Search

The analysis of eye movements has proven valuable for understanding brain function and the neuropathology of various disorders. This research aims to utilize eye movement data analysis as a screening tool for differentiation between eight different groups of pathologies, including scholar, neurologic, and postural disorders. Leveraging a dataset from 20 clinical centers, all employing AIDEAL and REMOBI eye movement technologies this study extends prior research by considering a multi-annotation setting, incorporating information from recordings from saccade and vergence eye movement tests, and using contextual information (e.g. target signals and latency of the eye movement relative to the target and confidence level of the quality of eye movement recording) to improve accuracy while reducing noise interference. Additionally, we introduce a novel hybrid architecture that combines the weight-sharing feature of convolution layers with the long-range capabilities of the transformer architecture to improve model efficiency and reduce the computation cost by a factor of 3.36, while still being competitive in terms of macro F1 score. Evaluated on two diverse datasets, our method demonstrates promising results, the most powerful discrimination being Attention & Neurologic; with a macro F1 score of up to 78.8%; disorder. The results indicate the effectiveness of our approach in classifying eye movement data from different pathologies and different clinical centers accurately, thus enabling the creation of an assistant tool in the future. [ABSTRACT FROM AUTHOR]

• Vertical vergence was triggered by optic flow and visual rotations in all planes. • The degree of vergence was correlated with increased instability and stress. • Visually induced vertical vergence likely reflects subcortical vestibular activity. The present study explored visually induced vertical vergence (VIVV) as non-specific motion processing response. Healthy participants (7 male, mean age 28.57 ± 2.30; 9 female, mean age 27.67 ± 3.65) were exposed to optokinetic stimuli in an HTC VIVE virtual reality headset while VIVV, pupil-size, and postural sway was recorded. The methodology was shown to produce VIVV in the roll plane at 30 deg/s. Subsequent trials consisted of 40 s optokinetic motion in yaw, pitch, and roll directions at 60 deg/s, and radial optic flow; optokinetic directions were inverted after 20 s of motion. Median VIVV amplitude changes were normalized to the clockwise roll rotation, analysed, and correlated with changes in pupil-size and body sway. VIVV, pupil-size, and body sway were all affected by changes in optokinetic direction. Post-hoc analyses showed significant VIVV responses during optokinetic yaw and pitch rotations, as well as during radial optic flow stimulations. VIVV magnitudes were universally correlated with pupil-size and body sway. In conclusion, VIVV was expressed in all tested dimensions and may consequently serve as a visual motion processing biomarker. Failing to support binocularity while responding to optokinetic directionality, VIVV may reflect an eye-movement response associated with increased postural instability and stress, similar to a dorsal light reflex. [ABSTRACT FROM AUTHOR]

Self-supervised learning (SSL) has gained significant attention in the past decade for its capacity to utilize non-annotated datasets to learn meaningful data representations. In the medical domain, the challenge of constructing large annotated datasets presents a significant limitation, rendering SSL an ideal approach to address this constraint. In this study, we introduce a novel pretext task tailored to stimulus-driven eye movement data, along with a denoising task to improve the robustness against simulated eye tracking failures. Our proposed task aims to capture both the characteristics of the pilot (brain) and the motor (eye) by learning to reconstruct the eye movement position signal using up to 12.5% of the unmasked eye movement signal patches, along with the entire REMOBI target signal. Thus, the encoder learns a high-dimensional representation using a multivariate time series of length 8192 points, corresponding to approximately 40 s. We evaluate the learned representation on screening eight distinct groups of pathologies, including dyslexia, reading disorder, and attention deficit disorder, across four datasets of varying complexity and size. Furthermore, we explore various head architecture designs along with different transfer learning methods, demonstrating promising results with improvements of up to approximately 15%, leading to an overall macro F1 score of 61% and 61.5% on the Saccade and the Vergence datasets, respectively. Notably, our method achieves macro F1 scores of 64.7%, 66.1%, and 61.1% for screening dyslexia, reading disorder, and attention deficit disorder, respectively, on clinical data. These findings underscore the potential of self-learning algorithms in pathology screening, particularly in domains involving complex data such as stimulus-driven eye movement analysis. [ABSTRACT FROM AUTHOR]

Fusional vergence range tests are commonly used in optometric practice. The aim of this study was to investigate the possible contribution of CA/C, AC/A, and proximal cues (PCT) to the magnitude and presence of blur and recovery during the measurement of fusional vergence ranges and to determine whether the occurrence of blur is influenced by these vergence and accommodation cues. A total of 27 participants with normal binocular vision were included and AC/A, CA/C, and PCT ratios were evaluated. Blur, break, and recovery values in convergence and divergence were assessed with base-out and base-in prisms, respectively. No statistical correlations were found between AC/A, CA/C, and PCT ratios and the magnitude of blur, break, and recovery values in neither far, near, convergence, nor divergence testing conditions. However, better near point of convergence values were related to higher break values in convergence at far distances, but not at near distances. In addition, for convergence and far distance, a statistical difference was found between groups reporting and not reporting blur in AC/A stimulus and PCT ratios. The present results cannot confirm whether vergence and accommodation cues, such as AC/A, CA/C, and PCT ratios, may play an active role during the assessment of fusional vergence range. [ABSTRACT FROM AUTHOR]

