygous mutation c.427G>T (p.Glu143*) was found in 13 patients, and the nonsense c.159C>G (p.Tyr53*) was found in one patient. CONCLUSION: This is the largest cohort of CDSRR from a single ethnic background. Rod dysfunction and reduced 30-Hz flicker response were demonstrated in all patients. In contrast to previous descriptions in the literature, a supernormal combined dark-adapted rod-cone ERG was present in the majority of the patients at standard stimulus intensity. Considering the consistent genotype and the demonstration of likely pathogenic genetic variants in all the patients, we argue that the combination of delayed rod b-wave and subnormal flicker response strongly suggests the diagnosis of CDSRR.


Assuntos
Células Fotorreceptoras Retinianas Bastonetes/fisiologia , Retinite Pigmentosa/fisiopatologia , Adolescente , Adulto , Criança , Pré-Escolar , Códon sem Sentido/genética , Visão de Cores/fisiologia , Consanguinidade , Sensibilidades de Contraste/fisiologia , Eletrorretinografia , Feminino , Testes Genéticos , Humanos , Masculino , Pessoa de Meia-Idade , Mutação de Sentido Incorreto/genética , Estimulação Luminosa , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Células Fotorreceptoras Retinianas Cones/fisiologia , Retinite Pigmentosa/diagnóstico , Retinite Pigmentosa/genética , Estudos Retrospectivos , Adulto Jovem
13.
J Neurosci ; 40(9): 1862-1873, 2020 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-31949109

RESUMO

Neurons in the visual system integrate over a wide range of spatial scales. This diversity is thought to enable both local and global computations. To understand how spatial information is encoded across the mouse visual system, we use two-photon imaging to measure receptive fields (RFs) and size-tuning in primary visual cortex (V1) and three downstream higher visual areas (HVAs: LM (lateromedial), AL (anterolateral), and PM (posteromedial)) in mice of both sexes. Neurons in PM, compared with V1 or the other HVAs, have significantly larger RF sizes and less surround suppression, independent of stimulus eccentricity or contrast. To understand how this specialization of RFs arises in the HVAs, we measured the spatial properties of V1 inputs to each area. Spatial integration of V1 axons was remarkably similar across areas and significantly different from the tuning of neurons in their target HVAs. Thus, unlike other visual features studied in this system, specialization of spatial integration in PM cannot be explained by specific projections from V1 to the HVAs. Further, the differences in RF properties could not be explained by differences in convergence of V1 inputs to the HVAs. Instead, our data suggest that distinct inputs from other areas or connectivity within PM may support the area's unique ability to encode global features of the visual scene, whereas V1, LM, and AL may be more specialized for processing local features.SIGNIFICANCE STATEMENT Surround suppression is a common feature of visual processing whereby large stimuli are less effective at driving neuronal responses than smaller stimuli. This is thought to enhance efficiency in the population code and enable higher-order processing of visual information, such as figure-ground segregation. However, this comes at the expense of global computations. Here we find that surround suppression is not equally represented across mouse visual areas: primary visual cortex has substantially more surround suppression than higher visual areas, and one higher area has significantly less suppression than two others examined, suggesting that these areas have distinct functional roles. Thus, we have identified a novel dimension of specialization in the mouse visual cortex that may enable both local and global computations.


Assuntos
Percepção Espacial/fisiologia , Córtex Visual/fisiologia , Vias Visuais/fisiologia , Percepção Visual/fisiologia , Animais , Axônios/fisiologia , Mapeamento Encefálico , Sensibilidades de Contraste/fisiologia , Feminino , Locomoção/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/fisiologia , Estimulação Luminosa , Pupila/fisiologia , Campos Visuais
14.
Am J Ophthalmol ; 211: 207-216, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31837317

