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Viewing repetitive striped patterns can induce pattern glare, experienced as visual discomfort (VD). While previous studies examined either pupillary responses or VD separately, few have investigated how they covary or evolve with repeated exposure. This study tested whether pupillary dynamics could serve as potential physiological indicator of individual visual sensitivity beyond subjective reports. Across four experiments (preliminary: = 97; main: = 70 for spatial frequency, = 46 for central field size, = 36 for central blank, with partial overlap), we manipulated spatial frequency, central field size, and surround field size of square-wave gratings (0.5-3 s) while measuring both discomfort and pupil size. Higher spatial frequencies and larger pattern areas elicited stronger pupillary constriction and greater discomfort, whereas repeated exposures produced cumulative increases in discomfort and decreases in baseline pupil size, consistent with visual strain rather than adaptation. To assess the potential of pupillometry as an indicator of visual discomfort, we examined individual differences in the main spatial-frequency experiment (controlled viewing distance, = 42). A paradoxical pattern emerged: within participants, stronger stimuli produced greater constriction, but individuals with higher overall discomfort showed weaker constriction and stronger late redilation. Similar dissociations between subjective sensitivity and pupillary responses have been noted in studies of light-induced discomfort, suggesting that related mechanisms may contribute, although their specific physiological basis remains unclear. Overall, our findings clarify how pattern-induced discomfort evolves over time and across individuals and highlight pupillometry's potential as a sensitive, physiological tool for assessing visual sensitivity.

Much of the neural machinery of the early visual cortex, from the extraction of local orientations to contextual modulations through lateral interactions, is thought to have developed to provide a sparse encoding of contour in natural scenes, allowing the brain to process efficiently most of the visual scenes we are exposed to. Certain visual stimuli, however, cause visual stress, a set of adverse effects ranging from simple discomfort to migraine attacks, and epileptic seizures in the extreme, all phenomena linked with an excessive metabolic demand. The theory of efficient coding suggests a link between excessive metabolic demand and images that deviate from natural statistics. Yet, the mechanisms linking energy demand and image spatial content in discomfort remain elusive. Here, we used theories of visual coding that link image spatial structure and brain activation to characterize the response to images observers reported as uncomfortable in a biologically based neurodynamic model of the early visual cortex that included excitatory and inhibitory layers to implement contextual influences. We found three clear markers of aversive images: a larger overall activation in the model, a less sparse response, and a more unbalanced distribution of activity across spatial orientations. When the ratio of excitation over inhibition was increased in the model, a phenomenon hypothesised to underlie interindividual differences in susceptibility to visual discomfort, the three markers of discomfort progressively shifted toward values typical of the response to uncomfortable stimuli. Overall, these findings propose a unifying mechanistic explanation for why there are differences between images and between observers, suggesting how visual input and idiosyncratic hyperexcitability give rise to abnormal brain responses that result in visual stress.

Altered subjective visual sensitivity manifests as feelings of discomfort or overload elicited by intense and irritative visual stimuli. This can result in a host of visual aberrations including visual distortions, elementary visual hallucinations and visceral responses like dizziness and nausea, collectively referred to as \"pattern glare.\" Current knowledge of the underlying neural mechanisms has focused on overall excitability of the visual cortex, but the individual contribution of excitatory and inhibitory systems has not yet been quantified. In this study, we focus on the role of glutamate and γ-aminobutyric acid (GABA) as potential mediators of individual differences in subjective visual sensitivity, measured by a computerized Pattern Glare Test-a series of monochromatic square-wave gratings with three different spatial frequencies, while controlling for psychological variables related to sensory sensitivity with multiple questionnaires. Resting neurotransmitter concentrations in primary visual cortex (V1) and right anterior insula were studied in 160 healthy participants using magnetic resonance spectroscopy. Data showed significant differences in the perception of visual distortions (VD) and comfort scores between men and women, with women generally reporting more VD, and therefore the modulatory effect of sex was considered in a further examination. A general linear model analysis showed a negative effect of occipital glutamate on a number of reported visual distortions, but also a significant role of several background psychological traits. When assessing comfort scores in women, an important intervening variable was the menstrual cycle. Our findings do not support that baseline neurotransmitter levels have a significant role in overreactivity to aversive stimuli in neurotypical population. However, we demonstrated that biological sex can have a significant impact on subjective responses. Based on this additional finding, we suggest that future studies investigate aversive visual stimuli while examining the role of biological sex.