Postural stabilization is essential to effectively interact with our environment. Humans preemptively adjust their posture to counteract impending disturbances, such as those encountered during interactions with moving objects, a phenomenon known as anticipatory postural adjustments (APAs). APAs are thought to be influenced by predictive models that incorporate object motion via retinal motion and extraretinal signals. Building on our previous work that examined APAs in relation to the perceived momentum of moving objects, here we explored the impact of object motion within different visual field sectors on the human capacity to anticipate motion and prepare APAs for contact between virtual moving objects and the limb. Participants interacted with objects moving toward them under different gaze conditions. In one condition, participants fixated on either a central point (central fixation) or left-right of the moving object (peripheral fixation), whereas in another, they followed the moving object with smooth pursuit eye movements (SPEMs). We found that APAs had the smallest magnitude in the central fixation condition and that no notable differences in APAs were apparent between the SPEM and peripheral fixation conditions. This suggests that the visual system can accurately perceive motion of objects in peripheral vision for posture stabilization. Using Bayesian model averaging, we also evaluated the contribution of different gaze variables, such as eye velocity and gain (ratio of eye and object velocity) and showed that both eye velocity and gain signals were significant predictors of APAs. Taken together, our study underscores the roles of oculomotor signals in the modulation of APAs. NEW & NOTEWORTHY: We show that the human visuomotor system can detect motion in peripheral vision and make anticipatory adjustments to posture before contact with moving objects, just as effectively as when the eye movement system tracks those objects with smooth pursuit eye movements. These findings pave the way for research into how age-induced changes in spatial vision, eye movements, and motion perception could affect the control of limb movements and postural stability during motion-mediated interactions with objects. [ABSTRACT FROM AUTHOR]

Introduction: Visual function deficits have been reported in adolescents following concussion. We compared vergence and accommodation deficits in paediatric and adolescent patients at a tertiary medical centre in the sub‐acute (15 days to 12 weeks) and chronic (12 weeks to 1 year) phases of concussion recovery. Methods: The study included patients aged 7 to <18 years seen between 2014 and 2021, who had a binocular vision (BV) examination conducted within 15 days and 1 year of their concussion injury. Included patients had to have 0.10 logMAR monocular best‐corrected vision or better in both eyes and be wearing a habitual refractive correction. BV examinations at near included measurements of near point of convergence, convergence and divergence amplitudes, vergence facility, monocular accommodative amplitude and monocular accommodative facility. Vergence and accommodation deficits were diagnosed using established clinical criteria. Group differences were assessed using nonparametric statistics and ANCOVA modelling. Results: A total of 259 patients were included with 111 in the sub‐acute phase and 148 in the chronic phase of concussion recovery. There was no significant difference in the rates of vergence deficits between the two phases of concussion recovery (sub‐acute = 48.6%; chronic = 49.3%). There was also no significant difference in the rates of accommodation deficits between the two phases of concussion recovery (sub‐acute = 82.0%; chronic = 77.0%). Conclusion: Patients in both the sub‐acute and chronic phases of concussion recovery exhibited a high frequency of vergence and accommodation deficits, with no significant differences between groups. Results indicate that patients exhibiting vision deficits in the sub‐acute phase may not resolve without intervention, though a prospective, longitudinal study is required to test the hypothesis. [ABSTRACT FROM AUTHOR]

Abstract The analysis of eye movements has proven valuable for understanding brain function and the neuropathology of various disorders. This research aims to utilize eye movement data analysis as a screening tool for differentiation between eight different groups of pathologies, including scholar, neurologic, and postural disorders. Leveraging a dataset from 20 clinical centers, all employing AIDEAL and REMOBI eye movement technologies this study extends prior research by considering a multi-annotation setting, incorporating information from recordings from saccade and vergence eye movement tests, and using contextual information (e.g. target signals and latency of the eye movement relative to the target and confidence level of the quality of eye movement recording) to improve accuracy while reducing noise interference. Additionally, we introduce a novel hybrid architecture that combines the weight-sharing feature of convolution layers with the long-range capabilities of the transformer architecture to improve model efficiency and reduce the computation cost by a factor of 3.36, while still being competitive in terms of macro F1 score. Evaluated on two diverse datasets, our method demonstrates promising results, the most powerful discrimination being Attention & Neurologic; with a macro F1 score of up to 78.8%; disorder. The results indicate the effectiveness of our approach in classifying eye movement data from different pathologies and different clinical centers accurately, thus enabling the creation of an assistant tool in the future.

In this study, the challenges posed by limited annotated medical data in the field of eye movement AI analysis are addressed through the introduction of a novel physiologically based gaze data augmentation library. Unlike traditional augmentation methods, which may introduce artifacts and alter pathological features in medical datasets, the proposed library emulates natural head movements during gaze data collection. This approach enhances sample diversity without compromising authenticity. The library evaluation was conducted on both CNN and hybrid architectures using distinct datasets, demonstrating its effectiveness in regularizing the training process and improving generalization. What is particularly noteworthy is the achievement of a macro F1 score of up to 79% when trained using the proposed augmentation (EMULATE) with the three HTCE variants. This pioneering approach leverages domain-specific knowledge to contribute to the robustness and authenticity of deep learning models in the medical domain.

