Horizontal Saccades Research Articles

Changes in saccadic eye movement and smooth pursuit gain in patients with acquired comitant esotropia after strabismus surgery.

This study investigates the change in horizontal saccadic eye movement and smooth pursuit in patients with acquired comitant esotropia (ACE), before and after strabismus surgery. The horizontal saccades and pursuit in 11 patients with ACE were recorded using a video eye-tracker under binocular viewing before and after strabismus surgery. Participants were instructed to fixate on the new target as rapidly as possible when it randomly appeared at either 18.3° rightward or 18.3° leftward. For smooth pursuit, participants were asked to track, as accurately as possible, a step-ramp target moving at ±6.1°/s. The asymmetry of adduction-abduction and the binocular coordination in gains of saccade and pursuit were compared between the pre- and post-surgical data. The asymmetry of adduction-abduction saccade gain in each eye after surgery tended to be smaller than that before surgery. The binocular coordination of saccade showed significant improvement after surgery in only the non-dominant eye direction. Adduction-abduction asymmetry in the smooth pursuit gain in each eye after surgery tended to be smaller than before surgery. After surgery, the binocular coordination of pursuit was improved significantly in both directions. In patients with ACE, binocular coordination of saccade and smooth pursuit was poor. Binocular coordination of saccade and pursuit seems to be improved due to the improvement in ocular deviation angle and binocular visual function after surgery.

Investigation of Camera-Free Eye-Tracking Glasses Compared to a Video-Based System.

Technological advances in eye-tracking have resulted in lightweight, portable solutions that are capable of capturing eye movements beyond laboratory settings. Eye-tracking devices have typically relied on heavier, video-based systems to detect pupil and corneal reflections. Advances in mobile eye-tracking technology could facilitate research and its application in ecological settings; more traditional laboratory research methods are able to be modified and transferred to real-world scenarios. One recent technology, the AdHawk MindLink, introduced a novel camera-free system embedded in typical eyeglass frames. This paper evaluates the AdHawk MindLink by comparing the eye-tracking recordings with a research "gold standard", the EyeLink II. By concurrently capturing data from both eyes, we compare the capability of each eye tracker to quantify metrics from fixation, saccade, and smooth pursuit tasks-typical elements in eye movement research-across a sample of 13 adults. The MindLink system was capable of capturing fixation stability within a radius of less than 0.5∘, estimating horizontal saccade amplitudes with an accuracy of 0.04∘± 2.3∘, vertical saccade amplitudes with an accuracy of 0.32∘± 2.3∘, and smooth pursuit speeds with an accuracy of 0.5 to 3∘s, depending on the pursuit speed. While the performance of the MindLink system in measuring fixation stability, saccade amplitude, and smooth pursuit eye movements were slightly inferior to the video-based system, MindLink provides sufficient gaze-tracking capabilities for dynamic settings and experiments.

Clustering eye-movement data uncovers students’ strategies for coordinating equations and diagrams of vector fields

AbstractIn mathematics education, students are repeatedly confronted with the tasks of interpreting and relating different representations. In particular, switching between equations and diagrams plays a major role in learning mathematical procedures and solving mathematical problems. In this article, we investigate a rather unexplored topic with precisely such requirements—that is, vector fields. In our study, we first presented a series of multiple-choice tasks to 147 introductory university students at the beginning of their studies and recorded students’ eye movements while they matched vector field diagrams and equations. Thereafter, students had to solve a similar coordination task on paper and justify their reasoning. Two cluster analyses were performed including (i) transition and fixation data on diagrams and options (Model 1), and (ii) additionally the number of horizontal and vertical saccades on the diagram (Model 2). In both models, two clusters emerge—with Model 1 distinguishing behaviors related to representational mapping and Model 2 additionally differentiating students according to representation-specific demands. Model 2 leads to a better distinction between the groups in terms of different performance indicators (test score, response confidence, and spatial ability) which also transfers to another task format. We conclude that vertical and horizontal saccades reflect executive actions of perception when approaching vector field coordination tasks. Thus, we recommend targeted interventions for mathematics lessons; these lessons must focus on a visual handling of the vector field diagram. Further, we infer that students’ difficulties can be attributed to covariational reasoning, thereby indicating the need for further investigations. From a methodological perspective, we reflect on the triangulation of eye-tracking and verbal data in (multiple-choice) assessment scenarios.

