Infrared Eye Tracker Research Articles

Retinal "sweet spot" for myopia treatment.

We studied which retinal area controls short-term axial eye shortening when human subjects were exposed to + 3.0D monocular defocus. A custom-built infrared eye tracker recorded the point of fixation while subjects watched a movie at a 2m distance. The eye tracker software accessed each individual movie frame in real-time and covered the points of fixation in the movie with a uniform grey patch. Four patches were programmed: (1) foveal patch (0-3 degrees), (2) annular patch (3-9deg), (3) foveal patch (0-3deg) combined with an annular patch (6-9deg), and (4) full-field patch where only 6-10deg were exposed to the defocus. Axial eye shortening was elicited similarly with full-field positive defocus and with the foveal patch, indicating that the fovea made only a minor contribution (-11 ± 12μm vs. -14 ± 17μm, respectively, n.s.). In contrast, patching a 3-9 degrees annular area or fovea together with an annular area of 6-9 degrees, completely suppressed the effect when compared with full-field defocus (+ 3 ± 1μm or -2 ± 13μm vs. -11 ± 12μm, respectively, p < 0.001). Finally, we found that the near-peripheral retina (6-10 degrees) is a "sweet spot" for positive defocus detection and alone can regulate eye growth control mechanism, and perhaps long-term refractive development (-9 ± 8μm vs. full-field: -11 ± 12μm, n.s.).

Tunnel motion: Pupil dilations to optic flow within illusory dark holes.

We showed to the same observers both dynamic and static 2D patterns that can both evoke distinctive perceptions of motion or optic flow, as if moving in a tunnel or into a dark hole. At all times pupil diameters were monitored with an infrared eye tracker. We found a converging set of results indicating stronger pupil dilations to expansive growth of shapes or optic flows evoking a forward motion into a dark tunnel. Multiple regression analyses showed that the pupil responses to the illusory expanding black holes of static patterns were predicted by the individuals' pupil response to optic flows showing spiraling motion or "free fall" into a black hole. Also, individuals' pupil responses to spiraling motion into dark tunnels predicted the individuals' sense of illusory expansion with the static, illusory expanding, dark holes. This correspondence across individuals between their pupil responses to both dynamic and static, illusory expanding, holes suggests that these percepts reflect a common perceptual mechanism, deriving motion from 2D scenes, and that the observers' pupil adjustments reflect the direction and strength of motion they perceive and the expected outcome of an increase in darkness.

Flicker adaptation improves acuity for briefly presented stimuli by reducing crowding.

Adaptation to flickering/dynamic noise improves visual acuity for briefly presented stimuli (Arnold et al., 2016). Here, we investigate whether such adaptation operates directly on our ability to see detail or by changing fixational eye movements and pupil size or by reducing visual crowding. Following earlier work, visual acuity was measured in observers who were either unadapted or who had adapted to a 60-Hz flickering noise pattern. Participants reported the orientation of a white tumbling-T target (four-alternative forced choice [4AFC], ⊤⊣⊥⊢). The target was presented for 110 ms either in isolation or flanked by randomly oriented T's (e.g., ⊣⊤⊢) followed by an isolated (+) or flanked (+++) mask, respectively. We measured fixation stability (using an infrared eye tracker) while observers performed the task (with and without adaptation). Visual acuity improved modestly (around 8.4%) for flanked optotypes following adaptation to flicker (mean, -0.038 ± 0.063 logMAR; p = 0.015; BF10 = 3.66) but did not when measured with isolated letters (mean, -0.008 ± 0.055 logMAR; p = 0.5; BF10 = 0.29). The magnitude of acuity improvement was associated with individuals' (unadapted) susceptibility to crowding (the ratio of crowded to uncrowded acuity; r = -0.58, p = 0.008, BF10 = 7.70) but to neither fixation stability nor pupil size. Confirming previous reports, flicker improved acuity for briefly presented stimuli, but we show that this was only the case for crowded letters. These improvements likely arise from attenuation of sensitivity to a transient low spatial frequency (SF) image structure (Arnold et al., 2016; Tagoh et al., 2022), which may, for example, reduce masking of high SFs by low SFs. We also suggest that this attenuation could reduce backward masking and so reduce foveal crowding.