Ocular torsion and vertical divergence reflect the brain's sensorimotor integration of motion through the vestibulo-ocular reflex (VOR) and the optokinetic reflex (OKR) to roll rotations. Torsion and vergence however express different response patterns depending on several motion variables, but research on their temporal dynamics remains limited. This study investigated the onset times of ocular torsion (OT) and vertical vergence (VV) during visual, vestibular, and visuovestibular motion, as well as their relative decay rates following prolonged optokinetic stimulations. Temporal characteristics were retrieved from three separate investigations where the level of visual clutter and acceleration were controlled. Video eye-tracking was used to retrieve the eye-movement parameters from a total of 41 healthy participants across all trials. Ocular torsion consistently initiated earlier than vertical vergence, particularly evident under intensified visual information density, and higher clutter levels were associated with more balanced decay rates. Additionally, stimulation modality and accelerations affected the onsets of both eye movements, with visuovestibular motion triggering earlier responses compared to vestibular motion, and increased accelerations leading to earlier onsets for both movements. The present study showed that joint visuovestibular responses produced more rapid onsets, indicating a synergetic sensorimotor process. It also showed that visual content acted as a fusional force during the decay period, and imposed greater influence over the torsional onset compared to vergence. Acceleration, by contrast, did not affect the temporal relationship between the two eye movements. Altogether, these findings provide insights into the sensorimotor integration of the vestibulo-ocular and optokinetic reflex arcs. [ABSTRACT FROM AUTHOR]

In this study, the challenges posed by limited annotated medical data in the field of eye movement AI analysis are addressed through the introduction of a novel physiologically based gaze data augmentation library. Unlike traditional augmentation methods, which may introduce artifacts and alter pathological features in medical datasets, the proposed library emulates natural head movements during gaze data collection. This approach enhances sample diversity without compromising authenticity. The library evaluation was conducted on both CNN and hybrid architectures using distinct datasets, demonstrating its effectiveness in regularizing the training process and improving generalization. What is particularly noteworthy is the achievement of a macro F1 score of up to 79% when trained using the proposed augmentation (EMULATE) with the three HTCE variants. This pioneering approach leverages domain-specific knowledge to contribute to the robustness and authenticity of deep learning models in the medical domain. [ABSTRACT FROM AUTHOR]

Concussion, which is usually associated with head injuries, has received considerable attention in recent years because of its possible long-term cognitive and visual consequences. The review summarised the mild traumatic brain injury literature. Pupillary dynamics, which are primarily mediated by the autonomic nervous system, play an important function in regulating the amount of light entering the eye, but they can be dramatically impacted after a concussion. This can result in aberrant pupillary responses, which may have ramifications for light sensitivity, a common post-concussion symptom. In concussed individuals, accommodation and vergence – the visual processes responsible for focusing on near and distant objects – might be interrupted, potentially leading to fuzzy vision, eyestrain, and difficulty with tasks that require precise visual coordination. Understanding the delicate interplay between these three components of vision in the setting of concussions is critical for creating more targeted diagnostic and rehabilitative techniques, ultimately enhancing the quality of life for those who have had head injuries. [ABSTRACT FROM AUTHOR]

Background: Oculomotor dysfunctions are common visual problems following mild traumatic brain injury (TBI). They not only produce vision discomfort and possible loss of visual efficiency, but they may also negatively affect the overall rehabilitative process. It is important for clinicians to be aware of the visual symptoms and the possible treatments for oculomotor dysfunctions. Case Report: A 44-year-old TBI patient with complaints of blurred near vision, visual discomfort, and reduced peripheral vision was examined. He was diagnosed with fusional vergence dysfunction and saccadic dysfunction. The treatment consisted of eight in-office vision therapy sessions every one to two weeks and daily home exercises. The post-treatment examination showed increased vergence ranges, improved stereopsis, and better saccadic function. The patient reported a reduction in visual complaints. Conclusion: This case report indicates that officebased vision therapy is effective in reducing visual symptoms and improving oculomotor dysfunctions after mild traumatic brain injury. [ABSTRACT FROM AUTHOR]

This cross-sectional study examined eye movement performance in patients aged 4 to 16 years. Measurements of eye movements were obtained before and after performing therapy for inhibition of four primitive reflexes, asymmetric tonic neck reflex, symmetric tonic neck reflex, labyrinthine tonic reflex and Moro reflex. Subsequently the scores of the four primitive reflexes were compared with the results of five variables: fixation maintenance, % mean saccade size, motility excursions, fixations during excursions and mean duration of fixations. The comparisons showed a significant reduction in evidence of fixation maintenance as well as mean saccade size due to the inhibition of the four primitive reflexes. There was also a significant increase in ocular motility while fixations per saccade and average duration of fixations also decreased significantly. Visual balance between values of both eyes improved in all tests. A device called VisagraphTM III, which measures eye movements, was used for data collection. These results suggest that the oculomotor improvements reflect the involvement of other maturational processes such as the emergence and inhibition of primitive reflexes, the whole reorganization being key to future reading and attentional processes. [ABSTRACT FROM AUTHOR]

Early detection of dyslexia and learning disorders is vital for avoiding a learning disability, as well as supporting dyslexic students by tailoring academic programs to their needs. Several studies have investigated using supervised algorithms to screen dyslexia vs. control subjects; however, the data size and the conditions of data acquisition were their most significant limitation. In the current study, we leverage a large dataset, containing 4243 time series of eye movement records from children across Europe. These datasets were derived from various tests such as saccade, vergence, and reading tasks. Furthermore, our methods were evaluated with realistic test data, including real-life biases such as noise, eye tracking misalignment, and similar pathologies among non-scholar difficulty classes. In addition, we present a novel convolutional neural network architecture, adapted to our time series classification problem, that is intended to generalize on a small annotated dataset and to handle a high-resolution signal (1024 point). Our architecture achieved a precision of 80.20% and a recall of 75.1%, when trained on the vergence dataset, and a precision of 77.2% and a recall of 77.5% when trained on the saccade dataset. Finally, we performed a comparison using our ML approach, a second architecture developed for a similar problem, and two other methods that we investigated that use deep learning algorithms to predict dyslexia. [ABSTRACT FROM AUTHOR]

