Ocular Fixation Research Articles

Different Evaluation Strategies of Oncological CT Examinations with Regard to Professional Experience: A Clinical Study Using Eye-tracking.

Contrast-enhanced CT is the standard imaging technique in oncological objectives. Rates of missed pathologies depend on work experience of the respective radiologists. Thus the aim of this study is to analyze the eye movements of professionals while reading CT images in order to evaluate whether the eye-fixation patterns and search strategies of experienced radiologists could explain higher detection rates of pathologies and whether such patterns can be learned.Anonymized images of 10 patients were presented to three medical students and six radiologists with different levels of work experience. During image analysis, ocular fixation positions were recorded using an eye-tracking software tool. The CT scans were analyzed retrospectively, considering the individual course of disease with the issue of successful detection of all pathologies. Visual attention and dwell time of ocular fixation on clinically important abnormalities or areas with pathological findings, general search patterns, and time efficiency were assessed. For statistical analysis, interobserver variability and accuracy of lesion detection were evaluated taking into account individual experience.The results revealed that observer sensitivity depends on work experience due to a more systematic order of inspection and a well-known course of disease, e.g. in case of metastatic spread. The areas of missed pathologies mostly included secondary findings. Inexperienced readers changed the stratification considerably more often and required more time for reporting or detecting pathologies.Our results suggest that experienced radiological physicians reduce their amount of missed findings by looking more systematically at images and by applying a more targeted inspection of clinically important regions. · CT interpretation by radiology residents is faster and less error-prone compared to postgraduate residents. · systematic image analysis is trainable. · engrams tend to be acquired through experience. · Kluge S, Schülke C, Ites HC et al. Different Evaluation Strategies of Oncological CT Examinations with Regard to Professional Experience: A Clinical Study Using Eye-tracking. Fortschr Röntgenstr 2024; DOI 10.1055/a-2452-2180.

Analysis of the Effect of Preoperative Eye Position Fixation Training in Patients With Pterygium: A Randomized Controlled Trial.

This study evaluated the effect of preoperative ocular fixation training on patients undergoing pterygium surgery. Before pterygium excision, patients were trained to perform eye position fixation training, which is beneficial for surgeons performing microsurgery. The study analysed the effectiveness of preoperative eye position fixation training in patients with pterygium by randomised controlled experimental design. The number of occurrences of self-turning, operation time, self-rating depression scale scores and self-rating anxiety scale scores of the experimental group (EG) were lower than those of the control group (CG). The recurrence rate and the incidence of conjunctival tear and conjunctival suture loosening in the EG were significantly lower than those in the CG. The use of eye fixation training prior to pterygium surgery can facilitate the activities of the surgeon, reduce the operation time, reduce the occurrence of complications and reduce the recurrence rate after the operation. Eye fixation training is worthy of application in patients with pterygium.

Evaluation of recognition memory through oculomotorius behavior in Alzheimer disease.

INTRODUCTION: The study of ocular movements in patients with Alzheimer disease is an useful tool to evaluate recognition memory. METHODS: assessment of this specific type of explicit memory in 15 individuals diagnosed with Alzheimer disease and 15 controls. The parameters of ocular fixation were examined using the Eye-Tracking Tobii Tx300 through Pair-wised ranking with the paradigm novel object recognition. RESULTS: People with Alzheimer disease present difficulties in the recognition of previously presented stimulus when the latency of presentation of the familiarization and the test period is longer than two minutes. DISCUSSION: The analysis of oculomotorius behavior can simplify the evaluation of recognition memory without appealing to verbal report and the visual paired comparison task. This contributes to the comprehension of the relationship among spatial attention, working memory and episodic memory.

Can ocular fixations modulate the perception of a bistable logo?

Bistable logos accept two different interpretations, where each interpretation can be conditioned by the area of the image that is being observed. Thus, ocular fixations can affect their final perception. To determine if the eye fixation areas influence the perception, 20 volunteers observed a bistable logo in front of a fixed eye-tracker, reference Tobii T-120. The results indicate that the reported percepts are related to ocular fixation areas. It is concluded that there are areas that affect the identification of the possible percepts of the bistable logo, which leads to essential considerations for graphic designers to optimize graphic brand communication.