Combined diagnosis for Parkinson's disease via gait and eye movement disorders

Background and objectivesWith the discovery of the potential role of gait and eye movement disorders in Parkinson's disease (PD) recognition, we intend to investigate the combined diagnostic value of gait and eye movement disorders for PD. MethodsWe enrolled some Chinese PD patients and healthy controls and separated them into the training and validation sets based on enrollment time. Performance in five oculomotor paradigms and in one gait paradigm was examined using an infrared eye tracking device and a wearable gait analysis device. We developed and validated a combined model for PD diagnosis via multivariate stepwise logistic regression analysis. Furthermore, subgroup comparisons and multi-model comparison were performed to assess its applicability and advantages. ResultsA total of 145 PD patients and 80 healthy controls in China were recruited. The pro-saccade velocity, the trunk-sway max, and the turn mean angular velocity were finally screened out for the model development. Incorporating age factor, the ternary model demonstrated more satisfactory performance on ROC (AUC of 0.953 in the training set and AUC of 0.972 in the validation set), calibration curve, and decision curve. A nomogram was drawn to visualize the model. The combined model outperforms individual models with a broad application and the unique diagnostic value for early detection of PD patients, especially TD-PD patients. ConclusionWe demonstrated the presence of gait and eye movement disorders, as well as the feasibility, applicability, and superiority of employing them together to diagnose PD.

Success rates, near-response patterns, and learning trends with free-fusion stereograms

Free-fusion stereograms are routinely used for demonstrating various stereoscopic effects. Yet, untrained observers find it challenging to perform this task. This study showed that only less than 1/3rd of sixty-one pre-presbyopic adults with normal binocular vision could successfully free-fuse random-dot image pairs and identify the stereoscopic shapes embedded in these patterns. Another one-third of participants performed the task with poor success rates, while the remaining could not perform the task. There was a clear dissociation of vergence and accommodative responses in participants who were successful with free-fusion, as recorded using a dynamic infrared eye tracker and photorefractor. Those in the unsuccessful cluster either showed strong vergence and accommodation or weak vergence and strong accommodation during the task. These response patterns, however, were specific to the free-fusion task because all these participants generated good convergence/accommodation to real-world targets and to conflicting vergence and accommodative demands stimulated with prisms or lenses. Task performance of the unsuccessful cluster also improved significantly following pharmacological paralysis of accommodation and reached the performance levels of the successful cluster. A minority of participants also appeared to progressively learn to dissociate one of the two directions of their vergence and accommodation crosslinks with repeated free-fusion trials. These results suggest that successful free-fusion might depend upon how well participants generate a combination of volitional and reflex vergence responses to large differences in disparity with conflicting static accommodative demands. Such responses would require that only one direction of the vergence-accommodation crosslinks be active at any given time. The sequence of near-responses could also be learnt through repeated trials to optimize task performance.

Associations of prenatal exposure to per- and polyfluoroalkyl substances (PFAS) with measures of cognition in 7.5-month-old infants: An exploratory study