This cross-sectional study examined eye movement performance in patients aged 4 to 16 years. Measurements of eye movements were obtained before and after performing therapy for inhibition of four primitive reflexes, asymmetric tonic neck reflex, symmetric tonic neck reflex, labyrinthine tonic reflex and Moro reflex. Subsequently the scores of the four primitive reflexes were compared with the results of five variables: fixation maintenance, % mean saccade size, motility excursions, fixations during excursions and mean duration of fixations. The comparisons showed a significant reduction in evidence of fixation maintenance as well as mean saccade size due to the inhibition of the four primitive reflexes. There was also a significant increase in ocular motility while fixations per saccade and average duration of fixations also decreased significantly. Visual balance between values of both eyes improved in all tests. A device called VisagraphTM III, which measures eye movements, was used for data collection. These results suggest that the oculomotor improvements reflect the involvement of other maturational processes such as the emergence and inhibition of primitive reflexes, the whole reorganization being key to future reading and attentional processes

Early detection of dyslexia and learning disorders is vital for avoiding a learning disability, as well as supporting dyslexic students by tailoring academic programs to their needs. Several studies have investigated using supervised algorithms to screen dyslexia vs. control subjects; however, the data size and the conditions of data acquisition were their most significant limitation. In the current study, we leverage a large dataset, containing 4243 time series of eye movement records from children across Europe. These datasets were derived from various tests such as saccade, vergence, and reading tasks. Furthermore, our methods were evaluated with realistic test data, including real-life biases such as noise, eye tracking misalignment, and similar pathologies among non-scholar difficulty classes. In addition, we present a novel convolutional neural network architecture, adapted to our time series classification problem, that is intended to generalize on a small annotated dataset and to handle a high-resolution signal (1024 point). Our architecture achieved a precision of 80.20% and a recall of 75.1%, when trained on the vergence dataset, and a precision of 77.2% and a recall of 77.5% when trained on the saccade dataset. Finally, we performed a comparison using our ML approach, a second architecture developed for a similar problem, and two other methods that we investigated that use deep learning algorithms to predict dyslexia.

AIM: To compare the vergence mechanisms between good and poor sleepers in university students. METHODS: A total of 64 university students were recruited in this study. The validated Malay version of Pittsburgh Sleep Quality Index questionnaire (PSQI-M) was used to measure the participants' sleep quality over the past month. Participants were categorized as good sleepers (n=32) and poor sleepers (n=32) based on the PSQI-M scores. Heterophoria and fusional vergences were measured at distance and near. Mann-Whitney U test was used to compare heterophoria, negative fusional vergence (NFV), and positive fusional vergence (PFV) at distance and near between good and poor sleepers. Spearman correlation analysis was used to study the relationship between PSQI-M score and PFV at distance. RESULTS: Both distance and near heterophorias were not significantly different between good and poor sleepers (P>0.05). There was a difference in distance PFV (P0.05). Distance PFV was negatively correlated with PSQI-M score (rs=-0.33, P

Fusional vergence range tests are commonly used in optometric practice. The aim of this study was to investigate the possible contribution of CA/C, AC/A, and proximal cues (PCT) to the magnitude and presence of blur and recovery during the measurement of fusional vergence ranges and to determine whether the occurrence of blur is influenced by these vergence and accommodation cues. A total of 27 participants with normal binocular vision were included and AC/A, CA/C, and PCT ratios were evaluated. Blur, break, and recovery values in convergence and divergence were assessed with base-out and base-in prisms, respectively. No statistical correlations were found between AC/A, CA/C, and PCT ratios and the magnitude of blur, break, and recovery values in neither far, near, convergence, nor divergence testing conditions. However, better near point of convergence values were related to higher break values in convergence at far distances, but not at near distances. In addition, for convergence and far distance, a statistical difference was found between groups reporting and not reporting blur in AC/A stimulus and PCT ratios. The present results cannot confirm whether vergence and accommodation cues, such as AC/A, CA/C, and PCT ratios, may play an active role during the assessment of fusional vergence range.

Objective features of abnormal eye movements in PD and to discuss the structures and pathways through which these abnormalities may manifest. [ABSTRACT FROM AUTHOR]

Aims: To evaluate the impact of smartphone gaming on the vergence system of the eye. Settings and Design: A 5-month (from March 2023 to August 2023) comparative and experimental research was conducted. Materials and Methods: Eighty-two participants with a mean age of 21.98 ± 2.26 years were present in the study. Prior to assessing accommodation and vergence system characteristics, participants underwent a comprehensive eye examination. The participants were asked to play a shooting game on a smartphone for 30 minutes at a 40 cm distance. Measurements of the vergence parameters were taken before and after the activity and afterwards were compared. Statistical Analysis: Non-parametric tests were used to compare pre- and post-task measurements. The Wilcoxon signed-rank test was used to compare the variables: Negative fusional vergence (NFV), Positive fusional vergence (PFV), Near point of convergence (NPC), and Vergence Facility (VF), with the alpha error set at 5%. Results: The mean age of the participants was 21.98 ± 2.26 years. Post-task, the vergence parameters: NPC (p < 0.001), NFV for near distance (p < 0.001), PFV for near distance (p < 0.001), and VF (p < 0.001) showed significant decrease in vergence parameters. Conclusions: The study shows smartphone gaming for 30 minutes affects the vergence system, leading to binocular vision anomalies in young individuals.