What can entropy metrics tell us about the characteristics of ocular fixation trajectories?

In this study, we provide a detailed analysis of entropy measures calculated for fixation eye movement trajectories from the three different datasets. We employed six key metrics (Fuzzy, Increment, Sample, Gridded Distribution, Phase, and Spectral Entropies). We calculate these six metrics on three sets of fixations: (1) fixations from the GazeCom dataset, (2) fixations from what we refer to as the "Lund" dataset, and (3) fixations from our own research laboratory ("OK Lab" dataset). For each entropy measure, for each dataset, we closely examined the 36 fixations with the highest entropy and the 36 fixations with the lowest entropy. From this, it was clear that the nature of the information from our entropy metrics depended on which dataset was evaluated. These entropy metrics found various types of misclassified fixations in the GazeCom dataset. Two entropy metrics also detected fixation with substantial linear drift. For the Lund dataset, the only finding was that low spectral entropy was associated with what we call "bumpy" fixations. These are fixations with low-frequency oscillations. For the OK Lab dataset, three entropies found fixations with high-frequency noise which probably represent ocular microtremor. In this dataset, one entropy found fixations with linear drift. The between-dataset results are discussed in terms of the number of fixations in each dataset, the different eye movement stimuli employed, and the method of eye movement classification.

Drivers' performance assessment approaching pedestrian crossings through the analysis of the speed and perceptive data recorded during on-field tests

Pedestrian fatalities in road accidents represent one of the biggest causes of death in the world despite the great efforts that have been made to decrease the involvement of vulnerable road users in road accidents. Literature analysis revealed the presence of several studies aimed at investigating the phenomenon and proposing strategies to improve pedestrian safety, but this is still not enough to considerably reduce the number of pedestrians killed on the road.In this context, with the aim to take a step forward in the topic, this paper describes a naturalistic driving assessment carried out in Firenze aimed at evaluating the effect of different pedestrian crossing configurations on the drivers' behavior, especially concerning the reduction of the speeding phenomenon approaching a pedestrian crossing. The experiment was conducted on a section of an urban collector road within the Firenze suburban area. Crucially, over the past few years, different traffic calming interventions have been implemented along this street. Among the different traffic calming countermeasures, both the presence of a traffic light and trapezoidal deflection have been considered to assess their effect on drivers' behavior, also with reference to specific aspects related to the drivers’ perception. During the experiment, thirty-six users drove their own vehicles along the street, encountering different pedestrian crossing configurations. During the driving speed, deceleration and ocular fixation were recorded.This study shows the difference in drivers' behavior in response to different traffic calming countermeasures. It demonstrates also that the raised pedestrian crossing caused a significant effect on reducing the speed approaching a pedestrian crossing. Moreover, it is observed that, when perceptive countermeasures are present, the drivers’ behavior changes only if the pedestrian crossing configuration is perceived in foveal vision; suggesting that the correct identification of the configuration is crucial to implement a congruent and safe driving behavior.

Navigation guided removal of fragmented chopstick in orbit

A 47 year old man fell and got a chopstick stuck in his upper left eyelid. The patient presented with decreased visual acuity, upper eyelid closure injury, ptosis, and ocular fixation.

Quantification of Parkinsonian unilateral involvement from ocular fixational patterns using a deep video representation

PurposeLateralisation of motor symptoms is a prevalent characteristic of Parkinson’s disease (PD). Hence, unilateral involvement is crucial for personalized treatments and measuring therapy effectiveness. Nonetheless, most motor symptoms, including lateralization, are mainly evident at advanced stages of the disease. Recently, ocular fixation instability emerged as a promising PD biomarker with a high sensitivity to discriminate PD. We hypothesize that unilateral involvement can be recovered from the assessment and quantification of PD-related ocular abnormalities.MethodsThis method proposes a computer-based strategy to quantify PD lateralization from ocular fixation patterns. The method follows a markerless strategy fed by slices with spatiotemporal eye movement information. A deep convolutional model was used to discriminate between PD and a control population. Additionally, model prediction probabilities were analyzed to select the dominant eye associated with unilateral involvement.ResultsThe proposed approach reports an average accuracy of 91.92% classifying PD. Interestingly, using the dominant side, the approach achieves an average PD prediction probability of 93.3% (95% CI: [91.61,95.07]), evidencing capabilities to capture the most affected side. Besides, the reported results strongly correlate with the disease, even for patients categorized at early stages. A low-dimensional projection tool was used to support the classification results by finding a 2d space that eases the discrimination among classes.ConclusionsThe strategy is sensitive to detecting and classifying PD fixational patterns and determining the side with major impairments. This approach may be a potential tool to support the characterization of the disease and as an alternative to defining personalized treatments.