BackgroundPrenatal exposure to per- and polyfluoroalkyl substances (PFAS) has been linked to a wide array of adverse maternal and child health outcomes. However, studies examining PFAS in relation to offspring cognition have been inconclusive. ObjectiveWe examined whether prenatal exposure to a mixture of PFAS was related to cognition in 7.5-month-old infants. MethodsOur analytic sample included participants enrolled in the Chemicals in Our Bodies (CIOB) and Illinois Kids Development Study (IKIDS) cohorts (N = 163). Seven PFAS were measured in 2nd trimester maternal serum samples and were detected in >65% of participants. Infant cognition was measured with a visual recognition memory task using an infrared eye tracker when infants were 7.5 months old. This task included familiarization trials where each infant was shown two identical faces and test trials where each infant was shown the familiar face paired with a novel face. In familiarization, we assessed average run duration (time looking at familiarization stimuli before looking away) as a measure of information processing speed, in addition to time to familiarization (time to reach 20 s of looking at stimuli) and shift rate (the number of times infants looked between stimuli), both as measures of attention. In test trials, we assessed novelty preference (proportion of time looking to the novel face) to measure recognition memory. Linear regression was used to estimate associations of individual PFAS with cognitive outcomes, while Bayesian kernel machine regression (BKMR) was used to estimate mixture effects. ResultsIn adjusted single-PFAS linear regression models, an interquartile range increase in PFNA, PFOA, PFOS, PFHxS, PFDeA, and PFUdA was associated with an increase in shift rate, reflecting better visual attention. Using BKMR, increasing quartiles of the PFAS mixture was similarly associated with a modest increase in shift rate. There were no significant associations between PFAS exposure and time to reach familiarization (another measure of attention), average run duration (information processing speed), or novelty preference (visual recognition memory). ConclusionIn our study population, prenatal PFAS exposure was modestly associated with an increase in shift rate and was not strongly associated with any adverse cognitive outcomes in 7.5-month-old infants.

Video-oculographic Differences between Parkinson Disease and Multiple System Atrophy (P9-11.016)

<h3>Objective:</h3> With video-oculography (VOG), this study aimed to explore and compare visually-guided and self-paced volitional saccades in Parkinson’s disease (PD) and multiple system atrophy (MSA). <h3>Background:</h3> Saccades, rapid eye movements, are divided into two distinct types: reflexive and voluntary. Reflexive saccades are proceeded after a visual, auditory or somatosensory stimulus, while voluntary saccades require internally-generated drive. Each saccade is presumed to require separate neural systems. The voluntary saccades are mediated through higher centers, including frontal eye fields and basal ganglia, in addition to superior colliculus. Saccades are one of the most useful eye movements in the evaluation of the movement disorders. Voluntary saccades have been poorly investigated in PD and MSA. <h3>Design/Methods:</h3> We investigated visually guided reflexive and memory guided voluntary saccades by video-oculography in 39 PD and 15 MSA patients. There were no differences for age, sex, and UPDRS motor scores between PD and MSA patients. Two saccades were recorded sequentially, using an infrared eye tracking system (SMI, South Korea). <h3>Results:</h3> Comparison of visually-guided reflexive saccades between PD and MSA patients showed no difference in accuracy and peak velocity. In self-paced volitional saccades, PD patients produced significantly longer mean accuracy than MSA patients. Pause at the left eccentric position was consistently longer in both PD and MSA, with no statistical group difference. Volitional saccadic velocity was significantly slower than reflexive saccadic velocity in both groups. Self-paced saccadic accuracy was higher than reflexive saccadic accuracy only in PD, with significant difference. MSA patients did not show significant differences of accuracy between two saccades, although mean accuracy tended to be decreased in volitional saccades paradigm. <h3>Conclusions:</h3> In both PD and MSA patients, saccadic eye movements driven by memory-guided voluntary effort had much slower velocity, compared to visually-guided reflexive saccades. PD patients showed hypermetric volitional saccades, meanwhile MSA groups had no difference in accuracy between two saccades. <b>Disclosure:</b> Ms. Kim has nothing to disclose. Dr. Kim has nothing to disclose. Dr. Kim has nothing to disclose. Dr. Chang has nothing to disclose. Kee Duk Park has nothing to disclose. Dr. Yun has nothing to disclose.

Photoelectric Integrated Device With Dual Photodiode-Body-Biased MOSFETs Enabling Near Infrared Eye Tracking for Augmented and Virtual Realities

Aiming for eye-tracking applications, we report on a photoelectric integrated device (PID) formed by dual photodiode-body-biased MOSFETs (PD-MOS) in a differential setup. The CMOS-processed integrated device demonstrates low dark current of ~10pA, high gain of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${4}\times {10} ^{{6}}$ </tex-math></inline-formula> @940nm and 100pW/cm2, a wide dynamic range of 160dB and a noise current of 32fA/Hz <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{\text {1/2}}}$ </tex-math></inline-formula> @1kHz. It outperforms photodiode, phototransistor, avalanche photodiode and silicon photomultiplier in terms of signal to noise ratio, dynamic range, form factor, and power consumption, making it promising for eye tracking and tracing in augmented reality, virtual reality, and mixed reality applications.

