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Spiegel, Rainer. "Downbeat nystagmus." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-140001.
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Swart, Wayne. "Nystagmus and eye reflex sensor." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18019.
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Thesis (MScEng)--Stellenbosch University, 2011.ENGLISH ABSTRACT: Nystagmus is an eye movement pattern that consists of a drifting gaze component, known as the slow phase, followed by a corrective quick phase component. The presence of nystagmus or the lack thereof under certain conditions can be used for various diagnostic purposes including the diagnosis of physiological, pathological and neurological conditions. The angular velocity of the quick phase can make the detection of nystagmus a challenging task for the untrained eye, since the quick phases are usually comparable with saccadic eye motions. The goal is thus to develop a fully automated diagnostic tool that can identify the presents of nystagmus in a patient’s eye motions. In this thesis, an appropriate eye tracking method was selected from a number of eye tracking methods that are commonly implemented in the literature. A video-oculography goggle concept was chosen based on criteria such as invasiveness, sampling rate, accuracy and telemedicine capability, amongst other nystagmus related necessities. A binocular video-oculography concept was chosen that satisfied the technical requirements and provided a cost-effective design. An automated analysis algorithm was developed for automatic nystagmus identification from eye motion data. The algorithm was validated by testing the performance of the algorithm on an optokinetic nystagmus signal. It proved to provide a reliable automatic identification of nystagmus beats, even in signals that contained nystagmus as well as random motion components. A statistical analysis showed that the algorithm provided a sensitivity of 91.8% and a specificity of 96.5% for pure nystagmus signals, and a sensitivity and specificity of 87.8% and 91.1% respectively for mixed signals.
AFRIKAANSE OPSOMMING: Nystagmus is ’n oogbewegingspatroon wat bestaan uit ’n dwalende tuurkomponent, wat die stadige fase genoem word, gevolg deur ’n vinnige korrigereringsbeweging wat bekend staan as die vinnige fase. Die teenwoordigheid van nystagmus, of afwesigheid daarvan in sekere gevalle, kan gebruik word in ’n verskeidenheid diagnostiese toepassings, onder andere die diagnose van fisiologiese-, patalogiese- en neurologiese kwale. Die hoeksnelheid van die vinnige fase lei daartoe dat nystagmus dikwels moeilik is om te bespeur vir ongeöefende oë, aangesien dit vergelykbaar is met saccade bewegings. Die doel van hierdie navorsing is dus die ontwikkeling van ’n stelsel wat ’n volledige automatiese identifisering van nystagmus kan behartig. ’n Gepaste oogvolgtegniek was gekies vanuit ’n aantal verskillende oogvolgmetodes wat dikwels in die praktyk gebruik word. Die finale keuse was ’n skermbril, video-oogvolgmetode wat gekies was op grond van kriteria soos onder andere, invallendheid, meetfrekwensie, akkuraatheid en geskiktheid vir telemedisyne toepassings. Die ontwikkelde brilkonsep bied ’n koste-effektiewe oplossing, met die moontlikheid om albei oë te volg en bevredig al die bogenoemde tegniese spesifikasies. ’n Geoutomatiseerde nystagmus identifiseringsalgoritme is ontwikkel. Die algoritme se effektiwiteit is getoets op optokinetiese nystagmusseine. Betroubare resultate is vekry vanaf die algoritme, selfs in die geval van gemengde seine wat bestaan uit arbritrêre- en nystagmus komponente. Statistiese analiese het gewys dat die algoritme ’n sensitiwiteit van 91.8% en ’n spesifisiteit van 96.5% kon behaal vir seine met slegs nystagmus inhoud. Vir gemengde inhoud seine het die algoritme ’n sensitiwiteit van 87.8% en spesifisiteit van 91.1% behaal.
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Harrison, James J. "Volition and automaticity in the interactions of optokinetic nystagmus, infantile nystagmus, saccades and smooth pursuit." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/59168/.