MHealth technology identifies visual impairment in young children.

mHealth technology identifies visual impairment in young children.

Detection of visuomotor dysfunction in mild traumatic brain injury using binocular retinal polarization scanning

ABSTRACT Objective The head and intraocular trauma tool (HITT) is a portable, binocular retinal polarization scanner (RPS) that detects ocular fixation with high precision to assess visuomotor function. We conducted a pilot evaluation of a prototype binocular RPS device to evaluate alterations in fixation stability, binocularity (convergence), and saccadic latency after mild traumatic brain injury (mTBI). Methods Two groups were studied prospectively: (1) single observation study of mTBI patients in a hospital ER (n = 7) and age-matched controls (n = 43); (2) high-school athletes preseason (n = 28), after sports-related mTBI (n = 3), and at season end (n = 5). Subjects were asked to fixate on an internal target and track randomly presented peripheral and central targets as fixation was assessed using binocular RPS. Results There were clinically and statistically significant alterations in the hospital ER group after mTBI, including a decrease in fixation stability (54.6% in patents vs 90.2% in controls, p = 0.014) and binocularity (28.7% in patients vs 86.6% in controls; p = 0.004). Similar trends, not statistically significant, were observed in saccadic latency in the hospital ER group as well as in the injured high school athletes. Conclusion The HITT device shows promise as an objective, noninvasive method for assessment of the impact of mTBI on visuomotor function. Additional studies with larger patient populations are required to evaluate efficacy for clinical use.

Exploratory evaluation of an eye-tracking system in patients with advanced spinal muscular atrophy type I receiving nusinersen.

ObjectiveThis study evaluated the feasibility of a matching-pair test using eye-tracking technology to assess nusinersen effectiveness in patients with advanced spinal muscular atrophy (SMA) type I.MethodsThis prospective, observational study enrolled patients with 5q-SMA type I who had lost gross motor function. Three different levels of matching-pair tests were conducted using the eye-gaze system (My Tobii; TobiiDynavox Inc.) at baseline, and after 9 and 24 weeks of nusinersen treatment. The primary endpoint was the change from baseline in matching-pair test scores and response times (i.e., the time to answer matching-pair test) at 24 weeks from baseline. Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND), Pediatric Quality of Life inventory for patients with Neuromuscular Disease (PedsQL-NM) and Numerical Rating Scale (NRS) scores were also assessed as secondary endpoints. Analysis of ocular fixation was performed as an additional analysis. This study was registered at https://www.umin.ac.jp/ctr/ (UMIN000033935).ResultsSeven patients (one male, six female) aged 5–21 years (median 11 years) were enrolled; all patients were bedridden and six patients were ventilated. All seven patients were able to conduct level 1 matching-pair tests at each assessment; five patients were also able to conduct levels 2 and 3. Two patients (those with the highest CHOP-INTEND scores) were able to complete all tests correctly within 60 s. There was a non-significant trend toward improvement in CHOP-INTEND, PedsQL-NM, and NRS scores over the 6-month period. There were no significant differences in the number of actions, errors, correct answers, or response times between baseline and Week 9 or 24 at any level. However, the result of an additional analysis suggests that detection of eye movement would be useful to evaluate for advanced SMA.ConclusionsEye-tracking systems are possibly feasible for the assessment of treatment efficacy in patients with advanced SMA type I.

