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Abstract Background Children with visual impairment often exhibit poor postural control. However, the effects of strabismus on oculomotor system components and its impact on balance in children are not yet fully understood. This study aims to determine the potential effects of oculomotor functions on balance skills in children with strabismus. Methods A total of 30 children aged between 6 and 10 years participated in this study. Fifteen children diagnosed with strabismus were included in the strabismus group (8.07 ± 1.33 years), and 15 healthy children without any vision problems were included in the control group (8.03 ± 1.49 years). All children underwent a comprehensive hearing evaluation, bedside neurological and balance examinations, the Pediatric Balance Scale (PBS) assessment to assess balance function, and Videonystagmography (VNG) tests to measure oculomotor function. Results In the saccade test, no significant differences were found between the groups in terms of latency, accuracy, and speed (p > 0.05). The strabismus group showed significantly lower pursuit test gains (except the left eye at 0.4 Hz) (p 0.05). The strabismus group had significantly lower scores on the 360-degree rotation task (10th item) (p = 0.027) and total PBS scores (p = 0.029). Correlation analysis revealed statistically significant negative correlations between strabismus angle and optokinetic test gains, pursuit test gains, and PBS total scores, with varying correlation strengths (p

Background: Children with visual impairment often exhibit poor postural control. However, the effects of strabismus on oculomotor system components and its impact on balance in children are not yet fully understood. This study aims to determine the potential effects of oculomotor functions on balance skills in children with strabismus. Methods: A total of 30 children aged between 6 and 10 years participated in this study. Fifteen children diagnosed with strabismus were included in the strabismus group (8.07 ± 1.33 years), and 15 healthy children without any vision problems were included in the control group (8.03 ± 1.49 years). All children underwent a comprehensive hearing evaluation, bedside neurological and balance examinations, the Pediatric Balance Scale (PBS) assessment to assess balance function, and Videonystagmography (VNG) tests to measure oculomotor function. Results: In the saccade test, no significant differences were found between the groups in terms of latency, accuracy, and speed (p > 0.05). The strabismus group showed significantly lower pursuit test gains (except the left eye at 0.4 Hz) (p < 0.05) and significantly higher asymmetries (except the right eye at 0.4 Hz) (p < 0.05). No significant difference was observed between the groups in optokinetic test gains (p > 0.05). The strabismus group had significantly lower scores on the 360-degree rotation task (10th item) (p = 0.027) and total PBS scores (p = 0.029). Correlation analysis revealed statistically significant negative correlations between strabismus angle and optokinetic test gains, pursuit test gains, and PBS total scores, with varying correlation strengths (p < 0.05 and − 0.639 < r < − 0.338). Conclusions: Strabismus adversely affects the optokinetic and pursuit systems, as well as balance in children. Furthermore, an increase in the strabismus angle is associated with greater adverse effects on these functions. The lower scores obtained in the PBS scores of the strabismus group indicate that strabismus may negatively affect balance skills in activities of daily living. Early intervention and targeted therapies should be considered to mitigate these effects and support the development of balance skills in children with strabismus. [ABSTRACT FROM AUTHOR]

Amyotrophic lateral sclerosis (ALS) can result into an incomplete locked in state (iLIS), in which communication depends on eye tracking computer devices. Oculomotor function impairments in ALS have been reported, but there is little research, particularly with respect to patients in iLIS. In the present study, we compared reflexive and executive oculomotor function by means of an eye tracking test battery between three groups: advanced ALS patients in iLIS (n = 22), patients in early to middle ALS stages (n = 44) and healthy subjects (n = 32). Patients with ALS showed significant deteriorations in oculomotor functions, with stronger impairments in iLIS. More specifically, ALS patients produced visually guided prosaccades with longer latencies and more frequent hypometria compared to healthy subjects. Longest latencies were obtained in iLIS patients, with a stronger prolongation for vertical than for horizontal prosaccades. ALS patients made more antisaccade errors and generated antisaccades with longer latencies. Smooth pursuit was also impaired in ALS. In the earlier ALS stages, bulbar onset patients presented stronger antisaccade and smooth pursuit deficits than spinal onset patients. Our findings reveal a relevant deterioration of important oculomotor functions in ALS, which increases in iLIS. It includes impairments of reflexive eye movements to loss of executive inhibitory control, indicating a progressing pathological involvement of prefrontal, midbrain and brainstem areas. The assessment of oculomotor functions may therefore provide clinically relevant bio- and progression marker, particularly in advanced ALS. [ABSTRACT FROM AUTHOR]

AbstractBlink reflex assessment has been suggested as a potential marker for sport-related concussions (SRCs) screening. However, exertion level is known to affect the blink reflex, which may affect the clinical utility of sideline screening and post-concussion monitoring. This validation study of 44 male college-aged athletes found significant differences in several blink reflex parameters between baseline and active play. In assessing the differences between mild and moderate/higher intensity, as a function of heart rate, the number of oscillations was the only significantly different parameter between the two groups. When combining the two groups (mild and moderate/higher intensity) and comparing to baseline values of the blink reflex, there were significant differences in latency, initial velocity, time to open, and lid excursions. Using baseline data, the EyeStat provides a greater understanding of its application during baseline, and exercise monitoring.