Parameters of Optokinetic Nystagmus Are Influenced by the Nature of a Visual Stimulus

Studies on contrast sensitivity (CS) testing using optokinetic nystagmus (OKN) proposed adjusting the stimulus presentation duration based on its contrast, to increase the time efficiency of such measurement. Furthermore, stimulus-specific limits of the least OKN gain might reduce false negatives in OKN detection procedures. Therefore, we aimed to test the effects of various stimulus characteristics on OKN and to propose the stimulus-specific limits for the OKN gain and stimulus presentation duration. We tested the effect of contrast (C), spatial frequency (SF), and color on selected parameters of robust OKN response, namely its onset and offset time, amplitude, and gain. The right eyes of fifteen emmetropes were tracked with an infrared eye tracker during monocular observations of sinusoidal gratings moving over the horizontal plane with a velocity of (21∘/s). The available contrast levels were C: 0.5%, 2.0%, 8.2%, 16.5%, 33.0%, and 55.5% presented in a random order for ten times in all measurements of SF: 0.12, 0.25, 0.5, and 1.00 cycles per degree and grating type: luminance, red-green, and blue-yellow. This study showed a significant effect of the stimulus characteristics on the OKN onset, offset and gain. The effect of SF was insignificant in OKN amplitude; however, it indicated significance for the C and grating type. Furthermore, the OKN gain and offset limits were proposed as functions of contrast for the luminance and chromatic gratings. This study concludes the characteristics of a visual stimulus have an effect on the OKN gain and onset and offset time, yet do not affect the eye-movement amplitude considerably. Moreover, the proposed limits are expected to improve the time efficiency and eye-movement detection in OKN-based contrast sensitivity measurements.

Vergence eye movements impairments in schizophrenia and bipolar disorder

One of the most evaluated eye tracking tasks in schizophrenia (SZ) and bipolar disorder (BD) are smooth pursuit eye movements. They rely on the maintenance of slowly moving object on the fovea. While most of the studies evaluated tracking of a target that moves in the fronto-parallel plane, only two assessed vergence eye movements (VEM), which relies on the pursuit of object that moves in depth. The aim of our study was to compare VEM performance in SZ and BD. We evaluated 28 SZ patients, 32 BD patients and 25 healthy controls (HC). Participants underwent thorough optometric examination before eye tracking task. VEM were measured with the use of infrared eye tracker and dedicated vergence stimuli generator. SZ patients showed higher mean break and recovery points of fusion and shorter correct tracking time than HC. BD individuals revealed tracking accuracy deficits and higher number of saccades than HC. Compared to BD, SZ patients showed decrease of maximal convergence and divergence. Moreover, they presented tracking accuracy deficits of non-dominant eye: altered eyes positioning error during convergence and divergence gain. Exploratory analysis revealed significant gender differences between groups in terms of binocular VEM parameters. In this study we have recognized pattern of eye movement disturbances differentiating abovementioned groups. SZ patients showed decreased vergence tracking range with shorter tracking time and impaired accuracy of non-dominant eye, while BD patients showed higher number of saccades with decreased tracking accuracy. Neuroimaging studies are necessary to identify neuronal underpinnings of VEM impairments in SZ and BD.

Associations of prenatal exposure to per- and polyfluoroalkyl substances (PFAS) with measures of cognition in 7.5-month-old infants