Visual discomfort is related to the statistical regularity of visual images. The contribution of luminance contrast to visual discomfort is well understood and can be framed in terms of a theory of efficient coding of natural stimuli, and linked to metabolic demand. While color is important in our interaction with nature, the effect of color on visual discomfort has received less attention. In this study, we build on the established association between visual discomfort and differences in chromaticity across space. We average the local differences in chromaticity in an image and show that this average is a good predictor of visual discomfort from the image. It accounts for part of the variance left unexplained by variations in luminance. We show that the local chromaticity difference in uncomfortable stimuli is high compared to that typical in natural scenes, except in particular infrequent conditions such as the arrangement of colorful fruits against foliage. Overall, our study discloses a new link between visual ecology and discomfort whereby discomfort arises when adaptive perceptual mechanisms are overstimulated by specific classes of stimuli rarely found in nature.

Background: Chronic work-related stress, including exposure to mobbing, is associated with a wide range of psychological and somatic consequences. However, its potential impact on visual function, particularly in the absence of structural ocular damage, remains underexplored. This narrative review critically examines the evidence linking chronic stress, autonomic nervous system (ANS) dysregulation, and functional visual disorders, focusing on accommodative function and asthenopia. Methods: A qualitative narrative review of the literature published between 2000 and 2025 was conducted using major biomedical databases. Studies addressing chronic stress, ANS activity, accommodative function, digital eye strain, and functional ocular symptoms were identified and integrated into a coherent pathophysiological framework. Results: The ocular system, being richly innervated by the ANS, may represent a peripheral target of prolonged stress-related autonomic alterations. Available evidence suggests that chronic stress is associated with asthenopia, accommodative inefficiency, and ocular discomfort even in the absence of overt ocular pathology. In particular, altered parasympathetic control of the ciliary muscle emerges as a plausible mediating mechanism. Conclusions: Functional visual disorders may represent peripheral manifestations of stress-related ANS dysregulation. Although causality cannot be established conclusively, the proposed framework supports the need for multidisciplinary research to clarify the clinical and medico-legal relevance of stress-related visual dysfunction.

Visual discomfort prediction (VDP) is used to evaluate a user’s visual discomfort when viewing stereoscopic images. The focus of this study is to explore more representative and distinctive features to describe complex visual discomfort perception. We consider integrating hand-crafted features and high-level semantic features based on deep learning to describe discomfort perception, and propose a multi-task VDP model (M2VDP) based on multi-view feature fusion. In particular, the model reinforces the positive effects of scene structure and depth difference on visual discomfort, and dynamically learns high-level semantic features at different scales by constructing a multi-scale neural network structure. In addition, using the multi-task learning, the prediction task of discomfort score can be guided by correctly classifying the discomfort level of stereoscopic images. The proposed method is verified on the public IEEE-SA database, and the results show that the proposed method achieves optimal performance. The ablation experimental results show that the multi-view feature fusion structure and multi-task learning are effective.

Purpose Convergence and accommodative insufficiency represent the main cause of complaints during close visual work and can reduce visual performance and comfort. Knowing their prevalence among schoolchildren is fundamental to define strategies for action. The purpose of this study was to estimate the frequency of these conditions in children in 5th and 6th school years in inland Portugal and to assess the impact that each visual condition has on their quality of life, based on the level of visual symptoms. Methods a cross-sectional study was carried out with children enrolled in the 5th and 6th school years. 372 children (192 girls) were assessed, with average ages of 10.9 ± 0.9 years. Refractive error and binocular vision assessment, integrating accommodative parameters, were used to analyse the visual condition. Symptoms were quantified using the Portuguese version of the CISS (Convergence Insufficiency Symptom Survey). Results The prevalence of definite Convergence Insufficiency (CI) in the children assessed was 2%. A prevalence of 6,8% could be considered if clinically significant CI (high suspect and definite categories) cases are accounted. In relation to Accommodative Insufficiency (AI), a frequency rate of 10% was recorded, with 3% of the evaluated children presenting AI and CI simultaneously. The symptoms score was higher in AI than in CI. Conclusions A frequency of approximately 10% was found for each one of the visual syndromes, and it was verified that visual discomfort is common among teenagers who carry these conditions. In cases of asthenopia, such as headaches and loss of concentration, associated with near vision activities, there is a requirement to evaluate the quality of binocular vision.