Effect of ocular fixation on positional nystagmus in BPPV patients

Objective The quantitative suppression rate of positional nystagmus (PN) by ocular fixation (OF) is unknown. This study aims to analyse the effect of OF on the slow phase velocity (SPV) of PN during diagnostic positional manoeuvres (DPMs) with videonystagmography in patients with benign paroxysmal positional vertigo (BPPV). Design DPMs were performed on 58 patients with BPPV, 33 (56.9%) of whom were women. OF was initiated when PN was most evident, and recording was continued. The mean SPV of three consecutive nystagmus before (F0) and after (F1) OF initiation was calculated. The rate of suppression of PN by OF was found in percent with the formula (F0 – F1) x 100/F0. Study Sample 58 patients were included in this study. Results The mean age was 56.1 ± 11.2 (range 27–76). F0 and F1 values were calculated as 5.742 ± 5.589 and 1.948 ± 3.424 degrees/second, respectively (p < 0.001). The rate of suppression of PN by OF was found to be 66.1%. Conclusions OF significantly suppresses PN during DPMs in BPPV patients. Elimination of OF during DPMs is important for accurate diagnosis.

Eye Movement Abnormalities in Amyotrophic Lateral Sclerosis.

It is generally believed that eye movements are completely spared in amyotrophic lateral sclerosis (ALS). Although a series of eye movement abnormalities has been recognized in recent years, the findings are highly controversial, and bulbar disabilities should be considered in relation to eye movement abnormalities. The present study aimed to determine whether eye movement abnormalities are present in ALS and, if so, to investigate their characteristics and their association with bulbar disability in ALS patients. A total of 60 patients and 30 controls were recruited and underwent the standardized evaluations of the oculomotor system using videonystagmography. Square-wave jerks (OR: 16.20, 95% CI: 3.50–74.95, p < 0.001) and abnormal cogwheeling during smooth pursuit (OR: 14.04, 95% CI: 3.00–65.75, p = 0.001) were more frequently observed in ALS patients than in the control subjects. In subgroup analyses, square-wave jerks (OR: 26.51, 95% CI: 2.83–248.05, p = 0.004) and abnormal cogwheeling during smooth pursuit (OR: 6.56, 95% CI: 1.19–36.16, p = 0.031) were found to be more common in ALS patients with bulbar involvement (n = 44) than in those without bulbar involvement (n = 16). There were no significant differences in the investigated eye movement parameters between bulbar-onset (n = 12) and spinal-onset patients (n = 48). ALS patients showed a range of eye movement abnormalities, affecting mainly the ocular fixation and smooth pursuit systems. Our pioneering study indicates that the region of involvement could better indicate the pathophysiological essence of the abnormalities than the type of onset pattern in ALS. Eye movement abnormalities may be potential clinical markers for objectively evaluating upper brainstem or supratentorial cerebral lesion neurodegeneration in ALS.

Quiet Eye as a Mechanism for Table Tennis Performance under Fatigue and Complexity

QE is the final ocular fixation that precedes critical athletic movements and that enables athletes to gather relevant information and organize their subsequent movement. Although little is known about the factors sustaining performance in table tennis, to date there has been no investigation to assess QE as a contributor to table tennis performance. Furthermore, there is limited research regarding the influence on QE of factors that are known to impact performance, such as task complexity and fatigue. In a within-subjects experimental design, we manipulated fatigue (high vs low) and task complexity (high vs low). Eleven elite table tennis players (mage =14.72 years, mexperience = 7.27 years) underwent each of the four resulting conditions. Athletes made longer QE before hit versus missed shots (p <.001, η2p = .795) and QE and performance decreased under fatigue (p = 0.02, η2 p = .628; p = .002, η2 p = .62), but we did not detect a significant effect of complexity on QE (p = .352, η2 p = .087). This study is one of the first to show that QE sustains performance in a dynamic sport, that is table tennis, and that QE is affected by fatigue.

Influence of radial optic flow stimulation on static postural balance in Parkinson's disease: A preliminary study.

The role of optic flow in the control of balance in persons with Parkinson's disease (PD) has yet to be studied. Since basal ganglia are understood to have a role in controlling ocular fixation, we have hypothesized that persons with PD would exhibit impaired performance in fixation tasks, i.e., altered postural balance due to the possible relationships between postural disorders and visual perception. The aim of this preliminary study was to investigate how people affected by PD respond to optic flow stimuli presented with radial expanding motion, with the intention to see how the stimulation of different retinal portions may alter the static postural sway. We measured the body sway using center of pressure parameters recorded from two force platforms during the presentation of the foveal, peripheral and full field radial optic flow stimuli. Persons with PD had different visual responses in terms of fixational eye movement characteristics, with greater postural alteration in the sway area and in the medio-lateral direction than the age-matched control group. Balance impairment in the medio-lateral oscillation is often observed in persons with atypical Parkinsonism, but not in Parkinson's disease. Persons with PD are more dependent on visual feedback with respect to age-matched control subjects, and this could be due to their impaired peripheral kinesthetic feedback. Visual stimulation of standing posture would provide reliable signs in the differential diagnosis of Parkinsonism.