Keywords: PFAS, mixtures, neurodevelopment Background: Per- and polyfluoroalkyl substances (PFAS) are man-made chemicals that are of health concern given their persistence in the environment and human body, and transmission to offspring during pregnancy. Studies examining the relationship between PFAS and neurodevelopment are inconclusive and largely have been conducted in older children. In the present study, we examined whether prenatal exposure to a mixture of PFAS was related to cognitive function in infancy. Methods: Pregnant participants were enrolled in the Chemicals in Our Bodies cohort and Illinois Kids Development Study, which together make up the ECHO.CA.IL cohort. Seven PFAS were previously measured in 2nd trimester maternal serum samples and were natural log transformed for analyses. Infant cognition was assessed at 7.5 months using a visual recognition memory task that tracks infant looking behavior using an infrared eye tracker. From the eye-tracking data, we calculated two measures of attention (based on infants shifting their looking between two stimuli, and the time it took them to reach cumulative looking criterion), information processing speed (based on how long infants looked at the stimuli before looking away) during the familiarization trial, and recognition memory (based on infants’ looking at novel compared to the familiar stimulus) in the test trial. Bayesian kernel machine regressions (BKMR) were used to assess joint associations between multiple PFAS and individual cognitive outcomes (N=160). Results: Unexpectedly, prenatal exposure to the PFAS mixture was modestly associated with better attention, as indicated by faster shifts between stimuli, with PFNA, PFOS, PFHxS, and PFUdA contributing the most to the overall mixture effect. Increasing exposure to the PFAS mixture was weakly associated better information processing speed and attention although credible intervals include the null value. Conclusions: Using a visual recognition memory task, we observed little evidence that prenatal PFAS exposure is associated with cognitive function.

Comparing infrared and webcam eye tracking in the Visual World Paradigm

Visual World eye tracking is a temporally fine-grained method of monitoring attention, making it a popular tool in the study of online sentence processing. Recently, while infrared eye tracking was mostly unavailable, various web-based experiment platforms have rapidly developed webcam eye tracking functionalities, which are now in urgent need of testing and evaluation. We replicated a recent Visual World study on the incremental processing of verb aspect in English using ‘out of the box’ webcam eye tracking software (jsPsych; de Leeuw, 2015) and crowdsourced participants, and fully replicated both the offline and online results of the original study. We furthermore discuss factors influencing the quality and interpretability of webcam eye tracking data, particularly with regards to temporal and spatial resolution; and conclude that remote webcam eye tracking can serve as an affordable and accessible alternative to lab-based infrared eye tracking, even for questions probing the time-course of language processing.

161-OR: Cognitive Impairment in Individuals with Post-Bariatric Hypoglycemia

Background: Post-bariatric hypoglycemia (PBH) is characterized by repeated episodes of severe hypoglycemia accompanied by neuroglycopenic signs and/or symptoms. Many individuals with PBH report chronic symptoms of cognitive impairment even when blood glucose values are not acutely low. In this study, cognitive function in individuals with PBH compared to age- and BMI-matched healthy controls (HC) was assessed using a quantitative visual paired comparison (VPC) task; a measurement validated to predict cognitive decline and Alzheimer’s disease. Methods: 20 patients with confirmed PBH (plasma glucose &amp;lt;50 mg/dL with concomitant insulin ≥3 uU/mL, other causes having been ruled out) following Roux-en-Y gastric bypass surgery were compared to 54 age- (46±vs. 50±9 yrs, p=0.05) and BMI- (31±vs. 28±4 kg/m2, p=0.07) matched HCs. Patient-reported frequency of clinically-important hypoglycemic events, defined as fingerstick or plasma glucose &amp;lt;60 mg/dL, was collected by standardized questionnaire. The VPC task, which measures cognitive function by utilizing infrared eye tracking to assess the participant’s novelty preference when presented with a series of novel and familiar images, was conducted under standardized conditions when blood glucose was in the normal range in the clinical research unit. Results: Compared to HCs, PBH patients scored 12% lower on the VPC task (0.65± 0.vs. 0.57 ±0.15, P= 0.005) . The mean VPC score in PBH patients was in the range that predicts a 22% risk of cognitive decline or Alzheimer’s disease over a 3-year period. Among PBH patients, patient-reported frequency of clinically important hypoglycemic events correlated significantly with VPC score (r=0.44, p=0.047) . Conclusions: Patients with PBH exhibit cognitive impairment when compared to age- and BMI-matched HCs and the degree of impairment correlates with the frequency of clinically important hypoglycemic events. Disclosure T.Shamloo: None. C.M.Craig: Employee; Eiger BioPharmaceuticals, Stock/Shareholder; Eiger BioPharmaceuticals. M.Snyder: Stock/Shareholder; January, Inc. T.Mclaughlin: Board Member; January, Inc., Research Support; Merck &amp; Co., Inc., Novo Nordisk, Stock/Shareholder; Eiger BioPharmaceuticals. Funding American Diabetes Association (1-19-ICTS-073) ; NIH 1U54DE02378901