Brain FDG-PET correlates of saccadic disorders in early PSP.

New diagnostic criteria of Progressive Supranuclear Palsy (PSP) have highlighted the interest of Eye Movement Records (EMR) at the early stage of the disease. To investigate the metabolic brain correlates of ocular motor dysfunction using [18F] Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) in early PSP. Retrospective observational descriptive study on longitudinal data with patients who underwent EMR and FDG-PET at the stage of suggestive and possible PSP according to Movement Disorders Society criteria. Longitudinal follow-up enables to confirm diagnosis of probable PSP. Using the Statistical Parametric Mapping software, we performed whole-brain voxel-based correlations between oculomotor variables and FDG-PET metabolism. Thirty-seven patients with early PSP who fulfilled criteria of probable PSP during the follow-up were included. Decrease in the gain of vertical saccades correlated with reduced metabolism in Superior Colliculi (SC). We also found a positive correlation between mean velocity of horizontal saccades and SC metabolism as well as dorsal nuclei in the pons. Finally, increase in horizontal saccades latencies correlated with decrease of posterior parietal metabolism. These findings suggest the early involvement of SC in saccadic dysfunction in the course of PSP.

A-48 Comparative Analysis of Adolescents With a Sport-Related Concussion Versus Non-Sport-Related Concussion During Initial Visit

Abstract [Outstanding Trainee Award Winner] Purpose To investigate differences in pre-injury risk factors and clinical outcomes in adolescents with a Sport-Related Concussion (SRC) versus non-Sport-Related Concussion (non-SRC). Methods Participants (n=136, aged 10-18) presented to a specialty concussion clinic 2-30 (M=9.25) days post-injury. They completed a clinical interview with a trained clinician and were administered the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT), Post-Concussion Symptom Scale (PCSS), Concussion Clinical Profile Screening (CP Screen), Vestibular/Ocular-Motor Screening (VOMS), Screen for Child Related Anxiety Disorders - Child Version (SCARED-C), and the Generalized Anxiety Disorder Assessment (GAD-7). Data analyses utilized independent sample t-tests, chi-square tests, and descriptive statistics to compare clinical outcomes of both groups during initial visit. Alpha was set to p<.05 for all analyses. Results Adolescents with non-SRC took longer to seek specialty concussion care, were majority female, and were older than the SRC group. Non-SRC participants also reported a higher rate of migraine, depression, and anxiety history (i.e., SCARED-C Panic Disorder, SCARED-C Generalized Anxiety Disorder, and SCARED-C Anxiety Disorder). Additionally, non-SRC participants reported more symptoms on the PCSS Total score, and on most VOMS items, including Smooth Pursuits, Horizontal and Vertical Saccades, Horizontal and Vertical Vestibular-Ocular Reflex, Visual Motion Sensitivity, as well as VOMS Total. Non-SRC group also reported higher post-injury anxiety scores (i.e., GAD-7). All findings were below the p-value of .05. Conclusions The study findings suggest that mechanism of injury and individual risk factors play a significant role in determining the clinical presentation of a concussion in an SRC and non-SRC adolescent population.

A-51 EYE-SYNC Saccade Outcomes and Health/Demographic Factors in CFL Athletes

Abstract Purpose Examine the relationship between demographic and health factors, and oculomotor functioning during baseline testing in professional Canadian Football League (CFL) athletes. Methods 428 male athletes participated in baseline concussion testing. Athletes ranged in age from 21 to 40 years (M=26.44, SD=2.87) and reported a history of 0, 1, or 2+ sport-related concussions (SRCs). All athlete participants completed the Head Check questions of demographics and medical history, and the EYE-SYNC saccade test to explore how the presence of a history of concussions, Attention-Deficit/Hyperactivity Disorder (ADHD), Learning Disability (LD), age, and post-exertion influenced baseline measures of oculomotor functioning using the EYE-SYNC saccade outcomes of accuracy and precision. Results Correlations revealed no significant relationships between combined vertical and horizontal saccade outcomes and the demographic/health variables (p>05). Independent t-tests indicated no significant differences in mean saccade performance between athletes with and without ADHD and/or LD (p>.05). A three-way multiple analysis of variance, run with age group and four saccade outcomes (LeftAccuracyXY, LeftPrecisionXY, RightAccuracyXY, RightPrecisionXY), showed no main effect of age group on the combined saccade outcomes F(8, 844)=.91, p=.50. Finally, a one-way repeated measures analysis of variance also revealed no significant differences from pre- to post-exertion assessments, F(4, 56)=.41, p=.80. Conclusions The oculomotor functioning of CFL athletes at baseline does not appear to be influenced by a history of concussion, ADHD, LD, age, or physical exertion. This information may help professionals with their clinical decision-making regarding SRC diagnosis.