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Volitional target-selecting eye movements, such as saccades or smooth pursuit, are frequently considered distinct and separate from automatic gaze-stabilising eye movements like optokinetic nystagmus or the vestibulo-ocular reflex. This difference is regularly mapped onto brain anatomy, with distinctions made between subcortical, automatic processes; and cortical, volitional ones. However gaze-stabilising and target-selecting eye movements must work together when a moving observer views natural scenes. Yet such co-ordination would not be possible if automatic and volitional actions are sharply divided. This thesis focuses upon interactions between gaze-stabilising and target-selecting eye movements, and how these interactions can aid our understanding of the relationship between automatic and volitional processes. For a saccade executed during optokinetic nystagmus to accurately land on target, it must compensate for the ongoing optokinetic movement. It was found that targeting saccades can partially compensate for concomitant optokinetic nystagmus. The degree of compensation during optokinetic nystagmus was indistinguishable from compensation due to voluntary smooth pursuit displacements. A subsequent experiment found that locations are similarly misperceived during optokinetic nystagmus and smooth pursuit. Furthermore, saccade end-points are subject to the same perceptual mislocalisations. The next experiment established that fast-phases of optokinetic nystagmus can act like competitive saccades and cause curvature in targeting saccades. Moreover, optokinetic nystagmus fast-phases are delayed by irrelevant visual distractors in the same way as saccades (the saccadic inhibition effect). Lastly, it was established that the fast-phases of Infantile Nystagmus Syndrome also show the saccadic inhibition effect. In conclusion, target-selecting and gaze-stabilising eye movements show substantial co-ordination. Furthermore these results demonstrate considerable commonalties between ‘automatic’ and ‘volitional’ eye movements. Such commonalities provide further evidence there is no sharp distinction between automatic and volitional processes. Instead it is likely there are substantial interconnections between automatic and volitional mechanisms, and volition has a graded influence upon behaviour.
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Robert, Matthieu. "Étiopathogénie des nystagmus verticaux du nourrisson." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCB008/document.
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L’étude des nystagmus du nourrisson est difficile pour des raisons méthodologiques. La plupart des études sont donc réalisées chez des adultes et a posteriori. Ces études chez l’adulte ont permis la révision des classifications des nystagmus infantiles, avec la consolidation des concepts de syndrome du nystagmus précoce et de nystagmus de type latent. La séméiologie et l’étiopathogénie des nystagmus du nourrisson – notamment des formes comportant un élément vertical et des formes transitoires – reste donc à étudier. Dans ce but : 1. Nous avons développé de nouvelles techniques d’enregistrement des mouvements oculaires chez les nourrissons, utilisables dans le cadre d’une consultation. Elles incluent de nouveaux stimuli, un appareil d’enregistrement des mouvements oculaires spécialement conçu pour le nourrisson et de nouvelles méthodes d’analyse statistique du signal. Nous avons vérifié la faisabilité de ces enregistrements chez 28 nourrissons atteints de nystagmus. 2. Nous avons étudié systématiquement 32 cas de nystagmus de type spasmus nutans, classiquement considéré comme une entité bénigne idiopathique, avec un examen clinique complet, une imagerie cérébrale, une électrophysiologie visuelle et des enregistrements oculo-moteurs. Dans 53,1% des cas, le spasmus nutans était le symptôme d’une autre maladie : neurologique (34,3%), notamment des gliomes du chiasma (21,9%), ou rétinienne (12,5%). Une atteinte des voies visuelles antérieures est probablement en cause dans la physiopathologie des spasmus nutans. 3. Huit cas de nystagmus ayant conduit au diagnostic de gliome des voies optiques (GVO) ont été également enregistrés et étudiés. L’âge d’apparition du nystagmus allait de 2,5 à 10 mois. Le GVO était toujours chiasmatique et constituait une sous-population spécifique. Le nystagmus était toujours de type spasmus nutans. Les enregistrements oculo-moteurs montraient : une fréquence entre 2,7 et 5 Hz, une morphologie sinusoïdale du nystagmus, une dissociation et une dysconjugaison particulière, avec une opposition de phase (180°) entre les oscillations des deux yeux dans le plan horizontal mais une correspondance de phase dans le plan vertical, à l’origine d’un mouvement semblable à un mouvement de convection. Rarement et brièvement, le rapport de phase changeait. Ces caractéristiques orientent vers des oscillations dans le système des vergences, possiblement la conséquence d’une atteinte des afférences sensorielles des centres du contrôle vergentiel dans le tronc cérébral, secondaire au GVO et survenant pendant la période sensible du développement visuel. 