Objective Infrared Eye Tracking Aids in the Identification of Concussion-Related Vision Disorders in Adolescen Ts with Persistent Post-Concussive Symptoms

Background:The visio-vestibular examination (VVE) of smooth pursuit, saccades, vestibulo-oculomotor reflex, near point of convergence (NPC), accommodative amplitude (AA), and complex tandem gait, has enhanced the physical examination of concussed individuals. The EyeBOX is a FDA-approved device for the diagnosis of concussion.Hypothesis:The goal of this investigation was to determine the diagnostic accuracy for concussion-related vision disorders of infrared eye-tracking via the EyeBOX.Methods:A cross-sectional study of 112 adolescents ages 11-18 years of age experiencing persistent post-concussion symptoms 4-12 weeks after concussion was conducted. All subjects had a clinical visio-vestibular examination (VVE) with a sports medicine physician, and a formal, comprehensive vision examination conducted by a pediatric developmental optometrist. A binocular eye tracking assessment was performed using the EyeBOX. Binocular pupil gaze positions are captured to ensure quality data acquisition and binocular movements in the X and Y axes are recorded at 500 Hz. Dynamic time series eye tracking data is acquired with 89 different metrics from eye movement in different planes recorded for each eye at 500 Hz captured over 220 seconds. From the time series data, a summary score, between 0 and 20, the BOX score, is generated.Logistic regression was used to estimate the association between each clinical VVE parameter and concussion-related vision diagnosis. Univariate and multivariate analyses were performed to determine the predictive ability of all VVE parameters to predict a concussion-related vision diagnosis. The area under the receiver-operator (ROC) curve was estimated by treating the linear predictor from the logistic regression as a continuous diagnostic parameter. A p-value is reported for the Wald test of whether a logistic regression coefficient differs from zero. Results:The clinical VVE variables had an AUC = 0.64 for tandem gait errors (p=0.06), 0.64 for monocular AA (p=0.01 for each), and 0.66 for NPC (p<0.01). A multivariable model including all nine VVE variables had predictive ability to identify concussion-related vision disorders in adolescents with persistent post-concussion symptoms with an AUC = 0.73. The BOX score alone had an AUC = 0.67 (p<0.01).Conclusions:The addition of the BOX score, a composite measure of objectively acquired eye tracking data, to the multivariable model with all nine dichotomous VVE variables added significant additional diagnostic ability (p<0.01), yielding an AUC = 0.81. The combination of a clinical visio-vestibular examination and objective infrared eye tracking has relevant diagnostic value, facilitating identification and treatment of concussion-related vision disorders.

Webcam Eye Tracking for Monitoring Visual Attention in Hypothetical Online Shopping Tasks

Online retailers are challenged to present their products in an appropriate way to attract customers’ attention. To test the impact of product presentation features on customers’ visual attention, webcam eye tracking might be an alternative to infrared eye tracking, especially in situations where face-to-face contact is difficult. The aim of this study was to examine whether webcam eye tracking is suitable for investigating the influence of certain exogenous factors on customers’ visual attention when visiting online clothing shops. For this purpose, screenshots of two websites of two well-known online clothing retailers were used as stimuli. Linear regression analyses were conducted to determine the influence of the spatial position and the presence of a human model on the percentage of participants visiting a product depiction. The results show that products presented by human models and located in the upper middle area of a website were visited by more participants. From this, we were able to derive recommendations for optimising product presentation in online clothing shops. Our results fit well with those of other studies on visual attention conducted with infrared eye tracking, suggesting that webcam eye tracking could be an alternative to infrared eye tracking, at least for similar research questions.