Blink reflex assessment has been suggested as a potential marker for sportrelated concussions (SRCs) screening. However, exertion level is known to affect the blink reflex, which may affect the clinical utility of sideline screening and postconcussion monitoring. This validation study of 44 male college-aged athletes found significant differences in several blink reflex parameters between baseline and active play. In assessing the differences between mild and moderate/higher intensity, as a function of heart rate, the number of oscillations was the only significantly different parameter between the two groups. When combining the two groups (mild and moderate/higher intensity) and comparing to baseline values of the blink reflex, there were significant differences in latency, initial velocity, time to open, and lid excursions. Using baseline data, the EyeStat provides a greater understanding of its application during baseline, and exercise monitoring. [ABSTRACT FROM AUTHOR]

BACKGROUND: Little is known on the peripheral and central sensory contributions to persistent dizziness and imbalance following mild traumatic brain injury (mTBI). OBJECTIVE: To identify peripheral vestibular, central integrative, and oculomotor causes for chronic symptoms following mTBI. METHODS: Individuals with chronic mTBI symptoms and healthy controls (HC) completed a battery of oculomotor, peripheral vestibular and instrumented posturography evaluations and rated subjective symptoms on validated questionnaires. We defined abnormal oculomotor, peripheral vestibular, and central sensory integration for balance measures among mTBI participants as falling outside a 10-percentile cutoff determined from HC data. A X-squared test associated the proportion of normal and abnormal responses in each group. Partial Spearman's rank correlations evaluated the relationships between chronic symptoms and measures of oculomotor, peripheral vestibular, and central function for balance control. RESULTS: The mTBI group (n = 58) had more abnormal measures of central sensory integration for balance than the HC (n = 61) group (mTBI: 41% –61%; HC: 10%, p's < 0.001), but no differences on oculomotor and peripheral vestibular function (p > 0.113). Symptom severities were negatively correlated with central sensory integration for balance scores (p's < 0.048). CONCLUSIONS: Ongoing balance complaints in people with chronic mTBI are explained more by central sensory integration dysfunction rather than peripheral vestibular or oculomotor dysfunction. [ABSTRACT FROM AUTHOR]

Background: The eponymous feature of progressive supranuclear palsy (PSP) is oculomotor impairment which is one of the relevant domains in the Movement Disorder Society diagnostic criteria. Objective: We aimed to investigate the value of specific video-oculographic parameters for the use as diagnostic markers in PSP. Methods: An analysis of video-oculography recordings of 100 PSP patients and 49 age-matched healthy control subjects was performed. Gain of smooth pursuit eye movement and latency, gain, peak eye velocity, asymmetry of downward and upward velocities of saccades as well as rate of saccadic intrusions were analyzed. Results: Vertical saccade velocity and saccadic intrusions allowed for the classification of about 70% and 56% of the patients, respectively. By combining both parameters, almost 80% of the PSP patients were covered, while vertical velocity asymmetry was observed in approximately 34%. All parameters had a specificity of above 95%. The sensitivities were lower with around 50–60% for the velocity and saccadic intrusions and only 27% for vertical asymmetry. Conclusions: In accordance with oculomotor features in the current PSP diagnostic criteria, video-oculographic assessment of vertical saccade velocity and saccadic intrusions resulted in very high specificity. Asymmetry of vertical saccade velocities, in the opposite, did not prove to be useful for diagnostic purposes. [ABSTRACT FROM AUTHOR]

Abstract Background This study aims to test response inhibition in premanifest Huntington’s disease individuals (Pre-HD), in the context of a saccadic paradigm with working memory demands and fronto-executive load as a way to measure inhibitory control deficits and impulsive behavior in Huntington’s disease (HD). Methods The oculomotor function of 15 Pre-HD and 22 Control individuals was assessed using an experimental paradigm comprising four horizontal saccadic tasks: prosaccade (PS), antisaccade (AS), 1- or 2-back memory prosaccade (MPS), and 1- or 2-back memory antisaccade (MAS). Success rate, latency, directional and timing errors were calculated for each task. A comprehensive battery of neuropsychological tests was also used to assess the overall cognitive functioning of study participants. Statistical correlations between oculomotor, clinical and cognitive measures were computed for the Pre-HD group. Results Pre-HD participants showed reduced success rate in the AS task, increased direction errors in the AS and MAS tasks and decreased latency in the MAS task when compared to Controls, despite presenting similar executive and memory scores in the conventional neuropsychological tests applied. Significant associations were identified between specific AS and MAS parameters and disease-related measures, cognitive skills and other oculomotor results of Pre-HD participants. Conclusions Our results show that oculomotor performance in premanifest Huntington’s disease deteriorates once inhibitory control, working memory and/or fronto-executive load are added to the task. A more automatic pattern of performance, including a faster response time and directionally erroneous eye movements were detected in the oculomotor behavior of the Pre-HD group—these alterations were significantly correlated with disease stage and cognitive status. Our saccadic paradigm was able to capture impulsivity and inhibitory control deficits in a group of Pre-HD individuals on average far from symptom onset, thus holding the potential to identify the earliest disease-related changes.