Visual Development in a Patient with Infantile-Onset Saccade Initiation Delay

Congenital ocular motor apraxia (COMA), also known as infantile-onset saccade initiation delay (ISID), is characterized by the inability to initiate volitional horizontal saccades. This five-month-old girl showed constant rapid movements to right or left one week after birth. After four months, she began thrusting her head from left to right when following target objects. She was diagnosed with COMA/ISID. At 4 years of age, head thrust became less evident. She first uttered meaningful words at 5 years of age, and spoke in sentences by 6 years of age. At 6 years of age, visual acuity was 1.0 in both eyes at 1 m. Head thrust disappeared at almost 6 years of age. She could not start crawling and sustaining a sitting position due to hypotonia. Clinicians should be aware of visual development in COMA/ISID and should look for them during the assessment of these children.

上眼瞼向き眼振・小脳萎縮など認めたParkinson病の 1 例

To the best of our knowledge, upbeat nystagmus (UBN) has not been reported before in patients with Parkinson's disease (PD). There are also very few reports of cerebellar atrophy in patients with PD. A-60-year-old woman with a 10-year history of PD visited our hospital for deep brain stimulation therapy for her camptocormia. Neurological examination revealed not only the core signs of PD (rigidity, resting tremor, postural instability), but also UBN. 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy revealed markedly diminished uptake of MIBG, strongly supporting the clinical diagnosis of PD. Brain MRI revealed prominent cerebellar atrophy, while the brainstem was preserved. ENG showed that the UBN was observed at the primary eye position and enhanced during upward gaze in the light, but not during downward gaze. In addition to UBN, several other abnormal ENG findings were also observed, including horizontal gaze-evoked nystagmus and rebound nystagmus. Secondly, both horizontal and vertical pursuits were disturbed and horizontal OKN was poorly induced. Lastly, the horizontal saccade was relatively hypometric, while the upward saccades were slight hypermetric. Although the pathogenesis of UBN in this patient still remains unclear, UBN is known to be mainly caused by dysfunction of the velocity-to-position integrator caused by pontomedullary lesions or pontomesencephalic lesions. Alternatively, cerebellar control over this integrator is presumably disrupted by lesions in the cerebellum itself or lesions in the cerebellar neural circuits. As for the pathogenesis of UBN in our case, pontomedullary lesion was first suspected, because, besides the abovementioned ENG findings, most cases of UBN reported in the literature are caused by medullary lesions, including lesions of both the medial vestibular and prepositus hypoglossi nuclei, which play an important role as the velocity-to-position integrator. In addition, dysfunction of the vestibular cerebellum was also suspected as a cause, judging from the cerebellar atrophy and other abnormal ENG findings. In conclusion, it is necessary to consider dysfunction of the vestibular cerebellum as a cause of abnormal eye movements in PD, not to mention dysfunction of the brainstem.

Contraversive Ocular Tilt Reaction, Body Lateropulsion and Gaze-Evoked Nystagmus After Inferior Cerebellar Peduncle and Dentate Nucleus Stroke

Contraversive Ocular Tilt Reaction, Body Lateropulsion and Gaze-Evoked Nystagmus After Inferior Cerebellar Peduncle and Dentate Nucleus Stroke

Spatial and Temporal Abnormalities of Spontaneous Fixational Saccades and Their Correlates With Positive and Cognitive Symptoms in Schizophrenia.