Contrast Sensitivity Testing in Healthy and Blurred Vision Conditions Using a Novel Optokinetic Nystagmus Live-Detection Method

PurposeThe aim of the current study was to develop and validate an automated contrast sensitivity (CS) test using a live- detection of optokinetic nystagmus (OKN) and an adaptive psychometric procedure. In addition, the study sought to replicate the known effect of defocus on CS for the OKN-based measurements in emmetropic participants.MethodsFifteen participants viewed a horizontally moving grating while their eyes were tracked with an infra-red (IR) eye-tracker. To simulate the clinical conditions of the CS measurements, the participants were stimulated monocularly as the left eye was occluded by an IR filter. The horizontal eye position was continuously analyzed for OKN responses, and the stimulus contrast was changed by an adaptive psychometric method depending on the outcome. Furthermore, the newly proposed OKN live-detection was verified against an offline analysis and an expert-observer judgement. The OKN-based CS was measured for six spatial frequencies at normal vision and three levels of defocus using spherical convex lenses.ResultsThe newly proposed OKN live-detection method showed a sufficient detection performance for implementation of adaptive procedures, and the detection rate is similar or better compared to offline detection methods. Spatial frequency and defocus had a significant effect on the OKN-based CS (P < 0.0001 for both).ConclusionsThe current study presents a novel method to measure motion CS in an automated way, combining the real-time detection of OKN and an adaptive psychometric procedure. Furthermore, the known effect of defocus on CS was successfully replicated with the newly developed tool.Translational RelevanceOKN-based CS is a novel approach to assess spatial vision, which is sensitive to subtle effects of defocus, allowing use with nonverbal patients and infants. Furthermore, the newly developed tool may improve the performance of such measurements.

Visual fixation patterns during basic facial emotion recognition and its correlation with social impairment among children with high-functioning autism spectrum disorder

Objective: To explore the visual fixation patterns during facial emotion recognition and the association between fixation duration percentage (FDP) of eye region with social impairment among high-functioning autism spectrum disorders (HFASD). Methods: Children were recruited from the Child and Adolescent Behavior Research Center of Sun Yat-sen University, Guangzhou, between July and December 2019 for case control study. A total of 42 children with HFASD and 23 age-and gender-matched typical development (TD) children were enrolled. Based on their performance during the facial emotion recognition task, HFASD children were further divided into ASD-1 group (correctly recognized both happy and fear emotions) and ASD-2 group (recognized happy emotions only). During the free viewing task, an infrared eye tracker was used to record the gazing data of children in the three groups. The social responsiveness scales (SRS) was utilized to evaluate HFASD children's social impairment, with the cutoff score of 75 to differentiate those from mild and severe social impairment. The differences of FDP among the three groups were analyzed by the Analysis of Variance (ANOVA) model. Mixed linear regression model was conducted to evaluate the associations between social impairment and FDP of eye region among HFASD children. Results: The final sample consists of 25 ASD-1 (20 males, aged (7.9±1.0) years), 17 ASD-2(14 males, aged (7.2±1.2) years), and 23 TD (12 males, aged (7.7±1.3) years) children. There were no significant differences in age and gender among three groups (F=2.05, χ²=10.08, P=0.14 and 0.07, respectively). For the happy emotion, there are significant differences in eye FDP among the three groups (TD: 0.37±0.20, ASD-1: 0.35±0.20, ASD-2: 0.47±0.24, F=3.97, P=0.02). Mixed linear regression model revealed that, adjusting for emotion, gender, age and intelligence quotient, ASD children's eye FDP negatively associates with social impairment (OR=0.15, 95%CI: 0.06-0.35, P<0.01). Conclusions: Longer FDP is associated with milder social impairment among HFASD children. HFASD children with facial emotion recognition difficulties require longer fixation to recognize happy emotions.