Abstract Introduction Oculomotor function has not been systematically studied in frontotemporal dementia (FTD) and yet may offer a simple target to monitor disease activity. Methods We assessed fixation stability, smooth pursuit, pro‐saccades, and anti‐saccades using the Eyelink 1000‐plus eye‐tracker in 19 individuals with behavioral variant FTD (bvFTD) and 22 controls. Neuroanatomical correlates were assessed using a region of interest magnetic resonance imaging (MRI) analysis. Results Measures of fixation stability were impaired in the bvFTD group compared with controls. However, performance did not differ from controls in the pro‐saccade tasks except in the vertical overlap condition. The bvFTD group performed worse in the anti‐saccade task, which correlated strongly with executive function. Neural correlates included the orbitofrontal and ventromedial prefrontal cortices and striatum for fixation stability, and the dorsolateral prefrontal and parietal cortices and striatum for anti‐saccades. Discussion Overall, oculomotor function is abnormal in bvFTD, with performance likely related to impairment of inhibitory control and executive dysfunction.

Introduction: Oculomotor function has not been systematically studied in frontotemporal dementia (FTD) and yet may offer a simple target to monitor disease activity. Methods: We assessed fixation stability, smooth pursuit, pro‐saccades, and anti‐saccades using the Eyelink 1000‐plus eye‐tracker in 19 individuals with behavioral variant FTD (bvFTD) and 22 controls. Neuroanatomical correlates were assessed using a region of interest magnetic resonance imaging (MRI) analysis. Results: Measures of fixation stability were impaired in the bvFTD group compared with controls. However, performance did not differ from controls in the pro‐saccade tasks except in the vertical overlap condition. The bvFTD group performed worse in the anti‐saccade task, which correlated strongly with executive function. Neural correlates included the orbitofrontal and ventromedial prefrontal cortices and striatum for fixation stability, and the dorsolateral prefrontal and parietal cortices and striatum for anti‐saccades. Discussion: Overall, oculomotor function is abnormal in bvFTD, with performance likely related to impairment of inhibitory control and executive dysfunction. [ABSTRACT FROM AUTHOR]

Background: Top‐down volitional command of eye movements may serve as a candidate endophenotype of ADHD, an important function underlying goal‐directed action in everyday life. In this twin study, we examined the relation between performance on a response inhibition eye‐tracking paradigm and parent‐rated ADHD traits in a population‐based twin sample. We hypothesized that altered eye movement control is associated with the severity of ADHD traits and that this association is attributable to genetic factors. Methods: A total of 640 twins (320 pairs, 50% monozygotic) aged 9–14 years) from the Child and Adolescent Twin Study in Sweden (CATSS) participated. Twins performed the antisaccade task indexing inhibitory alterations as either direction errors (following exogenous cues rather than instructions) or premature anticipatory eye movements (failure to wait for cues). We calculated the associations of eye movement control and ADHD traits using linear regression mixed‐effects models and genetic and environmental influences with multivariate twin models. Results: Premature anticipatory eye movements were positively associated with inattentive traits (β =.17; 95% CI: 0.04, 0.31), while controlling for hyperactive behaviors and other covariates. Both premature anticipatory eye movements and inattention were heritable (h2 = 0.40, 95% CI: 0.22, 0.56; h2 = 0.55; 95% CI: 0.42, 0.65; respectively), and their genetic correlation was small but statistically significant (r =.19, 95% CI: 0.02, 0.36). However, the genetic correlation did not remain significant after adjusting for covariates (age, sex, hyperactivity traits, IQ). No link was found between direction errors and ADHD traits. Conclusions: This study indicates that there is a specific, genetically influenced, relation between top‐down eye movement control and the inattentive traits typical of ADHD. [ABSTRACT FROM AUTHOR]

Background.: The existing literature on the effectiveness of interventions targeting vision, visual-perceptual impairments following acquired brain injury (ABI) is scarce and unlinked to occupational performance. Purpose.: To explore current occupational therapy practice in vision-rehabilitation among adults with ABI in Canada, and to determine the evidence-practice gaps. Methods.: An online survey was made available through the Canadian Association of Occupational Therapists (CAOT) website, and disseminated to seven public healthcare institutions in Quebec. The survey collected respondent demographic information, and the types and frequency of treatments delivered. Descriptive statistics were conducted to determine interventions' frequency. Participant comments were collected and grouped into recurring themes. Findings.: Over half (55%) of respondents regularly use evidence-based interventions when addressing visual acuity (VA) and visual field (VF) deficits, but only very few (3%) use it when dealing with oculomotor function and visual stress impairments. Implications.: Results gave a glimpse of interventions used and suggested the need for further research in vision rehabilitation. [ABSTRACT FROM AUTHOR]

Objective: To document baseline King-Devick (K-D) oculomotor function scores for male and female participants aged between 4 and 20 years old. Methods: Utilising a cross section of schools, rugby clubs and gymnastic clubs, 1936 participants (1300 male, 636 female) completed the spiral-bound K-D test for the identification of disturbed oculomotor function. Results: This study identified that overall, the baseline scores of the K-D test became faster by 1.4 (0.3 to 4.5) s per year, when compared with the previous age group in the same number of reading card groups. When comparing normative values of the original K-D validation study with the same age groups of the current cohort, participants aged 6 to 11 years recorded a faster baseline time (range 3.5 to 8.6 s), while those in the 12 to 14 years. age group recorded slower baseline times (range −3.9 to −7.9 s). Discussion: In general, there were age group differences, but not sex differences, for K-D test times in the current cohort. Analysis of single card times, across all age groups, showed changes likely due to improved reading time. Conclusion: The results support the need for individualised annual pre-injury baseline testing of the K-D test.