Cerebellar signals drive motor adjustments and visual perceptual changes during forward and backward adaptation of reactive saccades.

Saccadic adaptation ($SA$) is a cerebellar-dependent learning of motor commands ($MC$), which aims at preserving saccade accuracy. Since $SA$ alters visual localization during fixation and even more so across saccades, it could also involve changes of target and/or saccade visuospatial representations, the latter ($CDv$) resulting from a motor-to-visual transformation (forward dynamics model) of the corollary discharge of the $MC$. In the present study, we investigated if, in addition to its established role in adaptive adjustment of $MC$, the cerebellum could contribute to the adaptation-associated perceptual changes. Transfer of backward and forward adaptation to spatial perceptual performance (during ocular fixation and trans-saccadically) was assessed in eight cerebellar patients and eight healthy volunteers. In healthy participants, both types of $SA$ altered $MC$ as well as internal representations of the saccade target and of the saccadic eye displacement. In patients, adaptation-related adjustments of $MC$ and adaptation transfer to localization were strongly reduced relative to healthy participants, unraveling abnormal adaptation-related changes of target and $CDv$. Importantly, the estimated changes of $CDv$ were totally abolished following forward session but mainly preserved in backward session, suggesting that an internal model ensuring trans-saccadic localization could be located in the adaptation-related cerebellar networks or in downstream networks, respectively.

When the going gets tough, what happens to quiet eye? The role of time pressure and performance pressure during basketball free throws

In aiming sport contexts, the quiet eye (QE) - the final ocular fixation before movement initiation - is a crucial perceptual-cognitive skill. Indeed, an extended QE permits athletes to achieve high performances, aiding optimal attentional control, particularly in situations in which athletes are "under pressure." Such situations are common in sport, especially when time runs out, and even just a few points can mean the difference between victory and defeat. Although QE has been widely investigated across several sports and tasks, no previous studies have considered both the role of time pressure and performance pressure on QE. The current study aimed to comprehend the effect of tough sport situations on QE characteristics. Accordingly, we tested basketball players (competitive-élites and semi-élites) in free throw trials, manipulating both the time available to perform the task and the relevance of the performance. The results showed that time pressure and performance pressure impaired QE characteristics, regardless of expertise levels. Also, time pressure led to a decrease in free throw accuracy. Interestingly, the match between task demands and the ability to cope seemed to play a role on QE, especially in the competitive-élite players, with negative QE characteristics (short and late) when task demands exceeded the ability to cope. These findings suggest that QE research and QE training protocols should account for time pressure, performance pressure, and the players' perceived ability to cope with the requested task.

A-81 Neuropsychological Profile of Child with Spinocerebellar Ataxia, Type 29

Abstract Objective Spinocerebellar ataxia 29 (SCA29) is a rare autosomal dominant disorder resulting in infantile-onset hypertonia, gross motor delay and cognitive impairment. SCA29 causes cerebellar dysfunction and atrophy manifested by poor hand coordination, instability of gait, impaired articulation, poor hand-eye coordination, language delay, and a wide legged, unsteady walk. Slow improvement across childhood is common, but the limited available research suggests significant clinical heterogeneity among individuals diagnosed with SCA29. We report the case of a six-year-old first grade girl to highlight the cognitive profile of SCA29 and determine its consistency with the literature. Methods Full neuropsychological evaluation was conducted, including examination of overall cognitive ability, academic achievement, and behavior. Results The patient demonstrated delayed cognitive and motor skills, slow processing, reduced reading fluency, and weak reading comprehension. Impaired verbal comprehension and limited fund of knowledge was seen. Working memory and visual spatial ability were relative individual strengths, though normatively weak. Untimed and non-motor academic skills were well below peers. Performances met criteria for ADHD and Language Disorder. Conclusion Six-year-old girl with SCA29 with expected motor difficulties including gross motor delay, hypotonia, ataxia, poor ocular fixation evidenced global impairments with expected weakness with verbal comprehension and receptive language skills. This is consistent with the findings in the SCA29 literature. Comorbid diagnoses of ADHD and Language Disorder were present. Given clinical heterogeneity, this case serves to expand existing knowledge on case variability, and adds the consideration of wider comorbidities in this rare condition.