RESUMO

PURPOSE: We investigated the adaptability and acceptance of a novel spectacle lens design that was recently reported to achieve a significant antimyopia effect. DESIGN: A prospective, cross-over study. METHODS: Twenty children were recruited to wear both Defocus Incorporated Multiple Segments (DIMS) and single vision (SV) lens, with a random assignment of which type of lens was experienced first. For each type of lens, high and low contrast central distant visual acuity (VA) and high contrast mid-peripheral near VA were measured at both 500 lux and 50 lux ambient illuminance after 30 minutes' and a week's wearing of the lens. A self-developed questionnaire was applied to evaluate the visual discomfort at the 1-week visit. All quantitative data were analyzed by paired t test, while qualitative data were analyzed with the χ2 or Wilcoxon signed-rank tests. RESULTS: Central VA was not affected by DIMS lens compared with SV lens in all circumstances (all P > .05). However, the mid-peripheral near VA was found to reduce by approximately 0.06 logarithm of minimal angle of resolution unit in 2 of 4 quadrants (500 lux; P < .05) and in 3 quadrants (50 lux; P < .05) for DIMS lenses. No improvement was detected in the 1-week visit. Mid-peripheral blurred vision was the main visual complaint, which was noticed only once or twice a day. Being aware of the average antimyopic efficacy, 90% of children subjects preferred DIMS lenses. CONCLUSION: Mid-peripheral vision through DIMS lenses was slightly affected compared with SV lenses. Otherwise, DIMS lenses received good tolerance and acceptance by Chinese children.


Assuntos
Adaptação Ocular/fisiologia , Grupo com Ancestrais do Continente Asiático/etnologia , Óculos , Miopia/terapia , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Adolescente , Adulto , Criança , China/epidemiologia , Sensibilidades de Contraste/fisiologia , Estudos Cross-Over , Feminino , Humanos , Masculino , Miopia/etnologia , Miopia/fisiopatologia , Estudos Prospectivos , Desenho de Prótese , Inquéritos e Questionários , Acuidade Visual/fisiologia , Adulto Jovem
15.
Eur J Ophthalmol ; 30(1): 201-208, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30556416

RESUMO

PURPOSE: To evaluate the long-term objective and subjective results of a trifocal intraocular lens. METHODS: Prospective observational study enrolling 24 eyes that underwent uneventful microincisional cataract surgery with bilateral implantation of a diffractive trifocal intraocular lens (FineVision Micro F, PhysIOL, Belgium). After a mean follow-up period of 60 ± 2 months, patients answered the 10-item Near Activity Vision Questionnaire (NAVQ-10) and were assessed for uncorrected and corrected distance, intermediate and near visual acuity, defocus curve, light-distortion analysis, and total ocular aberrometry with a pyramidal wavefront sensor (Osiris, CSO, Italy). RESULTS: There was significant improvement of uncorrected visual acuity at all distances in all eyes (p < 0.01). The distorsion index and best-fit circle radius were significantly lower in binocular conditions (p = 0.02). Mean Rasch score at NAVQ-10 was 16.29 ± 11.57. Patients reported to be completely, very, and moderately satisfied with their uncorrected near vision in 67%, 25%, and 8% of cases, respectively. We found no significant correlation between patient satisfaction scores at near vision satisfaction questionnaire and other variables such as light-distortion analysis or wavefront aberrometry parameters. CONCLUSION: The studied diffractive trifocal intraocular lens provides good and stable long-term results for distance, intermediate, and near vision, with high levels of patient satisfaction at long-term follow-up. The intraocular lens' light-distortion effect is less disturbing in binocular conditions and may have its perception down-modulated by neuroadaptation over time.


Assuntos
Aberrações de Frente de Onda da Córnea/fisiopatologia , Implante de Lente Intraocular , Lentes Intraoculares Multifocais , Satisfação do Paciente/estatística & dados numéricos , Facoemulsificação , Acuidade Visual/fisiologia , Aberrometria , Idoso , Sensibilidades de Contraste/fisiologia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Pseudofacia/fisiopatologia , Refração Ocular/fisiologia , Inquéritos e Questionários , Resultado do Tratamento
16.
Eur J Ophthalmol ; 30(2): 299-306, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30739479