Background: This study aims to test response inhibition in premanifest Huntington's disease individuals (Pre-HD), in the context of a saccadic paradigm with working memory demands and fronto-executive load as a way to measure inhibitory control deficits and impulsive behavior in Huntington's disease (HD).Methods: The oculomotor function of 15 Pre-HD and 22 Control individuals was assessed using an experimental paradigm comprising four horizontal saccadic tasks: prosaccade (PS), antisaccade (AS), 1- or 2-back memory prosaccade (MPS), and 1- or 2-back memory antisaccade (MAS). Success rate, latency, directional and timing errors were calculated for each task. A comprehensive battery of neuropsychological tests was also used to assess the overall cognitive functioning of study participants. Statistical correlations between oculomotor, clinical and cognitive measures were computed for the Pre-HD group.Results: Pre-HD participants showed reduced success rate in the AS task, increased direction errors in the AS and MAS tasks and decreased latency in the MAS task when compared to Controls, despite presenting similar executive and memory scores in the conventional neuropsychological tests applied. Significant associations were identified between specific AS and MAS parameters and disease-related measures, cognitive skills and other oculomotor results of Pre-HD participants.Conclusions: Our results show that oculomotor performance in premanifest Huntington's disease deteriorates once inhibitory control, working memory and/or fronto-executive load are added to the task. A more automatic pattern of performance, including a faster response time and directionally erroneous eye movements were detected in the oculomotor behavior of the Pre-HD group-these alterations were significantly correlated with disease stage and cognitive status. Our saccadic paradigm was able to capture impulsivity and inhibitory control deficits in a group of Pre-HD individuals on average far from symptom onset, thus holding the potential to identify the earliest disease-related changes. [ABSTRACT FROM AUTHOR]

Abstract Background Rett syndrome (RTT) is a neurological disorder characterized by a broad spectrum of symptoms. Communication is a major area of difficulty. Use of eye tracking technology offers a potentially effective method of communication when underpinned by intact oculomotor function. In this study, oculomotor function was assessed using electronystagmography (ENG). However, challenges were encountered when examining individuals with RTT. Purpose To improve oculomotor examination in individuals with RTT by evaluating the challenges encountered during ENG examination. Material and methods Oculomotor function was examined in 17 girls and young women with RTT and 16 typically developing (TD) individuals using ENG. Observational analysis of both performance and results indicated that challenges in examination were mainly related to quality of attention and quality of signals. Subsequently these outcome values were explored quantitatively according to percentage looking time for attention and drift for signal quality. Results A significantly reduced level of attention and suboptimal electrode signals were evident in the RTT group when compared with the TD group for all tests except torsion swing. Conclusion The challenges in testing confirm that regular oculomotor examination should be adjusted to meet the needs of individuals with RTT. It is hypothesized that the RTT group's higher quality of attention on the torsion swing can be explained by the more forceful vestibular rather than visual-ocular stimulus operating in this test. Suggested adaptations include reducing the number of electrodes, changing the picture stimuli and bringing them closer, performing observational assessments rather than ENG, and using virtual reality goggles. Highlights • The RTT cohort show significantly reduced levels of attention on standard ENG testing. • Suboptimal electrode signals are also evident when testing the RTT group. • Regular oculomotor examination should be adjusted for individuals with RTT. • Virtual reality goggles may offer an alternative form of assessment. [ABSTRACT FROM AUTHOR]

Background: Individuals with Rett syndrome (RTT) are notoriously reliant on the use of eye gaze as a primary means of communication. Underlying an ability to communicate successfully via eye gaze is a complex matrix of requirements, with an intact oculomotor system being just one element. To date, the underlying neural and motor pathways associated with eye gaze are relatively under-researched in RTT.Purpose: This study was undertaken to plug this gap in knowledge and to further the understanding of RTT in one specific area of development and function, namely oculomotor function.Material and Methods: The eye movements of 18 girls and young women with RTT were assessed by electronystagmography (ENG). This tested their horizontal saccadic and smooth pursuit eye movements as well as optokinetic nystagmus and vestibulo-ocular reflex. Their results were compared with normative data collected from 16 typically developing children and teenagers.Results: Overall, the individuals with RTT demonstrated a range of eye movements on a par with their typically developing peers. However, there were a number of difficulties in executing the ENG testing with the RTT cohort which made quantitative analysis tricky, such as reduced motivation and attention to test materials and low-quality electrode signals.Conclusions: This study suggests that individuals with RTT have an intact oculomotor system. However, modifications should be made to the ENG assessment procedure to combat problems in testing and add strength to the results. Further investigation into these testing difficulties is warranted in order to inform such modifications. [ABSTRACT FROM AUTHOR]