Stroke Prediction Based on the Spontaneous Nystagmus Suppression Test in Dizzy Patients: A Diagnostic Accuracy Study.

ObjectiveFailure of fixation suppression of spontaneous nystagmus is sometimes seen in patients with vestibular strokes involving the cerebellum or brainstem; however, the accuracy of this test for the discrimination between peripheral and central causes in patients with an acute vestibular syndrome (AVS) is unknown.MethodsPatients with AVS were screened and recruited (convenience sample) as part of a prospective cross-sectional study in the emergency department between 2015 and 2020. All patients received neuroimaging, which served as a reference standard. We recorded fixation suppression with video-oculography (VOG) for forward, right, and left gaze. The ocular fixation index (OFI) and the spontaneous nystagmus slow velocity reduction was calculated.ResultsWe screened 1,646 patients reporting dizziness in the emergency department and tested for spontaneous nystagmus in 148 patients with AVS. We analyzed 56 patients with a diagnosed acute unilateral vestibulopathy (vestibular neuritis) and 28 patients with a confirmed stroke. There was a complete nystagmus fixation suppression in 49.5% of patients with AVS, in 40% of patients with vestibular neuritis, and in 62.5% of patients with vestibular strokes. OFI scores had no predictive value for detecting strokes; however, a nystagmus reduction of less than 2 °/s showed a high accuracy of 76.9% (confidence interval 0.59–0.89) with a sensitivity of 62.2% and specificity of 84.8% in detecting strokes.ConclusionsThe presence of fixation suppression does not rule out a central lesion. The magnitude of suppression was lower compared to patients with vestibular neuritis. The nystagmus suppression test predicts vestibular strokes accurately provided that eye movements are recorded with VOG.Classification of EvidenceThis study provides Class II evidence that in patients with an AVS, decreased fixation suppression recorded with VOG occurred more often in stroke (76.9%) than in vestibular neuritis (37.8%).

Interocular Suppression in Primary Visual Cortex in Strabismus.

People with strabismus acquired during childhood do not experience diplopia (double vision). To investigate how perception of the duplicate image is suppressed, we raised two male monkeys with alternating exotropia by disinserting the medial rectus muscle in each eye at age four weeks. Once the animals were mature, they were brought to the laboratory and trained to fixate a small spot while recordings were made in primary visual cortex (V1). Drifting gratings were presented to the receptive fields of 500 single neurons for eight interleaved conditions: (1) right eye monocular; (2) left eye monocular; (3) right eye's field, right eye fixating; (4) right eye's field, left eye fixating; (5) left eye's field, right eye fixating; (6) left eye's field, left eye fixating; (7) both eyes' fields, right eye fixating; (8) both eyes' fields, left eye fixating. As expected, ocular dominance histograms showed a monocular bias compared with normal animals, but many cells could still be driven via both eyes. Overall, neuronal responses were not affected by switches in ocular fixation. Individual neurons exhibited binocular interactions, but mean population indices indicated no net interocular suppression or facilitation. Even neurons located in cortex with reduced cytochrome oxidase (CO) activity, representing portions of the nasal visual field where perception is suppressed during binocular viewing, showed no net inhibition. These data indicate that V1 neurons do not appear to reflect strabismic suppression and therefore the elimination of diplopia is likely to be mediated at a higher cortical level.SIGNIFICANCE STATEMENT In patients with strabismus, images fall on non-corresponding points in the two retinas. Only one image is perceived, because signals emanating from the other eye that convey the duplicate image are suppressed. The benefit is that diplopia is prevented, but the penalty is that the visual feedback required to adjust eye muscle tone to realign the globes is eliminated. Here, we report the first electrophysiological recordings from the primary visual cortex (V1) in awake monkeys raised with strabismus. The experiments were designed to reveal how perception of double images is avoided.