Phasic activity of the locus-coeruleus is not a mediator of the relationship between fitness and inhibition in college-aged adults

Aerobic fitness is consistently and robustly associated with superior performance on assessments of cognitive control. One potential mechanism underlying this phenomenon is activation of the locus-coeruleus. Specifically, individuals with greater aerobic fitness may be better able to sustain engagement in a cognitively demanding task via a superior ability to meet the metabolic demands of this neural system. Accordingly, the present investigation examined 1) the relationship between aerobic fitness and phasic activation of the locus-coeruleus (indexed using pupillometry) and 2) the potential mediating influence of locus-coeruleus activity on the relationship between aerobic fitness and cognitive task performance. Participants performed an inhibition task while their pupillary responses were measured using an infrared eye tracker. A VO2max test was then performed to determine individuals' aerobic fitness levels. Consistent with previous research, higher levels of aerobic fitness were related to shorter reaction time. However, phasic activity of the locus-coeruleus did not mediate this relationship – nor did it relate to aerobic fitness level. These results suggest that aerobic fitness does not relate to differences in locus-coeruleus activity in the context of cognitive control in college-aged adults.

Validity and reliability of horizontal measurement for head repositioning accuracy by laser

Many chronic neck pain patients experience problems with vision. These problems are possibly induced by deviations of the eye stabilization reflexes. It is not known whether these eye reflex alterations occur both in traumatic and non-traumatic neck pain patients.To investigate if the cervico-ocular reflex (COR) and the vestibulo-ocular reflex (VOR) are changed in tertiary care patients with prolonged, chronic neck pain with various origin of complaints.Cross sectional study.Ninety-one chronic neck pain patients were subdivided into three groups by origin of complaints, and compared with healthy controls. COR and VOR gains were measured with an infrared eye tracking device with the subject sitting on a rotating chair in a darkened room and with the head fixed.Neck pain patients had a higher COR gain (median 0.41, IQR 0.289) compared with healthy controls (median 0.231, IQR 0.179). The mean COR gain did not differ between the three patient groups (Whiplash Associated Disorders 0.444 (SD 0.221); traumatic 0.397 (SD0.205); non-traumatic 0.468 (SD0.236)). There was no difference in VOR gain between the groups.Chronic neck pain patients, who already received primary care, still have an elevated cervico-ocular reflex. The origin of complaints did not seem to be associated with this deviant oculomotor behavior.

Pupillary Responses Indicate Working Memory Processing Differences: Implications For Healthy And Clinical Populations

Task-evoked pupillary responses (PR) are established psychophysiological measures for neural resource allocation. During working memory tasks, pupils dilate proportional to increasing cognitive demands and constrict when demands exceed resource availability. PRs have demonstrated greater sensitivity to load-dependent processing differences in clinical populations, beyond performance accuracy, under high cognitive demands. Few studies have examined concussion history, sex, and performance accuracy effects on PRs across varying cognitive load levels. PURPOSE: To examine effects of concussion history, sex, and performance accuracy on PR in healthy individuals during a digit-span task. METHODS: Participants self-reported sex (female vs. male) and concussion history (yes vs. no), and completed a backwards digit-span task in a single testing session. A virtual reality headset with 60Hz infrared eye tracking displayed the task and recorded pupil size fluctuations. Pupil size (diameter in mm) was recorded before each trial (baseline=3sec) and following randomly presented digit sequences between 4 and 14 digits long (retention=2sec). PR was calculated as the mean size during retention, normalized to mean baseline. Accuracy was calculated as the proportion of correctly recalled digits by serial position. A mixed effects model examined concussion history, sex, and accuracy effects on PR across sequence-lengths (a priori α=0.05). RESULTS: 40 participants were included [age=21.9±2.1years; males=50%; 17 (43%) with concussion history]. There were significant effects of sex (F1,36=15.66, p<0.001) and accuracy (F1,2588=4.70, p<0.03) on overall relative PR controlling for all other model predictors and interactions. Specifically, females exhibited smaller mean PRs compared to males. Smaller mean PRs were also associated with higher average task accuracy. CONCLUSION: In our study, females exhibited smaller overall pupillary responses during a digit-span working memory task compared to males, indicating potential sex-dependent processing differences. The association between better task accuracy and smaller PRs may further support PR meauress to better inform neurocognitive processing differences in healthy and clinical populations, when demands exceed cognitive resource availability.