Visual fixation is a dynamic process, with the spontaneous occurrence of microsaccades and macrosaccades. These fixational saccades are sensitive to the structural and functional alterations of the cortical-subcortical-cerebellar circuit. Given that dysfunctional cortical-subcortical-cerebellar circuit contributes to cognitive and behavioral impairments in schizophrenia, we hypothesized that patients with schizophrenia would exhibit abnormal fixational saccades and these abnormalities would be associated with the clinical manifestations. Saccades were recorded from 140 drug-naïve patients with first-episode schizophrenia and 160 age-matched healthy controls during ten separate trials of 6-second steady fixations. Positive and negative symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). Cognition was assessed using the Measurement and Treatment Research to Improve Cognition in Schizophrenia Consensus Cognitive Battery (MCCB). Patients with schizophrenia exhibited fixational saccades more vertically than controls, which was reflected in more vertical saccades with angles around 90° and a greater vertical shift of horizontal saccades with angles around 0° in patients. The fixational saccades, especially horizontal saccades, showed longer durations, faster peak velocities, and larger amplitudes in patients. Furthermore, the greater vertical shift of horizontal saccades was associated with higher PANSS total and positive symptom scores in patients, and the longer duration of horizontal saccades was associated with lower MCCB neurocognitive composite, attention/vigilance, and speed of processing scores. Finally, based solely on these fixational eye movements, a K-nearest neighbors model classified patients with an accuracy of 85%. Conclusions: Our results reveal spatial and temporal abnormalities of fixational saccades and suggest fixational saccades as a promising biomarker for cognitive and positive symptoms and for diagnosis of schizophrenia.

The influence of scene tilt on saccade directions is amplitude dependent

When exploring a visual scene, humans make more saccades in the horizontal direction than any other direction. While many have shown that the horizontal saccade bias rotates in response to scene tilt, it is unclear whether this effect depends on saccade amplitude. We addressed this question by examining the effect of image tilt on the saccade direction distributions recorded during freely viewing natural scenes. Participants (n = 20) viewed scenes tilted at −30°, 0°, and 30°. Saccade distributions during free viewing rotated by an angle of 12.1° ± 6.7° (t(19) = 8.04, p < 0.001) in the direction of the image tilt. When we partitioned the saccades according to their amplitude we found that small amplitude saccades occurred most in the horizontal direction while large amplitude saccades were more oriented to the scene tilt (p < 0.001). To further study the characteristics of small saccades and how they are affected by scene tilt, we looked at the effect of image tilt on small fixational saccades made while fixating a central target amidst a larger scene and found that fixational saccade distributions did not rotate with scene tilt (−0.3° ±1.7° degrees; t(19) = −0.8, p = 0.39). These results suggest a combined effect of two reference frames in saccade generation: one egocentric reference frame that dominates for small saccades, biases them horizontally, and may be common for different tasks, and another allocentric reference frame that biases larger saccades along the orientation of an image during free viewing.

Eye movement study in essential tremor patients and its clinical correlates.

Essential tremor (ET) encompasses a wide spectrum of motor and non-motor features. Eye movement abnormalities were first reported two decades ago as an atypical finding in ET. Today, a growing number of publications about eye movement abnormalities in neurodegenerative diseases have helped understand their pathophysiology and the basis of their phenotypic variability. Thus, addressing such aspect in ET may disentangle, based on the oculomotor network abnormalities, the dysfunctional brain pathways in ET. In this study, we aimed to describe neurophysiological eye movement abnormalities in ET and their clinical correlates in terms of cognition and other associated clinical signs. We conducted a cross-sectional study in a tertiary neurology referral center including consecutive ET patients and cognitively normal healthy controls (HC) matched for age and sex. The study protocol included the assessment of voluntary horizontal saccades, smooth pursuit, anti-saccades and saccadic intrusions. We assessed the associated motor signs, cognitive functions and the presence of rapid eye movement disorder (RBD). Sixty-two ET patients and 66 HC were enrolled in the study. Eye movement examination showed significant abnormalities in comparison with HC (46.7% vs 20%, p = 0.002). Prolonged saccadic latency (38.7%, p = 0.033) and altered smooth pursuit (38.7%, p = 0.033) were the most common abnormalities in ET patients. Anti-saccadic errors (16% vs 0% in HC, p = 0.034) correlated with the presence of rigidity (p = 0.046), bradykinesia (p = 0.001), cognitive dysfunction (p = 0.006), executive dysfunction (p = 0.0002), apraxia (p = 0.0001), altered verbal fluency (p = 0.013) and altered backward digit span (p = 0.045) along with the presence of RBD (p = 0.035). Square-wave jerks (11.5% vs 0% in HC, p = 0.0024) correlated with rest tremor. A distinctive phenotype of ET could emerge out of this study characterized by anti-saccadic errors and a sub-cortical cognitive profile, consecutive to the disruption of the cerebello-thalamo-cortical loop. Patients with anti-saccadic errors could be cognitively vulnerable and in need of a close monitoring of their cognitive efficiency during the disease's progression. They may as well convert to Parkinson disease if they present with parkinsonism, RBD and square-wave jerks and require, consequently, a close observation of their motor progression.