Background: Self-reported diplopia is described in up to one-third of Parkinson’s disease (PD) patients. Objective: The purpose of our study was to expand our understanding of the mechanistic underpinnings of diplopia in PD. We hypothesize that the time-based control of eye alignment and increased eye deviation under binocular viewing will be related to the fusion-initiating and fusion-maintaining component deficits of disparity-driven vergence in PD. Methods: We used high-resolution video-oculography to measure eye alignment under binocular and monocular viewing and disparity-driven vergence in 33 PD and 10 age-matched healthy participants. We computed eye deviation and time-based control of eye alignment, occurrence of conjugate saccadic eye movements, latency and gain of vergence (fusion initiation), and variance of eye position at the end of dynamic vergence (fusion maintenance). Results: We categorized PD subjects into three groups, considering their timebased control of eye alignment as compared to healthy controls in binocular viewing. Group 1 = 45% had good control and spent >80% of the time when the eyes were well-aligned, Group 2 = 26% had intermediate control and spent <80% but greater >5% of the time when the eyes were well-aligned, and Group 3 = 29% had very poor control with increased eye deviation majority of the times (<5% of the time when the eyes were well-aligned). All three groups exhibited greater eye deviation under monocular viewing than controls. PD subjects exhibited fusion-initiating and fusion-maintaining vergence deficits (prolonged latencies, reduced vergence gain, increased variance of fusion-maintaining component) with a greater probability of saccadic movements than controls. Group 2 and Group 3 subjects were more likely to exhibit failure to initiate vergence (>20%) than Group 1 (13%) and controls (0%) trials. No significant difference was found in the Unified Parkinson’s Disease Rating Scale (UPDRS—a tool to measure the severity of PD) values between the three PD groups (Group 1 = 33.69 ± 14.22, Group 2 = 38.43 ± 22.61, and Group 3 = 23.44 ± 1, p > 0.05). Conclusion: The majority of PD subjects within our cohort had binocular dysfunction with increased eye deviation under monocular viewing and disparity-driven vergence deficits. PD subjects with intermediate or poor control of eye deviation under binocular viewing had greater fusion-initiating and fusion-maintaining vergence deficits. The study highlights the importance of assessing binocular dysfunction in PD subjects independent of the severity of motor symptoms. [ABSTRACT FROM AUTHOR]

BackgroundSelf-reported diplopia is described in up to one-third of Parkinson’s disease (PD) patients.ObjectiveThe purpose of our study was to expand our understanding of the mechanistic underpinnings of diplopia in PD. We hypothesize that the time-based control of eye alignment and increased eye deviation under binocular viewing will be related to the fusion-initiating and fusion-maintaining component deficits of disparity-driven vergence in PD.MethodsWe used high-resolution video-oculography to measure eye alignment under binocular and monocular viewing and disparity-driven vergence in 33 PD and 10 age-matched healthy participants. We computed eye deviation and time-based control of eye alignment, occurrence of conjugate saccadic eye movements, latency and gain of vergence (fusion initiation), and variance of eye position at the end of dynamic vergence (fusion maintenance).ResultsWe categorized PD subjects into three groups, considering their time-based control of eye alignment as compared to healthy controls in binocular viewing. Group 1 = 45% had good control and spent >80% of the time when the eyes were well-aligned, Group 2 = 26% had intermediate control and spent 5% of the time when the eyes were well-aligned, and Group 3 = 29% had very poor control with increased eye deviation majority of the times (20%) than Group 1 (13%) and controls (0%) trials. No significant difference was found in the Unified Parkinson’s Disease Rating Scale (UPDRS—a tool to measure the severity of PD) values between the three PD groups (Group 1 = 33.69 ± 14.22, Group 2 = 38.43 ± 22.61, and Group 3 = 23.44 ± 1, p > 0.05).ConclusionThe majority of PD subjects within our cohort had binocular dysfunction with increased eye deviation under monocular viewing and disparity-driven vergence deficits. PD subjects with intermediate or poor control of eye deviation under binocular viewing had greater fusion-initiating and fusion-maintaining vergence deficits. The study highlights the importance of assessing binocular dysfunction in PD subjects independent of the severity of motor symptoms.