Objective There is increasing evidence that the cerebellum has a role in pain processing. The present study investigates whether chronic pain patients, who are likely to have altered pain processing, exhibit signs of subtle cerebellar dysfunction. We used oculomotor tasks to assess dysfunction of the associated neuronal networks, including the cerebellum. Methods Thirty patients with chronic nonspecific spinal pain and 30 age- and sex-matched controls were enrolled. Using a head-mounted eye tracker (EyeSeeCam), eye movements were quantified during predictable and unpredictable saccade and smooth pursuit tasks in the horizontal plane. Results The initial latency and the velocity variability of smooth pursuit were significantly increased in the chronic spinal pain patients compared with controls (initial latency: 198 ± 20 vs 185 ± 11 ms, P  < 0.01; slow phase velocity standard deviation: 3.31 ± 1.02 vs 2.70 ± 0.83°/s, P  < 0.05). Moreover, the latency of predictable saccades was prolonged in patients (rightward: 161 ± 20 vs 152 ± 12 ms, P  < 0.05; leftward: 164 ± 22 vs 153 ± 18 ms, P  = 0.05). Conclusions Our results show that chronic spinal pain patients display subtle but significant oculomotor changes as compared with healthy controls. Considering the networks involved in the generation of saccades and smooth pursuit, the results would be consistent with a dysfunction of cerebellar regions, especially parts of the cerebellar hemispheres. Alternatively, they could also point toward a dysfunction in the frontal eye field and/or pontine oculomotor nuclei. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the potential utility of a self-paced saccadic eye movement as a marker of post-concussion syndrome (PCS) and monitoring the recovery from PCS. Fifty-nine persistently symptomatic participants with at least two concussions performed the self-paced saccade (SPS) task. We evaluated the relationships between the number of SPSs and 1) number of self-reported concussion symptoms, and 2) integrity of major white matter (WM) tracts (as measured by fractional anisotropy [FA] and mean diffusivity) that are directly or indirectly involved in saccadic eye movements and often affected by concussion. These tracts included the uncinate fasciculus (UF), cingulum (Cg) and its three subcomponents (subgenual, retrosplenial, and parahippocampal), superior longitudinal fasciculus, and corpus callosum. Mediation analyses were carried out to examine whether specific WM tracts (left UF and left subgenual Cg) mediated the relationship between the number of SPSs and 1) interval from last concussion or 2) total number of self-reported symptoms. The number of SPSs was negatively correlated with the total number of self-reported symptoms (r = −0.419, p = 0.026). The number of SPSs were positively correlated with FA of left UF and left Cg (r = 0.421, p = 0.013 and r = 0.452, p = 0.008; respectively). FA of the subgenual subcomponent of the left Cg partially mediated the relationship between the total number of symptoms and the number of SPSs, while FA of the left UF mediated the relationship between interval from last concussion and the number of SPSs. In conclusion, SPS testing as a fast and objective assessment may reflect symptom burden in patients with PCS. In addition, since the number of SPSs is associated with the integrity of some WM tracts, it may be useful as a diagnostic biomarker in patients with PCS. [ABSTRACT FROM AUTHOR]

Background: One common feature of neurodegenerative parkinsonism including Parkinson's disease (PD), multisystem atrophy (MSA), and progressive supranuclear palsy (PSP) is altered eye movement control. Characteristic regional structural atrophy patterns in MRI can be observed in PD, MSA, and PSP. Objective: To investigate the association between eye movement disturbances and regional brain atrophy in patients with PD, MSA, and PSP. Methods: High-resolution 3-dimensional T1-weighted MRI images and videooculographic recordings (EyeLink ®) were obtained from 39 PD, 32 PSP, and 18 MSA patients and 24 matched healthy control subjects. Automatic regional volumetric assessment was performed using atlas-based volumetry (ABV). Results: The prevalence of saccadic intrusions as a measure of inhibitory control was significantly increased in PD patients compared to controls (p < 0.001) and negatively correlated with whole brain volume, cerebral brain volume, and occipital lobe volume (p = 0.0057, p = 0.0049, and p = 0.0059, respectively; all p values are false discovery rate corrected). In MSA, smooth pursuit was disturbed by characteristic "catch-up" saccades (p < 0.001) and it was significantly correlated with cerebellar volume (p = 0.004) and pontine volume (p < 0.001). The hallmark of PSP was pathologically slowed vertical peak eye velocities (p < 0.001); the lower the peak eye velocity, the more marked midbrain atrophy (p = 0.007). Conclusions: Foci of regional atrophy correlated with disease-specific eye movement alterations in all investigated parkinsonian syndromes. Oculomotor impairment in PD, predominantly the result of executive dysfunction, was linked to cerebral atrophy. Impairment in the corresponding oculomotor pathways was associated with atrophy of pontocerebellar oculomotor structures in MSA and midbrain atrophy in PSP. [ABSTRACT FROM AUTHOR]

Context: The King-Devick (KD) test is a screening tool designed to assess cognitive visual impairments, namely saccadic rhythm, postconcussion. Test-retest reliability of the KD in a healthy adolescent population has not yet been established. Objective: To investigate the overall test-retest reliability of the KD among a sample of healthy adolescents. Additionally, we sought to determine if sex and age influenced reliability. Design: Cross-sectional study. Setting: Secondary school. Patients or Other Participants: Sixty-eight healthy adolescents, 41 boys (age=15.4 ± 1.9 years) and 27 girls (age=15.4 ± 1.9 years). Main Outcome Measure(s): Participants completed the KD (version 1) at 3 testing sessions (days 1, 30, and 45) following standard instructions. We recorded total time to complete the reading of 3 cards for each participant during each testing session. Two-way random-effects intraclass correlation coefficients (ICCs) using single measurements repeated over time and repeatability coefficients were calculated. Linear mixed models were used to determine whether differences existed at each testing time and to examine whether changes that took place among visits were different by sex or age. Results: Adolescents who completed the KD demonstrated acceptable reliability (ICC = 0.81; 95% confidence interval = 0.73, 0.87); however, the repeatability coefficient was large (±8.7± seconds). The sample demonstrated improvements between visits 1 and 2 (mean ± standard error = 4.3 ± 0.5 seconds, P , .001) and between visits 2 and 3 (2.4 ± 0.5 seconds, P , .001) for a total improvement of ±.9 seconds over 3 tests. No significant visit-by-sex or visit-by-age interactions were observed. Conclusions: Despite the ICC being clinically acceptable, providers using the KD test for serial assessment of concussion in adolescents should be cautious in interpreting the results due to a large learning effect. Incorporating multiple measures can ensure accurate detection of sport concussion. [ABSTRACT FROM AUTHOR]