The Saccade Main Sequence in Patients With Retinitis Pigmentosa and Advanced Age-Related Macular Degeneration.

Most eye-movement studies in patients with visual field defects have examined the strategies that patients use while exploring a visual scene, but they have not investigated saccade kinematics. In healthy vision, saccade trajectories follow the remarkably stereotyped "main sequence": saccade duration increases linearly with saccade amplitude; peak velocity also increases linearly for small amplitudes, but approaches a saturation limit for large amplitudes. Recent theories propose that these relationships reflect the brain's attempt to optimize vision when planning eye movements. Therefore, in patients with bilateral retinal damage, saccadic behavior might differ to optimize vision under the constraints imposed by the visual field defects. We compared saccadic behavior of patients with central vision loss, due to age-related macular degeneration (AMD), and patients with peripheral vision loss, due to retinitis pigmentosa (RP), to that of controls with normal vision (NV) using a horizontal saccade task. Both patient groups demonstrated deficits in saccade reaction times and target localization behavior, as well as altered saccade kinematics. Saccades were generally slower and the shape of the velocity profiles were often atypical, especially in the patients with RP. In the patients with AMD, the changes were far less dramatic. For both groups, saccade kinematics were affected most when the target was in the subjects' blind field. We conclude that defects of the central and peripheral retina have distinct effects on the saccade main sequence, and that visual inputs play an important role in planning the kinematics of a saccade.

Eye-tracking measures as indicators for a local vs. global view of data

Comparing data distributions is a fundamental activity in statistics and a motivating learning opportunity in schools to initiate statistical thinking. Research has shown that many students tend to perceive a data distribution as a collection of individual values rather than as a conceptual entity that has certain features such as center, spread, and shape. These difficulties are reflected in students’ tendency to focus on local details of the distribution (so-called local view of data) instead of referring to differences between the distributions as a whole (so-called global view of data). While many authors refer to school students’ conceptions and difficulties related to their view of data, there is, to the best of our knowledge, no empirical study that investigated their actual viewing behavior (local vs. global) when comparing distributions. The central assumption of this study is that specific eye-tracking measures constitute indicators for the perceiving and processing of local vs. global distributional features. For this purpose, hypotheses for differences in certain eye-tracking measures (fixation count, saccade amplitude, and saccade direction) between students with a local and global view of data were theoretically derived and empirically investigated using a methodological combination of eye-tracking and stimulated recall interviews. We analyzed data of 25 sixth-grade students who each completed four items on distributional comparisons. The results showed strong positive inter-item correlations for all eye-tracking measures, indicating high internal consistency in participants’ gaze behavior across all items. Based on the analysis of the eye-tracking stimulated recall interviews, we split our sample into those students who perceived and processed global features in half or more of the items (global view) and those below that threshold (local view). In line with our theoretically derived hypotheses, students with a global compared to a local view of data had on average significantly fewer fixations, longer saccade amplitudes, and a higher relative number of horizontal saccades. These results suggest that eye-tracking can assist in identifying students’ conceptions and difficulties related to a local vs. global view of data. Implications for school practice and further research are discussed.

Loss of torsional quick eye movements during head roll in progressive supranuclear palsy: anew diagnostic marker.

Even though impaired horizontal and vertical saccades are well-known features of progressive supranuclear palsy (PSP), abnormalities of torsional quick phases of eye movements have not been defined in PSP and other Parkinsonian syndromes. This study aims to determine the diagnostic value of decreased torsional quick phases during head oscillations in the roll plane in patients with PSP. Using video-oculography, we recorded the head and eye motion during passive head oscillations in the roll plane and determined the decrease of torsional quick phases in patients with PSP (n = 13) in comparison to normal controls (n = 13) and those with multiple system atrophy (MSA, n = 17)or idiopathic Parkinson's disease (PD, n = 6). Torsional quick phases were absent during the torsional vestibulo-ocular reflex (VOR) in 78.6% (11/13) of the patients with PSP, but only in 11.8% (2/17) of those with MSA and none with idiopathic PD or of normal controls (Chi-square tests, p < 0.001) while gains of the torsional VOR did not differ among the groups (Chi-square tests, p > 0.05). Furthermore, the torsional quick phases were smaller even when observed in patients with PSP. Loss of torsional quick phases is an early biological marker for diagnosis of PSP, and may be ascribed to degeneration of the rostral interstitial nucleus of the medial longitudinal fasciculus that contains the burst neurons for torsional as well as vertical saccades.