4. Cinq cas de nystagmus upbeat chez des nourrissons avec des rétines et une imagerie cérébrale normale ont été étudiés. Le nystagmus était observé en décubitus et électivement déclenché par des rotations de la tête en position allongée. Dans tous les cas, une résolution spontanée était observée après quelques mois d’évolution. Les caractéristiques de ce type de nystagmus suggèrent une participation du système otolithique, suivie d’une recalibration secondaire des circuits vestibulo-oculaires. En conclusion, le développement de techniques d’enregistrement des mouvements oculaires adaptées aux nourrissons aide à la compréhension de l’étiopathogénie de variétés mal décrites de nystagmus, notamment dans les cas comportant un élément vertical et dans les cas transitoires. Les processus de maturation des voies visuelles antérieures et des centres de contrôle de l’oculomotricité semblent jouer un rôle central dans les mécanismes de ces nystagmusStudying infantile nystagmus during infancy is difficult for methodological reasons. Most such studies have been performed in adults and a posteriori. These studies in adults allowed for an improvement in the existing classifications, with now robust knowledge about the two most frequent varieties of infantile nystagmus: infantile nystagmus syndrome and fusion maldevelopment nystagmus syndrome. The characteristics and pathophysiology of nystagmus in infants–notably varieties of nystagmus with a vertical component and transitory nystagmus– need further study. For this reason: 1. We developed new techniques for the recording of eye movements in infants in the setting of a clinic. They include new stimuli, the use of specially-designed infrared photo-oculography eyetrackers and new statistical analysis paradigms. We assessed these techniques in a population of 28 infants with a nystagmus. 2. We systematically studied 32 cases of spasmus nutans, classically considered an idiopathic entity, with comprehensive clinical examination, brain imaging, electrophysiology, nystagmus recording. In 53.1% of cases, it led to the diagnosis of another condition: a neurological disease (34.3%), including cases of chiasmal gliomas (21.9%), or a retinal dysfunction (12.5%). Anterior visual pathway dysfunction is likely involved in the pathophysiology of spasmus nutans. 3. Eight cases of nystagmus having led to a diagnosis of optic pathway glioma (OPG) were also recorded and studied. Age at nystagmus onset was 2.5-10 months. The associated OPG always involved the chiasm, and represent a specific subpopulation of OPG. Clinically, the nystagmus was always classified as spasmus nutans type. Oculographic recordings showed frequencies of 2.7-5 Hz, sinusoidal waveforms, dissociation and a special type of disconjugacy, with a 180° horizontal phase shift and no vertical phase shift, exhibiting a “convection-like” movement pattern. Rarely and for short periods of time, the phase shift could change. These characteristics point towards oscillations in the vergence system, which could possibly result from the specific disruption of the vergence centres afferences in the brainstem, induced by the OPG during the sensitive period of visual development. 4. Five cases of upbeat nystagmus in infants with normal retinas and normal brain imaging were studied. The nystagmus mostly occurred in supine position and could be triggered by head rotations in the supine position. All resolved spontaneously. The characteristics of this nystagmus suggest an involvement of the otolithic system, with a secondary recalibration of the vestibulo-ocular pathways. In conclusion, the development of infant-friendly devices for eye-movements recording helps providing new insights on the pathophysiology of poorly described varieties of nystagmus, including nystagmus with a vertical component and transitory nystagmus. The maturation process of both the anterior visual pathways and the oculomotor pathways appears to be central in the mechanisms of these nystagmus
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Gadaud, Antoine Élie. "Étude sur le nystagmus thèse pour le doctorat en médecine présentée et soutenue le 29 avril 1869 /." Paris : BIUM, 2003. http://www.bium.univ-paris5.fr/histmed/medica/cote?TPAR1869x097.
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Radinsky, Iliya. "Improved algorithm for classification of nystagmus." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81561.
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An improved algorithm for classification of nystagmus was designed allowing the sorting of response segments even in severely non-linear patients and subjects with abnormally large phase shifts. The algorithm employs a model-based approach that was developed by Rey and Galiana (1991). The improved classification algorithm consists of two essential stages. In the first stage the eye velocity response is classified to obtain best possible estimates of the slow phase eye velocity intervals. In the second stage, the slow phase estimates are used to identify a response phase shift and non-linearity, and compensate for their effects. Multiple tests on simulated data and experimental data obtained from clinical subjects are presented. The results of the tests demonstrate that the algorithm is able to analyze the patient data with a high accuracy even in the presence of noise, eye-blinks and other artifacts.