Binocular vision is the most important visual cue for spatial orientation in many sports. In this study, we investigated how binocular vision was influenced by an eye training program that may be used to improve individual's oculomotor function. The experiment involved twenty-four female student athletes from team ball sports (soccer, basketball, handball). After an initial testing session, 12 participants were randomly allocated to the experimental group. Optometric investigation which included synoptophore testing and a test of dissociated horizontal phoria based on the Maddox method was performed three times: before the experiment, after eight weeks of eye training (3 times a week for 20 minutes), and four weeks after the experiment was terminated. Eye exercise methodology was based on orthoptic, sport and psychological aspects of performance. The phoria screening examination showed that exophoria was the most frequent disorder of binocular vision. Low fusional vergence range was also observed. Following the training period, 3 of the 6 oculomotor variables improved. The greatest effect was observed in near dissociated phoria (χ2=14.56, p=0.001 for the right eye; χ2=14.757, p=0.001 for the left eye) and fusional convergence (χ2=8.522, p=0.014). The results of the retention test conducted four weeks after the experiment confirmed the effectiveness of the vision training program. The results of the study suggest that binocular functions are trainable and can be improved by means of appropriate visual training. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine whether repetitive exposure to low-level blasts during military breacher training produces acute and cumulative damage to the ocular tissues or visual system. The effects of low-level blast exposure on high-contrast visual acuity, contrast sensitivity, oculomotor function, color vision, visual field (VF), pupillary light reflex, corneal endothelial cell density (ECD), macular thickness, retinal nerve fiber layer thickness, and cup-to-disc ratio were assessed using a battery of standard clinical ophthalmic tests administered 10 times over a 2-year period. Data from nine male breacher instructors (Cadre) were compared with data from four male breacher engineers (Control). The Cadre group showed higher vertical deviation at near than the Control group over time. The VF mean deviation on the left eye tended to be worse in the Cadre group throughout the study, suggesting a decrease in VF sensitivity (Cadre: -0.20 +/- 0.15 dB; Control: 1.05 +/- 0.15 dB; p = 0.03). The Cadre group had a reduced ECD (right eye: Cadre 2,478 cells/mm² vs Control 2,808 cells/ mm², p = 0.02; left eye: Cadre 2,562 cells/mm² vs Control 2,892 cells/mm², p = 0.03). These results suggest that even low-level primary blast has the potential to produce occult eye injury. [ABSTRACT FROM AUTHOR]

Stimulation of the accommodation system results in a response in the vergence system via accommodative vergence cross-link interactions, and stimulation of the vergence system results in an accommodation response via vergence accommodation cross-link interactions. Cross-link interactions are necessary in order to ensure simultaneous responses in the accommodation and vergence systems. The crosslink interactions are represented most comprehensively by the response AC/A (accommodative vergence) and CA/C (vergence accommodation) ratios, although the stimulus AC/A ratio is measured clinically, and the stimulus CA/C ratio is seldom measured in clinical practice. The present study aims to quantify both stimulus and response AC/A and CA/C ratios in a binocularly normal population, and determine the relationship between them. 25 Subjects (mean ± SD age 21.0 ± 1.9 years) were recruited from the university population. A significant linear relationship was found between the stimulus and response ratios, for both AC/A ( r 2 = 0.96, p < 0.001) and CA/C ratios ( r 2 = 0.40, p < 0.05). Good agreement was found between the stimulus and response AC/A ratios (95% CI −0.06 to 0.24 MA/D). Stimulus and response CA/C ratios are linearly related. Stimulus CA/C ratios were higher than response ratios at low values, and lower than response ratios at high values (95% CI −0.46 to 0.42 D/MA). Agreement between stimulus and response CA/C ratios is poorer than that found for AC/A ratios due to increased variability in vergence responses when viewing the Gaussian blurred target. This study has shown that more work is needed to refine the methodology of CA/C ratio measurement. [ABSTRACT FROM AUTHOR]

Traumatic brain injury (TBI) and posttraumatic stress disorder (PTSD) are signature injuries of the Iraq and Afghanistan conflicts. The conditions can be comorbid and have overlapping signs and symptoms, making it difficult to diagnose and treat each. TBI is associated with numerous changes in vision function, but vision problems secondary to PTSD have not been documented. To address this shortcoming, we reviewed the medical records of 100 patients with a history of TBI, noting PTSD diagnoses, visual symptoms, vision function abnormalities, and medications with visual side effects. Forty-one patients had PTSD and 59 did not. High rates of binocular vision and oculomotor function deficits were measured in patients with a history of TBI, but no significant differences between patients with or without PTSD were evident. However, compared to patients without PTSD, patients with PTSD had more self-reported visual symptoms in all four assessments and the complaint rates were significantly higher for light sensitivity and reading problems. Together, these findings may be beneficial in understanding vision problems in patients with TBI and PTSD as comorbid conditions compared with those with TBI alone. [ABSTRACT FROM AUTHOR]