Since electroencephalogram (EEG) signals can directly provide information on changes in brain activity due to behaviour changes, how to assess visual discomfort through EEG signals attracts researchers’ attention. However, previous assessments based on time-domain EEG features lack sufficient consideration of the dependence among EEG signals, which may affect the discrimination to visual discomfort. Although the copula model can explore the dependence among variables, the EEG-based copula models still have the following deficiencies: (1) the methods ignoring the fine-grained information hidden in EEG signals could make the estimated marginal density function improper, and (2) the approaches neglecting the pseudo-correlation among data may inappropriately estimate the correlation matrix parameter of the copula density function. The mixture kernel density estimation (MKDE) and remedied correlation matrix (RCM) on the EEG-based copula model are proposed to mitigate the mentioned shortcomings. The simulation experiments show that MKDE can not only better estimate the marginal density function but also explore fine-grained information. The RCM can be closer to the real correlation matrix parameter. With the favourable quality of the proposed EEG-based model, it is used to extract time-domain EEG features to assess visual discomfort further. To our best knowledge, the extracted features present better discrimination to visual discomfort compared with the features extracted by the state-of-the-art method.

Background Discomfort evoked by stereoscopic depth has been widely concerned. Previous studies have proposed a comfortable disparity range and considered that disparities exceed this range would cause visual discomfort. Brain activity recordings including Electroencephalograph (EEG) monitoring enable better understanding of perceptual and cognitive processes related to stereo depth-induced visual comfort. Methods EEG data was collected using a stereo-visual evoked potential (VEP) test system by providing visual stimulus to subjects aged from 21 to 25 with normal stereoscopic vision. For each type of visual stimulus, data were processed using directed transfer function (DTF) and adaptive directed transfer function (ADTF) in combination with subjective feedbacks (comfort or discomfort). The topographies of information flow were constructed to compare responses stimulated by different stereoscopic depth, and to determine the difference in comfort and discomfort situations upon stimulation with same stereoscopic depth. Results Based on EEG analysis results, we found that the occipital P270 was moderately related to the disparity. Moreover, the ADTF of P270 showed that the information flows at frontal lobe and central-parietal lobe changed when stimulation with different stereoscopic depth applied. As to the stereo images with same stereoscopic depth, the DTF outflows at the temporal and temporal-parietal lobes in δ band, central and central-parietal lobes in α and θ bands, and the comparison of inflows in these three bands could be considered as discriminated indexes for matching the stereoscopic effect with viewers’ comfort or discomfort state impacted by disparity. The subjective feedbacks indicated that the comfort judgments remained as a result of cumulative effect. Conclusions This study proposed a short-term stereo-VEP experiment that shorted the duration of each stimulus in the experimental scheme to minimize the interference from other factors except the disparity. The occipital P270 had a mid-relevance to the disparity and its ADTF showed the affected areas when viewers are receiving stimulations with different disparities. DTF could be considered as discriminated indexes for matching the stereoscopic effect with viewers’ comfort or discomfort state induced by disparity. This study proposed a preferable experiment to observe the single effect of disparity and provided an intuitive and easy-to-read result in a more convenient manner.

Objectives: To assess the mismatch between the clinical observation of vitreous alterations and self-reported symptoms in young patients complaining of symptomatic vitreous opacities (SVO). Methods: The ophthalmic medical records of young patients presenting primarily with SVO were retrospectively evaluated. Symptoms severity was assessed using a questionnaire. The status of the vitreous body was examined with indirect ophthalmoscopy at the slit-lamp and classified according to an ad hoc severity scale. Results: Sixty eyes of thirty otherwise healthy patients (median age: 32.5 (IQR: 29.0–37.0) years old) complaining of SVO (median duration: 38 months; interquartile range: 18–84 months) were enrolled. SVO was rated as severe by 50% of participants, affecting all the activities explored in the questionnaire. Twenty-three patients (76.6%) reported SVO-related depression and/or anxiety, for which eleven patients (36.6%) were or had been using medication. Fifty-eight eyes (96.6%) showed no evidence of (or minimal) vitreous opacity, while two eyes (3.3%) were found to have significant vitreous opacity. No significant inter-gender differences (p > 0.05) and no significant differences (p > 0.05) were found between the severity of vitreous opacity and patients’ reported symptoms nor with their psychological status and medication use. Conclusions: Severe discomfort related to the perception of vitreous floaters exists in young patients whose vitreous gel examination is unremarkable or shows only minor alterations. We believe this discrepancy can be explained by optical anisotropy; significant forward-scattering of light, which results in floater symptoms; and reduced back reflection, which limits the clinical observation.