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Waddington, Jonathan. "Human optokinetic nystagmus : a stochastic analysis." Thesis, University of Plymouth, 2012. http://hdl.handle.net/10026.1/1040.
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Optokinetic nystagmus (OKN) is a fundamental gaze-stabilising response in which eye movements attempt to compensate for the retinal slip caused by self-motion. The OKN response consists of a slow following movement made in the direction of stimulus motion interrupted by fast eye movements that are primarily made in the opposite direction. The timing and amplitude of these slow phases and quick phases are notably variable, but this variability is poorly understood. In this study I performed principal component analysis on OKN parameters in order to investigate how the eigenvectors and eigenvalues of the underlying components contribute to the correlation between OKN parameters over time. I found three categories of principal components that could explain the variance within each cycle of OKN, and only parameters from within a single cycle contributed highly to any given component. Differences found in the correlation matrices of OKN parameters appear to reflect changes in the eigenvalues of components, while eigenvectors remain predominantly similar across participants, and trials. I have developed a linear and stochastic model of OKN based on these results and demonstrated that OKN can be described as a 1st order Markov process, with three sources of noise affecting SP velocity, QP triggering, and QP amplitude. I have used this model to make some important predictions about the optokinetic reflex: the transient response of SP velocity, the existence of signal dependent noise in the system, the target position of QPs, and the threshold at which QPs are generated. Finally, I investigate whether the significant variability within OKN may represent adaptive control of explicit and implicit parameters. iii
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Sarvananthan, Nagini. "Epidemiology and clinical study of nystagmus." Thesis, University of Leicester, 2012. http://hdl.handle.net/2381/10383.
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Nystagmus is a repetitive to and fro movement of the eyes and can affect vision and involve individuals of all ages. Previous research into the pathophysiology of this disease has been based on case series or small numbers of patients. Improvements in and standardisation of electrodiagnostics and eye movement recordings have enabled scientists to diagnose and characterise the different nystagmus types more accurately. Purpose The research into nystagmus carried out at the University of Leicester had several aims. The first population-based study on the prevalence of nystagmus was carried out within the county of Leicestershire. The second study was aimed at examining the clinical features of patients with different types of infantile and neurological nystagmus in order to characterise any specific features associated with this groups of patients. The final study was carried out with the aim of investigating the distribution of refractive errors in patients with nystagmus and to determine if the process of emmetropization in ocular development is influenced by the presence of nystagmus. Methods Ethical approval was obtained. Patients were recruited for the epidemiological study from both the community and hospitals within Leicestershire. Patients for the clinical and refractive error studies were additionally recruited from outside the county. A further 602 normal subjects volunteered to participate in the refraction study. Results The epidemiological study estimates the prevalence of nystagmus to be 16.6 per 10 000 (under 18 population) and 26.5 per 10000 (over 18 population). The clinical study showed differences in visual acuity, stereopsis, anomalous head posture and conjugacy of nystagmus amongst different clinical groups. Finally, the refractive errors study suggests that the process of emmetropization is influenced by the presence of nystagmus. Conclusion These studies provide previously unknown data about nystagmus and provide a platform for further research into this condition.
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Worfolk, Ralph. "Ocular-motor control in congenital nystagmus." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310353.
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Wiblishauser, Kathrin. "Untersuchungen zum auslösenden Rezeptor des vibrationsinduzierten Nystagmus." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969343574.
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Thomas, Shery. "Phenotyping and genotyping of idiopathic infantile nystagmus." Thesis, University of Leicester, 2010. http://hdl.handle.net/2381/7973.