Purpose: Individuals with different types of intermittent exotropia (IXT) may use neurally coupled accommodation and vergence responses differently from those without exotropia to achieve eye alignment. This study examined the relationship between simultaneously recorded accommodation and vergence responses in children and young adults with a range of types of IXT while aligned and deviated. Methods: Responses of 29 participants with IXT (4–31 years) and 24 age‐matched controls were recorded using simultaneous eye‐tracking and eccentric photorefraction while they watched a movie in binocular or monocular viewing at varying viewing distances. Gradient response AC/A ratios and fusional vergence ranges were also assessed. Eight participants had divergence or pseudo‐divergence excess type IXT, 5 had convergence insufficiency and 16 had basic IXT. Results: Control and IXT participants accommodated similarly both in monocular and binocular‐aligned conditions to visual targets at 80 and 33 cm. When deviated in binocular viewing, most participants with IXT exhibited changes in accommodation <0.5D relative to alignment. Gradient response AC/A ratios were similar for control [0.56 MA/D (IQR: 0.51 MA/D)] and IXT participants [0.42 MA/D (0.54 MA/D); p = 0.60]. IXT participants showed larger vergence to accommodation ratios with changes from distance to near fixation [1.19 MA/D (1.45 MA/D)] than control participants [0.78 MA/D (0.60 MA/D); p = 0.02], especially among IXT participants with divergence or pseudo‐divergence excess. Participants with IXT exhibited typical fusional divergence ranges beyond their dissociated position [8.86 Δ (7.10 Δ)] and typical fusional convergence ranges from alignment [18 Δ (15.75 Δ)]. Conclusions: This study suggests that control of IXT is typically neither driven by accommodative convergence alone nor associated with over‐accommodation secondary to fusional convergence efforts. These simultaneous measurements confirmed that proximal vergence contributed significantly to IXT control, particularly for divergence or pseudo‐divergence excess type IXT. For IXT participants in this study, achieving eye alignment did not conflict with having clear vision. [ABSTRACT FROM AUTHOR]

PURPOSE: The aim of this study is to investigate the association between body mass index (BMI) and visual efficiency skills of university students. METHODS: This study adopted an analytical and descriptive methodology whereby a comprehensive screening of 385 university students was conducted. Ultimately, 116 subjects were selected to ensure judicious distribution of subjects across the four categories of BMI. These 116 subjects were subjected to visual efficiency testing parameters, as referenced from "Clinical Management of Binocular Vision," by Scheiman and Wick. RESULTS: BMI and visual efficiency anomalies were observed to be correlated with statistical significance to each other as indicated by a P = 0.018 and χ2 = 15.22. It was also observed that the obese category exhibited the highest prevalence of accommodation and vergence anomalies, followed by the underweight category, as discerned from a detailed analysis of subjects classified according to the BMI categories. These findings imply a noteworthy and potentially deleterious impact of BMI on the visual system and underscore the importance of regular screening for visual efficiency skills in individuals across various BMI categories. CONCLUSION: This study established a compelling association between BMI and visual efficiency skills anomalies. Consistent with prior research, the findings of this study suggest that individual with higher BMI is more prone to experiencing such anomalies. [ABSTRACT FROM AUTHOR]

Introduction: Coordinated alignment of the eyes during gaze fixation and eye movements are an important component of normal visual function. We have previously described the coordinated behavior of convergence eye movements and pupillary responses using a 0.1 Hz binocular disparity-driven sine profile and a step profile. The goal of this publication is to further characterize ocular vergence-pupil size coordination over a wider range of frequencies of ocular disparity stimulation in normal subjects. Methods: Binocular disparity stimulation is generated by presentation of independent targets to each eye on a virtual reality display, while eye movements and pupil size are measured by an embedded video-oculography system. This design allows us to study two complimentary analyses of this motion relationship. First, a macroscale analysis describes the vergence angle of the eyes in response to binocular disparity target movement and pupil area as a function of the observed vergence response. Second, a microscale analysis performs a piecewise linear decomposition of the vergence angle and pupil relationship to permit more nuanced findings. Results: These analyses identified three main features of controlled coupling of pupil and convergence eye movements. First, a near response relationship operates with increasing prevalence during convergence (relative to the "baseline" angle); the coupling is higher with increased convergence in this range. Second, the prevalence of "near response"-type coupling decreases monotonically in the diverging direction; the decrease persists after the targets move (converge back) from maximum divergence toward the baseline positions, with a minimum prevalence of near response segments near the baseline target position. Third, an opposite polarity pupil response is infrequent, but tends to be more prevalent when the vergence angles are at maximum convergence or divergence for a sinusoidal binocular disparity task. Discussion: We suggest that the latter response is an exploratory "rangevalidation" when binocular disparity is relatively constant. In a broader sense, these findings describe operating characteristics of the near response in normal subjects and form a basis for quantitative assessments of function in conditions such as convergence insufficiency and mild traumatic brain injury. [ABSTRACT FROM AUTHOR]

Binocular Near Eye Displays require matching between the focus of the displayed image and the convergence of the two eyes. We present simple test methods for determining both the virtual focus and the vergence distance in Near Eye Displays. [ABSTRACT FROM AUTHOR]

We demonstrate the realization of a very low energy, on-the-eye vergence-type distance ranger based on sensing of a locally uniform vector field, specifically the earth’s magnetic field. This ranging method is passive, only requiring measurement of the magnetic field vector at both eyeballs utilizing magnetometer chips placed on the eye scleral regions. The eye vergence angle and range distance are calculated from these two vector quantities. The method can obtain a range reading with as little as 118 nJ of energy consumed per eye for 3.3V and 50 nJ when operated at 1.9V. This method is thus suitable for applications where energy storage is very limited such as in smart contacts vision correcting microsystems.