Small vessel cerebrovascular disease (SVCD) is one of the most frequent vessel disorders in the aged brain. Among the spectrum of neurological disturbances related to SVCD, oculomotor dysfunction is a not well understood symptom- in particular, it remains unclear whether vascular lesion load in specific brain regions affects oculomotor function independent of cognitive decline in SVCD patients or whether the effect of higher brain function deficits prevails. In this study, we examined a cohort of 25 SVCD patients and 19 healthy controls using video-oculographic eye movement recording in a laboratory environment, computer-based MRI assessment of white matter lesion load (WMLL), assessment of extrapyramidal motor deficits, and psychometric testing. In comparison to controls, the mean WMLL of patients was significantly larger than in controls. With respect to eye movement control, patients performed significantly worse than controls in almost all aspects of oculomotion. Likewise, patients showed a significantly worse performance in all but one of the neuropsychological tests. Oculomotor deficits in SVCD correlated with the patients' cognitive dysfunctioning while there was only weak evidence for a direct effect of WMLL on eye movement control. In conclusion, oculomotor impairment in SVCD seems to be mainly contingent upon cognitive deterioration in SVCD while WMLL might have only a minor specific effect upon oculomotor pathways. [ABSTRACT FROM AUTHOR]

The prevalence of oculomotor dysfunctions associated with blast-induced mild traumatic brain injury (mTBI) in warfighters has increased as a consequence of recent conflicts. This study evaluated the effectiveness of computerized oculomotor vision screening (COVS) in a military population. Oculomotor functions were assessed with COVS and by conventional methods in 20 U.S. military personnel with and 20 without mTBI. The validity of COVS was determined by Pearson correlation and Bland-Altman method or the kappa coefficient. The repeatability of the COVS was assessed with the coefficient of repeatability or the kappa coefficient. The results showed that COVS had high sensitivity and specificity for screening near oculomotor functions. Overall, the COVS showed excellent validity and repeatability for assessing near lateral and vertical phorias, Worth 4 Dot, and fixation, as well as pursuit and saccadic eye movements. Despite the strong Pearson correlation, the Bland-Altman analysis identified minor to moderate discrepancies for both positive and negative fusional vergence and their associated recovery as well as for the monocular accommodative facility measurements. This study demonstrated that non-eye-care professionals may be able to use the COVS as a tool to efficiently screen oculomotor functions in a military population with or without mTBI. [ABSTRACT FROM AUTHOR]

Background: The basal ganglia (BG) are thought to play an important role in the control of eye movements. Accordingly, the broad variety of subtle oculomotor alterations that has been described in Parkinson's disease (PD) are generally attributed to the dysfunction of the BG dopaminergic system. However, the present study suggest that dopamine substitution is much less effective in improving oculomotor performance than it is in restoring skeletomotor abilities. Methods: We investigated reactive, visually guided saccades (RS), smooth pursuit eye movements (SPEM), and rapidly left-right alternating voluntary gaze shifts (AVGS) by video-oculography in 34 PD patients receiving oral dopaminergic medication (PD-DA), 14 patients with deep brain stimulation of the nucleus subthalamicus (DBSSTN), and 23 control subjects (CTL);In addition, we performed a thorough review of recent literature according therapeuthic effects on oculomotor performance in PD by switching deep brain stimulation off and on in the PDDBS patients, we achieved swift changes between their therapeutic states without the delays of dopamine withdrawal. In addition, participants underwent neuropsychological testing. Results: Patients exhibited the well known deficits such as increased saccade latency, reduced SPEM gain, and reduced frequency and amplitude of AVGS. Across patients none of the investigated oculomotor parameters correlated with UPDRS III whereas there was a negative correlation between SPEM gain and susceptibility to interference (Stroop score). Of the observed deficiencies, DBS-STN slightly improved AVGS frequency but neither AVGS amplitude nor SPEM or RS performance. Conclusions: We conclude that the impairment of SPEM in PD results from a cortical, conceivably nondopaminergic dysfunction, whereas patients' difficulty to rapidly execute AVGS might be related to their BG dysfunction. [ABSTRACT FROM AUTHOR]

Abstract: Oculomotor abnormalities can be observed in all Parkinsonian syndromes (PS). Nevertheless, due to the considerable overlap of oculomotor pathology in Parkinsonism, oculomotor changes are not generally considered to contribute substantially to the differential diagnosis of PS. Here we review the characteristics of oculomotor disturbances in the major PS, we provide a survey of the current concepts of the underlying neural physiology of oculomotor control and a summary of the major recording techniques for eye movements. The main focus of this review is to outline the subtle differences between apparently similar oculomotor alterations in Parkinson’s disease (PD) and atypical neurodegenerative PS that can contribute to the early differential diagnosis of these entities. [Copyright &y& Elsevier]