RESUMO

OBJECTIVE: To compare visual quality in patients implanted with Tecnis® monofocal (ZCB00) and multifocal (ZMB00) intraocular lenses taking into account their optical quality measured in vitro with an eye model. METHODS: In total, 122 patients participated in this study: 44 implanted with monofocal and 78 with multifocal intraocular lenses. Measurements of visual acuity and contrast sensitivity were performed. The optical quality of the intraocular lenses was evaluated in three image planes (distance, intermediate and near) using an eye model on a test bench. The metric considered was the area under the curve of the modulation transfer function. RESULTS: Optical quality at the far focus of the monofocal intraocular lens (area under the curve of the modulation transfer function = 66.97) was considerably better than that with the multifocal lens (area under the curve of the modulation transfer function = 32.54). However, no significant differences were observed between groups at the distance-corrected visual acuity. Distance-corrected near vision was better in the multifocal (0.15 ± 0.20 logMAR) than that in the monofocal group (0.43 ± 0.21 logMAR, p < 0.001), which correlated with the better optical quality at near reached by the multifocal intraocular lens (area under the curve of the modulation transfer function = 29.11) in comparison with the monofocal intraocular lens (area under the curve of the modulation transfer function = 5.0). In intermediate vision, visual acuity was 0.28 ± 0.16 logMAR (multifocal) and 0.36 ± 0.14 logMAR (monofocal) with p = 0.014, also in good agreement with the values measured in the optical quality (area under the curve of the modulation transfer function = 10.69 (multifocal) and 8.86 (monofocal)). The contrast sensitivity was similar in almost all frequencies. Pelli-Robson was slightly better in the monofocal (1.73) than in the multifocal group (1.64; p = 0.023). CONCLUSION: Patients implanted with multifocal ZMB00 achieved a distance visual acuity similar to those implanted with monofocal ZCB00, but showed significantly better intermediate and near visual acuity. A correlation was found between intraocular lenses' optical quality and patients' visual acuity. Contrast sensitivity was very similar between the multifocal and monofocal groups.


Assuntos
Implante de Lente Intraocular , Lentes Intraoculares , Lentes Intraoculares Multifocais , Acuidade Visual/fisiologia , Idoso , Sensibilidades de Contraste/fisiologia , Feminino , Humanos , Lentes Intraoculares/normas , Masculino , Pessoa de Meia-Idade , Lentes Intraoculares Multifocais/normas
17.
Doc Ophthalmol ; 140(1): 83-93, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31489519

RESUMO

PURPOSE: When evaluating ophthalmological devices and procedures, for instance those for visual electrophysiology, it is often desirable to perform tests with reduced acuity. Doing this with individuals with actual visual impairments has a number of disadvantages, such as considerable recruitment efforts, especially when a specific acuity range is targeted, and little control about the actual perceptual characteristics of the impairment, which are normally not fully known. Lenses with positive diopters or blurring filters that are placed in front of the eyes of visually normal observers promise a simple solution to the problem. However, defocus results in considerable spurious resolution, and previous studies suggest that the frequently used Bangerter occluders are not optimal for the purpose. The present study therefore reviews a number of other options and tests a selection of filters with respect to their effect on acuity and contrast sensitivity with the aim of identifying filters that primarily degrade acuity while mostly sparing contrast sensitivity. METHODS: First, we screened several filters for potential usefulness. The Freiburg Acuity and Contrast Test was then used to measure visual acuity and contrast sensitivity with a subset of three filters (Luminit LSD 0.5° and 1°, and LEE 420) and, for comparison, with a Bangerter occluder with a nominal acuity grade of 0.1. A qualitative comparison of the filters' effect on the checkerboard-reversal VEP was also performed. RESULTS: With both Luminit filters, variability in acuity across participants was relatively small, and at least with the 0.5° version, contrast sensitivity was relativity little affected. The LEE filter and the Bangerter occluder resulted in more variability and, compared to the effect on acuity, a relatively strong reduction in contrast sensitivity. Comparing the Luminit 0.5° and 1° filters, the reduction of acuity was not proportional to physical stimulus degradation. The effect on VEP responses was consistent with the psychophysical data. CONCLUSIONS: The Luminit filters, which have a Gaussian light diffusion profile, appear to be a good choice for artificial reduction of acuity.