BACKGROUND: During near-viewing, the vestibulo-ocular reflex (VOR) response/gain increases to compensate for the relatively larger translation of the eyes with respect to the target. OBJECTIVE: To review vergence-mediated gain increase (VMGI) testing methods stimuli and responses (latency and amplitude), peripheral/central pathways and clinical relevance. METHODS: The authors discuss publications listed in PUBMED since 1980 in the light of their own studies. RESULTS: The VMGI can be measured during rotational, linear and combined head accelerations. It has short-latency, non-compensatory amplitude, and relies on irregularly discharging peripheral afferents and their pathways. It is driven by a combination of perception, visual-context and internal modelling. CONCLUSIONS: Currently, there are technical barriers that hinder VMGI measurement in the clinic. However, the VMGI may have diagnostic value, especially with regards to measuring otolith function. The VMGI also may have potential value in rehabilitation by providing insight about a patient's lesion and how to best tailor a rehabilitation program for them, that potentially includes VOR adaptation training during near-viewing. [ABSTRACT FROM AUTHOR]

BACKGROUND: Accommodation and Vergence disorder are diverse visual anomalies which can interfere with a child's school performance and impair one's ability to function efficiently. Its association with refractive error and its intervention were studied less in Indian myopia children; hence, there is a need for research in such setting. METHOD: One hundred and fifty Indian adolescents aged 10 to 17 years were divided into three refractive error groups (high, moderate, and low myopia). Baseline vision examination and a comprehensive binocular vision assessment were performed on all eligible adolescents. Vision therapy was provided to participants whose parents gave consent on behalf of the children. Chi-square analysis was utilized to look at the association between the groups of refractive errors. To compare the mean constants of the experimental and control groups, a two-way RM ANOVA was performed. RESULTS: The most common dysfunction found in low myopia (75.3%), and moderate myopia (54%) was convergence insufficiency. High myopes (62.8%) were found to have combined convergence and accommodative insufficiency followed by accommodative dysfunction (14%) and basic exophoria (6%). In moderate myopia, a significant relationship was found between this dysfunction and refractive error. The experimental group in the overall sample showed statistically significant improvement after vision therapy (P<0.001), in comparison to the control group. CONCLUSION: Refractive error is linked to accommodative and convergence insufficiency. Thus, vergence and accommodative impairment must be tested for all myopic children, and vision therapy should be advised along with spectacle prescription for efficient binocular vision. [ABSTRACT FROM AUTHOR]

We built a new binocular near eye DFD display system. In order to display two virtual images at different viewing distances from the observer, which is necessary for DFD image, we employed time division driving of the LCD. Furthermore, using this DFD display system, visual fatigue was evaluated when observing 3D image by binocular near eye DFD and 3D image with only vergence. We suggested that 3D image by binocular near eye DFD causes less visual fatigue than 3D image with only vergence. [ABSTRACT FROM AUTHOR]

IntroductionCoordinated alignment of the eyes during gaze fixation and eye movements are an important component of normal visual function. We have previously described the coordinated behavior of convergence eye movements and pupillary responses using a 0.1 Hz binocular disparity-driven sine profile and a step profile. The goal of this publication is to further characterize ocular vergence-pupil size coordination over a wider range of frequencies of ocular disparity stimulation in normal subjects.MethodsBinocular disparity stimulation is generated by presentation of independent targets to each eye on a virtual reality display, while eye movements and pupil size are measured by an embedded video-oculography system. This design allows us to study two complimentary analyses of this motion relationship. First, a macroscale analysis describes the vergence angle of the eyes in response to binocular disparity target movement and pupil area as a function of the observed vergence response. Second, a microscale analysis performs a piecewise linear decomposition of the vergence angle and pupil relationship to permit more nuanced findings.ResultsThese analyses identified three main features of controlled coupling of pupil and convergence eye movements. First, a near response relationship operates with increasing prevalence during convergence (relative to the “baseline” angle); the coupling is higher with increased convergence in this range. Second, the prevalence of “near response”-type coupling decreases monotonically in the diverging direction; the decrease persists after the targets move (converge back) from maximum divergence toward the baseline positions, with a minimum prevalence of near response segments near the baseline target position. Third, an opposite polarity pupil response is infrequent, but tends to be more prevalent when the vergence angles are at maximum convergence or divergence for a sinusoidal binocular disparity task.DiscussionWe suggest that the latter response is an exploratory “range-validation” when binocular disparity is relatively constant. In a broader sense, these findings describe operating characteristics of the near response in normal subjects and form a basis for quantitative assessments of function in conditions such as convergence insufficiency and mild traumatic brain injury.

In the current study, we tested the hypothesis that Mild Cognitive Impairment (MCI) patients can be identified based on the analysis of vergence eye movements and pupil responses. We recorded vergence and pupil responses in MCI patients (N = 22) and cognitive healthy elderly (N = 18) while performing a visual oddball task. Based on selected features, a classifier model computed probability scores predicting MCI. MCI patients were re-evaluated in a follow-up visit of 12–18 months. For validating the model, patients with Alzheimer's Disease (AD) (N = 9) were tested. High classification accuracy was obtained (AUC: 0.93). In addition, the probability scores showed significant predictive power of MCI conversion into possible AD. Our results show that MCI can be detected by assessing vergence and pupil responses during a simple and short task. Therefore, these responses could potentially be used as a marker tool for MCI diagnosis and to identify the risk of developing Alzheimer's Disease.