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Background: Nystagmus can be a manifestation of ocular or systemic disorders. However, it may represent a separate disease entity by itself as in idiopathic infantile nystagmus (IIN). In 2004, Kerrison et al. localised the gene causing X-linked IIN to Xq26-27 (NYS1); however, the gene/genes causing IIN had not been identified. Aims and Objectives: The aims of this study were threefold. 1. To ascertain families and singletons (sporadic subjects) with IIN. 2. To further refine the locus NYS1 and to identify the gene causing X-linked IIN 3. To describe and compare the phenotype of subjects with IIN Methods: 39 families and 78 singletons with nystagmus were recruited and phenotyped. Genotyping with microsatellite markers were performed in the X-linked families to refine the genetic interval at Xq26-27. Gene sequencing was carried out by our collaborators (not by the author) at the Sanger Institute. The clinical features and eye movement recordings of 90 subjects with mutations in the FRMD7 gene were compared to 48 subjects with IIN not associated with mutations in this gene (non-FRMD7 group). Results: I: 149 familial subjects and 78 sporadic subjects with IIN were phenotyped. 121 subjects from 30 families were diagnosed to have X-linked IIN while 28 subjects from 9 families had other diagnosis such as albinism and aniridia. II: Genetic mapping in 16 families with X-linked IIN, refined the critical interval at Locus NYS1 (Xq26-17) to a 9mB region between markers DXS8072 and DXS8094 which contained about 80 genes. High throughput DNA sequencing was carried out at the Sanger Institute which led to the discovery of FRMD7, mutations in which is associated with X-linked IIN. III: The median visual acuity in subjects with a FRMD7 mutation was log MAR 0.301. The number of subjects with good stereopsis (Lang positive) was higher in the FRMD7 group (93.4%) compared to subjects in the non- FRMD7 group (78.4%). None of the subjects in the FRMD7 group had severe (>15˚) anomalous head posture (AHP) while 27% of subjects in the non-FRMD7 group had AHP more than 15˚. 52.17% of obligate female carriers of a FRMD7 mutation were clinically affected. Discussion: This study identified the first gene causing idiopathic infantile nystagmus. The phenotypic characteristics of these subjects will help in clinically identifying subjects with IIN due to mutations in FRMD7. In addition it has generated a stage for further research into the mechanisms behind ocular motor control.
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Self, Jay. "A molecular-genetic study of Congenital Nystagmus." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/67625/.
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Nystagmus is a disorder of eye movement characterised by irregular, uncontrolled and repetitive eye movements. It can occur in a broad spectrum of clinical situations and diseases or it may occur in isolation and an inherited disorder. Surprisingly little is known about the underlying mechanisms of ocular-motor control. Similarly, the pathophysiological mechanisms underpinning nystagmus is also poorly understood. By studying pedigrees in whom nystagmus seems to be inherited as an isolated trait (Congenital Idiopathic Nystagmus), it may be possible to identify some of the genetic causes of this disorder and subsequently understand the pathophysiology. This thesis describes a molecular genetic study of congenital nystagmus. A clinical phenotyping study is followed by linkage analysis and positional cloning. A novel nystagmus gene is investigated in a large cohort of Congenital Idiopathic Nystagmus (CIN) patients and X-inactivation studies are performed. Subsequently, cell culture and RT-PCR work is performed to study expression of this gene. Additionally a pedigree with an atypical congenital nystagmus disorder is investigated and a new mutation within a known cerebellar disease gene is identified. This work contributed to the identification of the first gene for Congenital Idiopathic Nystagmus (CIN). The first detailed temporal expression study of the FRMD7 nystagmus gene was also performed in this study which has directed further studies into the pathogenesis of CIN. Identification of a new mutation in the CACNA1A gene in a pedigree with nystagmus and subtle cerebellar signs has lead to the consideration of this gene in patients who present to hospital with isolated atypical nystagmus.
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Young, Allison Stephanie. "Ictal Nystagmus Characteristics of Acute Recurrent Vertigo." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/24097.