Ear-EEG sensitivity modeling for neural sources and ocular artifacts.

The ear-EEG has emerged as a promising candidate for real-world wearable brain monitoring. While experimental studies have validated several applications of ear-EEG, the source-sensor relationship for neural sources from across the brain surface has not yet been established. In addition, modeling of the ear-EEG sensitivity to sources of artifacts is still missing. Through volume conductor modeling, the sensitivity of various configurations of ear-EEG is established for a range of neural sources, in addition to ocular artifact sources for the blink, vertical saccade, and horizontal saccade eye movements. Results conclusively support the introduction of ear-EEG into conventional EEG paradigms for monitoring neural activity that originates from within the temporal lobes, while also revealing the extent to which ear-EEG can be used for sources further away from these regions. The use of ear-EEG in scenarios prone to ocular artifacts is also supported, through the demonstration of proportional scaling of artifacts and neural signals in various configurations of ear-EEG. The results from this study can be used to support both existing and prospective experimental ear-EEG studies and applications in the context of sensitivity to both neural sources and ocular artifacts.

A New Immersive Rehabilitation Therapy (MoveR) Improves More Than Classical Visual Training Visual Perceptual Skills in Dyslexic Children.

In this study, we wonder how to compare the improvement in visual perceptual skills (by using the test of visual perceptual skills, TVPS) in children with dyslexia after two visual training types (a new immersive rehabilitation therapy called MoveR, and the classical vision therapy). Thirty-nine children with dyslexia were enrolled in the study. They were split into two groups (G1 and G2) matched in IQ (intelligence quotient), sex, and age. Children of the group G1 underwent to MoveR training while children of the group G2 underwent to visual training. TVPS scores of four subtests were assessed twice before and 6 months after the two different types of training (MoveR or visual). MoveR training is an immersive therapy to reinforce visual discrimination, visual attention, saccadic/vergence system and spatial orientation. Visual therapy is based by training different types of eyes movements (horizontal, vertical and oblique pursuits and saccades, convergence and divergence movements), reading task and some exercise for improving eyes-head coordination. Each training type lasted 30 min a day, five days a week, for two weeks. Before training, the TVPS scores of the four subtests measured were statistically similar for both groups of children with dyslexia (G1 and G2). After training, both group of children (G1 and G2) improved the TVPS score of the four subtests assessed; however, such improvement reached significance in G1 only. We conclude that MoveR training could be a more useful tool than classical visual training to improve visual perceptual abilities in dyslexic children. Follow up studies on a larger number of dyslexic children will be necessary in order to explore whether such improvement persists over time and its eventual implication in reading or other classroom's activities.