Vision provides a key sensory input for the performance of fine motor skills, which are fundamentally important to daily life activities, as well as skilled occupational and recreational performance. Binocular visual function is a crucial aspect of vision that requires the ability to combine inputs from both eyes into a unified percept. Summation and fusion are two aspects of binocular processing associated with performance advantages, including more efficient visuomotor control of upper limb movements. This paper uses the multiple processes model of limb control to explore how binocular viewing could facilitate the planning and execution of prehension movements in adults and typically developing children. Insight into the contribution of binocularity to visuomotor control also comes from examining motor performance in individuals with amblyopia, a condition characterized by reduced visual acuity and poor binocular function. Overall, research in this field has advanced our understanding of the role of binocular vision in the development and performance of visuomotor skills, the first step towards developing assessment tools and targeted rehabilitation for children with neurodevelopment disorders at risk of poor visuomotor outcomes. This article is part of a discussion meeting issue 'New approaches to 3D vision'. [ABSTRACT FROM AUTHOR]

Introduction: Maddox suggested that there were four convergence subtypes, each driven by a different stimulus. The purpose of this study was to assess the neural correlates for accommodative convergence, proximal convergence (convergence stimulus provided), disparity convergence and voluntary convergence (no specific convergence stimulus provided) using functional magnetic resonance imaging (fMRI). Methods: Ten subjects (mean age = 24.4 years) with normal binocular vision participated. The blood oxygenation level‐dependent (BOLD) signals of the brain from fMRI scans were measured when subjects made vergence eye movements while: (1) alternately viewing letters monocularly where one eye viewed through a −2.00 D lens, (2) alternately viewing Difference of Gaussian targets monocularly at distance and near, (3) viewing random dot stereograms with increasing disparity and (4) voluntarily converging the eyes with binocular viewing. Results: The accommodative convergence paradigm resulted in activation on the right side in the right fusiform cortex and the right middle occipital cortex. The proximal convergence stimulus mainly activated areas in the right occipital lobe. The disparity stimulus activated areas in the left occipital cortex and the left frontal cortex. Finally, the voluntary convergence paradigm resulted in activation primarily in the occipital lobe and mostly bilaterally. Conclusion: The accommodative, proximal, disparity and voluntary convergence paradigms resulted in activation in unique areas in the brain with functional MRI. Activation was found in more areas in the proximal and voluntary conditions compared with the accommodative and disparity conditions. [ABSTRACT FROM AUTHOR]

Electronic holography is an ideal 3-D display technique to ameliorate the vergence-accommodation conflict, which is a possible cause of visual fatigue and discomfort from viewing conventional stereoscopic 3-D displays. Previous studies have measured accommodative and vergence responses to holographic images and to real objects, and the results showed that these responses are in good agreement. To demonstrate the effectiveness of electronic holography as a possible solution to the vergence-accommodation conflict caused by viewing conventional stereoscopic 3-D displays, we measured both accommodative and vergence responses to reconstructed images of holograms and super multiview holographic stereograms. We also measured responses to real objects located at various distances and conventional two-view stereo images for comparison. The results indicate that the accommodative responses to the electro-holographic display and super multiview holographic stereogram change with the vergence response in a similar manner, as is the case with real objects as compared to conventional two-view stereo display. This suggests that the electronic holographic display and super multiview holographic stereograms are promising candidates for resolving the vergence-accommodation conflict. [ABSTRACT FROM AUTHOR]

Perceiving other people's direct gaze is important for many areas of everyday activity. For horizontal and vertical eye movements, the area of being looked at, known as the cone of gaze, has been well explored. Previous research has shown a range of eye rotations (up to eccentricities of 4°–9°) that people accept as direct gaze. Vergence is an important cue for perceiving the depth of fixation. This study examines the range of vergence angles that support the perception of being looked at. In two experiments, observers adjusted the degree of vergence of the lookers' eyes until they felt just (not) looked at. The first experiment also asked to adjust the point of being exactly looked at, which was 0° (parallel eyes). The thresholds of being just (not) looked at were around 4.5° of convergence and 2.5° divergence, which results in a depth of 7° of vergence. This depth was replicated in Experiment 2, while the thresholds of convergence (3.5°) and divergence (3.5°) slightly differ from Experiment 1. The results indicate a consistent area of vergences being accepted as direct gaze, yielding first-time evidence for a third dimension—the depth dimension—of direct gaze. [ABSTRACT FROM AUTHOR]

Previous studies have revealed unexpected relationships between the firing rates of horizontally acting motoneurons and vergence. During a vergence task, for example, antidromically identified abducens internuclear neurons show a negative correlation between vergence angle and firing rate, which is the opposite of the modulation displayed by the medial rectus motoneurons to which they project. For a given horizontal eye position, medial rectus motoneurons discharge at a higher rate if the eyes are converged than if the same eye position is reached during a task that requires version; paradoxically, however, the horizontal rectus eye muscles show corelaxation during vergence. These complex and unexpected relationships inspired the present author to investigate whether the tonic firing rates of vertically acting motoneurons in oculomotor nucleus are correlated with vergence angle. Monkeys were trained to fixate a single, randomly selected, visual target among an array of 60 red plus-shaped LEDs, arranged at 12 different distances in three-dimensional space. The targets were arranged to permit dissociation of vertical eye position and vergence angle. Here I report, for the first time, that most vertically acting motoneurons in oculomotor nucleus show a significant negative correlation between tonic firing rate and vergence angle. This suggests the possibility that there may be a general corelaxation of extraocular muscles during vergence. NEW & NOTEWORTHY An array of 60 plus-shaped LEDs, positioned at various locations in three-dimensional space, was used to elicit conjugate and disjunctive saccades while single neurons in oculomotor nucleus were recorded from rhesus monkeys. This study demonstrates that most vertically acting motoneurons in oculomotor nucleus discharge at a lower rate when the eyes are converged. [ABSTRACT FROM AUTHOR]