Abstract: Mice are excellent subjects for use of genetic-manipulation techniques to study the basis of pathological and normal physiology and behavior; however behavioral analyses of associated phenotypes is often limited. To improve the accuracy and specificity of repeated measurements of vestibular function, we developed a miniaturized, contact-lens scleral search coil to measure mouse eye movements. We describe the physical attributes and document its functionality by measuring vestibuloocular responses in normal mice. This coil should greatly improve the sensitivity and documentation of vestibular dysfunction in mouse models of pathology and dysfunction while allowing screening of significant numbers of subjects. [ABSTRACT FROM AUTHOR]

Abstract: Individuals with Parkinson''s disease (PD) show marked impairments in their ability to generate self-initiated, or “voluntary”, saccadic eye movements. Investigations of visually guided, or “reflexive”, saccades have, on the other hand, produced inconclusive results with studies showing response times (RTs) in persons with PD that are slower, faster, or indistinguishable from those of controls. We performed a meta-analysis to establish whether there are consistent effects of PD on the metrics of visually guided saccades. Combining results across 47 studies we found that reflexive saccades are overall initiated more slowly in persons with PD than in controls, however, this analysis also revealed considerable heterogeneity across studies. Step-wise meta-regression, using eleven potential predictors, subsequently showed that differences in mean RT between controls and persons with PD may arise due to aspects of experimental design. In particular, mean target eccentricity was shown to impact substantially on RTs such that persons with PD predictably initiate saccades faster than controls at small target eccentricities, while responding more slowly for large target eccentricities. Changes in eye-tracking and display equipment over the period covered by the review were also found to have impacted on the pattern of results obtained. We conclude that a, previously unsuspected, eccentricity effect could explain why the saccadic eye movements of persons with PD are sometimes found to be “hyper-reflexive” compared to controls, and suggest that this effect may arise due to PD-induced changes in both peripheral perceptual processing and in central executive mechanisms involving the basal ganglia. [Copyright &y& Elsevier]

Abstract: Background: A subgroup of individuals with vestibular dysfunction and visual motion hypersensitivity (VMH) become dizzy and imbalanced in response to movement of the visual environment. The purpose of this study was to investigate ocular fixational stability during gaze on a target, with and without visual background movement. Binocular vision functions were also examined as possible contributory factors to the dizziness and imbalance. Methods: Twenty-four individuals with VMH, 20 with vestibular disorders without VMH and 20 healthy subjects were tested. Assignment to the experimental group was by symptoms of VMH. Outcome measures included electro-oculogram recordings of horizontal fixation and blink. Four clinical binocular vision functions were also tested. The Dizziness Handicap Inventory was used to assess the level of dizziness. Conclusion: Subjects with VMH made significantly more refixational eye movements and had higher levels of dizziness than those in the other 2 diagnostic groups. There were abnormalities of binocular function in both the VMH and vestibular dysfunction groups compared with the control group. Individuals with VMH were unable to maintain stable gaze and inhibit eye movements to background motion. The large number of subjects with diagnosis of fluctuating vestibular function in the VMH group compared with the vestibular dysfunction group may indicate that VMH is a maladaptation of the system. [Copyright &y& Elsevier]

Abstract: Background: Oculomotor control has been implicated as a factor when reading is poor, but few studies exist for adolescents. Methods: The saccadic eye movement efficiency of 684 ninth grade students, identified as poor readers in 5 California high schools, was quantified using the Developmental Eye Movement test. Frequency distributions were produced from scores on vertical and horizontal components, and gender and test-retest factors were considered during analysis. Results: Vertical times were within 1 standard deviation of normal for eighth grade. However, horizontal (saccadic) times were typical of grade 3, and the average number of errors on the horizontal test was typical of grade 2. Boys and girls performed similarly. Results of retests showed slightly improved horizontal times and fewer errors, but the grade level equivalents remained dramatically low. Overall, fewer than 10% of students scored above the 50th percentile for eighth grade. Conclusion: The results indicate that poor readers in high school may be at high risk for poor saccadic tracking skill. [Copyright &y& Elsevier]

Study Design. A consecutive, prospective, blinded clinical study. Objectives. To determine if the smooth pursuit neck torsion (SPNT) test can differ between WAD and alternative diagnoses. Summary of Background Data. About ten percent of whiplash injured individuals in the western world develop chronic conditions called whiplash associated disorders (WAD). Many medicolegal conflicts have been caused by the lack of objective findings. However, preliminary studies have demonstrated the efficacy of the smooth pursuit neck torsion (SPNT) test. Methods. A study group of 160 patients with WAD and a control group of 122 patients with non-traumatic neck pain (cervical spondylosis (52), cervical dizziness (47) and fibromyalgia (24)) were chosen for a validity study. The SPNT test is a smooth pursuit eye movement test. The subjects are placed in a neutral position, and then they turn 45 degrees to the right and to the left. The difference between the average gain in neutral and torsion positions is the test parameter. Results. The validity of the SPNT test (using the 99.5th percentile) as a specific test for diagnosing WAD was: sensitivity 72%, specificity 92%, predictive value as a positive test 92%, predictive value as a negative test 71%. The odd ratio was 28.6. Conclusions. This study supports the view that the smooth pursuit neck torsion test is useful for diagnosing whiplash associated disorders. [ABSTRACT FROM PUBLISHER]