Binocular, accommodative and oculomotor alterations in multiple sclerosis

AbstractMultiple sclerosis (MS) is an acquired demyelinating and inflammatory neurodegenerative disease affecting the central nervous system (CNS). Clinical and subclinical ocular disturbances occur in almost all patients with MS. Among them, oculomotor, accommodative and binocular alterations have been reported in MS. Our research group has conducted a complete analysis of the visual and oculomotor function in several researches with MS patients conducted in the last 4 years, obtaining a characterization of some visual aspects of the patient with MS. Concerning the binocular function, several alterations have been detected in MS patients, with divergence at near distance and stereopsis the most affected parameters. Likewise, MS patients with previous optic neuritis present worse binocular vision. Symptomatology compatible with convergence insufficiency measured with the CISS (Convergence Insufficiency Symptom Survey) is frequently reported by MS patients, but not supported by signs that show clear trend to esophoria at near. This discrepancy between the signs and symptoms could be due to the peculiarities of the CISS questionnaire, including items that are also related to the cognitive function and other ocular abnormalities.Oculomotor alterations have been reported also in patients with multiple sclerosis (MS), especially saccadic dysfunctions. The indirect analysis of horizontal saccades with the Developmental Eye Movement (DEM) and King‐Devick tests shows that are affected by MS, with more level of alteration if there has been a previous episode of optic neuritis. Similar findings have been also reported by other authors using objective eye tracking or video‐oculographic systems. Specifically, the most reported saccadic alterations in advanced MS and clinically isolated syndrome (CIS) are saccadic dysmetry (41.7%) and impaired smooth pursuit (42.3%), which relates to prolonged saccadic latency, no matter if they have suffered or not optic neuritis or internuclear ophthalmoplegia (INO). An increase in saccadic latency has been even found in children with MS. Saccadic initiation time (SI time) and average inter‐saccadic intervals (ISI) are also higher in patients with MS. Furthermore, the first cause of acquired pendular nystagmus is MS.Finally, macular sensitivity measured by microperimetry has been found to be altered in MS patients, especially in eyes with previous optic neuritis. Likewise, a fixational instability characterized also my microperimetry is present in MS patients with optic neuritis, with more increase of the vertical axis of the fixation area than of the horizontal. The ratio of the disease also affects the patient fixation pattern.

Ocular myasthenia gravis saccades as a measure of extraocular muscle function.

It is important to understand the pathophysiology of ocular myasthenia gravis (OMG) to improve treatment. To use modern video-oculography to characterise saccadic eye movements in patients with OMG, including anti-AChR, anti-MuSK, anti-LRP4, and seronegative OMG. In total, 21 patients with OMG and five age-matched healthy control subjects underwent video-oculography. Participants performed a sequence of horizontal saccades (3 minutes each) at ±5°, ± 10°, and ±20°, followed by 3 minutes of saccades directed at randomly presented targets at ±5°, ± 10°, and ±15°. We recorded the direction, amplitude, duration, peak, and average velocity of each saccade for each task for each participant. Saccadic amplitude, duration, and average velocity were all lower in OMG patients than in control subjects (p<0.021). Saccadic amplitude and velocity decreased over time, but this decrease was similar in OMG patients and control subjects. Fixation drift and ocular disparity tended to be greater in OMG patients than in control subjects. Saccadic intrusions occurred more frequently in OMG patients than in control subjects (p<0.001). No significant effects of time or group by time on fixation drift or ocular disparity were found. Saccadic velocities in OMG patients differed from those in normal control subjects, which suggests that OMG affects fast-twitch fibres, although fast-twitch fibres were still able to generate "twitch" or "quiver" movements in the presence of even severe ophthalmoplegia. Slow-twitch muscle fibres involved in gaze holding were also affected, accounting for increased fixation drift following saccades. Our objective finding of increased fixation drift and a larger number of saccadic intrusions mirror our anecdotal experience of patients with OMG who report significant diplopia despite minimal ophthalmoplegia on examination. Such microsaccades may be a surrogate for compensation of a gaze-holding deficit in MG.

Accuracy of clinical versus oculographic detection of pathological saccadic slowing

Saccadic slowing as a component of supranuclear saccadic gaze palsy is an important diagnostic sign in multiple neurologic conditions, including degenerative, inflammatory, genetic, or ischemic lesions affecting brainstem structures responsible for saccadic generation. Little attention has been given to the accuracy with which clinicians correctly identify saccadic slowing. We compared clinician (n = 19) judgements of horizontal and vertical saccade speed on video recordings of saccades (from 9 patients with slow saccades, 3 healthy controls) to objective saccade peak velocity measurements from infrared oculographic recordings. Clinician groups included neurology residents, general neurologists, and fellowship-trained neuro-ophthalmologists. Saccades with normal peak velocities on infrared recordings were correctly identified as normal in 57% (91/171; 171 = 9 videos × 19 clinicians) of clinician decisions; saccades determined to be slow on infrared recordings were correctly identified as slow in 84% (224/266; 266 = 14 videos × 19 clinicians) of clinician decisions. Vertical saccades were correctly identified as slow more often than horizontal saccades (94% versus 74% of decisions). No significant differences were identified between clinician training levels. Reliable differentiation between normal and slow saccades is clinically challenging; clinical performance is most accurate for detection of vertical saccade slowing. Quantitative analysis of saccade peak velocities enhances accurate detection and is likely to be especially useful for detection of mild saccadic slowing.