Assuntos
Filtração/instrumentação , Acuidade Visual/fisiologia , Adulto , Sensibilidades de Contraste/fisiologia , Eletrorretinografia , Feminino , Humanos , Masculino
18.
Vision Res ; 166: 33-42, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31841707

RESUMO

The purpose of the present study was to assess the accommodative response and pupillary dynamics while reading passages with different text-background color combinations on an LCD screen. Twenty healthy young adults read fourteen 2-min passages designed with fourteen different color combinations between text and background, while the accommodative and pupil responses were continuously measured with a binocular open-field autorefractometer. Our results revealed that the text-background color combination modulates the accommodative and pupillary dynamics during a 2-minutes reading task. The blue-red combination induced a heightened accommodative response, whereas positive polarities were associated with more variability of the accommodative response and smaller pupil sizes. Participants reported lower perceived ratings of legibility for text-background color combination with lower luminance contrast (white-yellow). The manipulation of text-background color did not have a significant effect on reading speed. These results may have important applications in the design of digital visual interfaces.


Assuntos
Acomodação Ocular/fisiologia , Percepção de Cores/fisiologia , Sensibilidades de Contraste/fisiologia , Pupila/fisiologia , Leitura , Adulto , Feminino , Humanos , Luz , Masculino , Adulto Jovem
19.
Vision Res ; 166: 52-59, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31855668

RESUMO

Both luminance contrast and character size are critical factors affecting reading performance. Previous studies reported on the effect of luminance contrast on the reading-speed function, that is, the relationship between reading speed and character size. In particular, when contrast was reduced, the critical print size (CPS) was found to shift to a larger character size even though the maximum reading speed and function shape did not change [Japanese Journal of Ophthalmology 52(1) (2008) 44-47]. In the present study, the effect of luminance contrast on the reading function was quantitatively examined. Japanese phrases with a luminance contrast of 0.03-0.99 were prepared as stimuli. Observers with normal vision were asked to read aloud phrases with several character sizes. Then, the reading functions were obtained for each luminance contrast. CPS was found to increase as the luminance contrast decreased. The relationship between contrast and CPS was linear in log-log coordinates, that is, log-CPS increased as the log-contrast of the characters decreased. It was found that the contrast of the stimulus systematically affects the location of the reading function.


Assuntos
Sensibilidades de Contraste/fisiologia , Luz , Leitura , Adulto , Grupo com Ancestrais do Continente Asiático , Humanos , Idioma , Testes Visuais , Adulto Jovem
20.
Optom Vis Sci ; 96(12): 940-947, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31834154

RESUMO

SIGNIFICANCE: Contour interaction describes an impairment of visual acuity produced by nearby flanking features, which exerts a significant impact in many clinical tests of visual acuity. Our results indicate that the magnitude of interaction depends either on the flanker contrast energy (i.e., the product of flanker contrast and width) or the flanker contrast alone, depending on the contrast energy of the flankers. PURPOSE: The discrimination of acuity targets is impaired by the presence of nearby flanking contours, a phenomenon known as contour interaction. METHODS: In this study, we measured percent correct identification for threshold size, high-contrast Sloan letters at the fovea and at 5° in the inferior visual field for different combinations of flanking-bar width, and Weber contrast corresponding to specific fixed values of contrast energy (width × contrast, in %-min arc). RESULTS: For flanking bars with low-contrast energy, contour interaction exhibited no systematic dependence on the flanking-bar width. However, when the flanking bars had higher contrast energy, narrower high-contrast bars produced significantly greater contour interaction than wider bars of lower contrast. CONCLUSIONS: The results are consistent with the interpretation that contour interaction depends primarily on the contrast energy of flanking contours when their contrast energy is low. As the contrast energy of the flanking contours increases, the magnitude of contour interaction depends on the flanker contrast. For high-contrast flanking contours, the magnitude of contour interaction saturates when the width of the flanking contours is approximately 20% of letter size.


Assuntos
Sensibilidades de Contraste/fisiologia , Percepção de Forma/fisiologia , Adulto , Idoso , Feminino , Fóvea Central , Humanos , Masculino , Pessoa de Meia-Idade , Acuidade Visual/fisiologia , Campos Visuais/fisiologia
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