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The aim of this doctoral research project was to capture and characterize nystagmus occurring during episodes of vertigo (ictally) by patient-initiated video oculography (VOG), which could help pinpoint the underlying diagnosis. Viewing a patient’s eyes whilst dizzy is a difficult diagnostic task as vertigo may occur at home, and may be significantly reduced by the time a patient presents to a hospital or clinic. Patients with recurrent vertigo were taught to self-record ictal nystagmus using a small, portable VOG device. All underwent history, neurological examination, audiometry, semicircular canal, and otolith function tests as standard of care. In the first study of 117 patients with episodic vertigo, 100% of patients with Ménière’s Disease (MD) and 65.7% of patients with Vestibular Migraine (VM) demonstrated ictal spontaneous nystagmus; high velocity and horizontal (93.0%) in MD (median slow-phase velocity (SPV) 39.7°/s), and lower-velocity, directionally diverse in VM (median SPV 4.9°/s). An SPV >12.05°/s had a sensitivity and specificity of 95.3% and 82.1% for MD. Nystagmus direction-change in the same attack was highly specific for MD (95.7%), as was vertical nystagmus for VM (93.0%). A composite score >3 in nine audiovestibular metrics correctly differentiated MD from VM with a sensitivity and specificity of 95.7% and 95.0%. In cases of positional vertigo, a time-constant <47.3 s separated Benign Paroxysmal Positional Vertigo (BPPV) from MD and VM with a sensitivity of 100% and specificity of 77.8%. Among 102 healthy controls, 30.4% showed very low velocity spontaneous nystagmus and 70.6% had positional nystagmus. The ictal nystagmus characteristics of uncommon presentations of vertigo are also presented. This thesis provides a framework showing that event-monitoring has the potential to assist in early separation of VM and MD in cases of episodic spontaneous vertigo, and BPPV from other causes of positional vertigo. The findings of our studies may hasten diagnosis, improve its accuracy, and guide targeted treatment resulting in better patient outcomes.
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Dunn, Matthew. "Quantifying perception and oculomotor instability in infantile nystagmus." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/59972/.
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The purpose of the studies described herein was to better understand the impact of involuntary eye movements on oculomotor control and perception in infantile nystagmus. Therapeutic interventions that result in slowed nystagmus oscillations often fail to elicit significant quantifiable improvements in visual function, despite patients reporting subjective benefits. It is difficult to justify surgical or pharmacological intervention when the only outcome measures are subjective. Objective quantification of nystagmus eye movements per se usually involves time-consuming manual marking of recordings to both calibrate and analyse data. As a result, analyses are rarely (if ever) performed in the clinical setting. Software was therefore developed to automate calibration and assessment. Psychophysical experiments were undertaken to quantify the spatiotemporal constraints of vision in infantile nystagmus. Visual acuity was measured in the absence of retinal image motion to reveal the maximum improvement to spatial vision that might be expected if nystagmus were halted altogether. The results indicate that poor spatial vision underlies infantile nystagmus, even in cases without comorbid pathology. Gaze acquisition time was compared to stimulus recognition time. The results indicate that infantile nystagmus does not increase visual processing time; rather, redeploying gaze takes longer. An incidental finding revealed a temporal relationship between voluntary saccades and involuntary nystagmus quick phases. Both typically occur together, presumably to maximise efficiency and minimise saccadic suppression. Clinical tests of gaze acquisition time must now be developed, to be used in conjunction with the software developed here, as objective outcome measures of therapeutic interventions.
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Tu, Zhanhan. "Visual abnormalities and sensory integration in infantile nystagmus." Thesis, University of Leicester, 2016. http://hdl.handle.net/2381/37704.
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Introduction: Individuals with albinism and IIN demonstrate retinal structural abnormalities. However, there are no consistent functional retinal differences apparent using full-field flash electroretinography (ffERG). This thesis aims to investigate abnormalities in albinism and IIN at: (i) early stages of visual processing (i.e. retinal deficits) using ffERG; (ii) late stages of visual processing, where the brain integrates visual inputs with other sensory to control posture, using Computerized Dynamic Posturography (CDP). Methods: ffERG and OCT were used to measure functional and structural retinal deficits, respectively. Binocular pupil tracker was used to characterise nystagmus to investigate its effect on ffERG responses. CDP was used to evaluate sensory organization during postural control. Results: Patients with IIN had significant smaller a- and b-wave amplitudes under photopic condition compared to healthy controls. However, individuals with albinism were relatively normal. Test-retest showed that ffERG testing is mostly reliability despite nystagmus being present. Photopic a-wave amplitudes were correlated with combined photoreceptor layer thickness and scotopic S.F. b-wave amplitudes were correlated with the inner nuclear layer thickness. Patients with albinism and IIN have relative good overall postural control. However, both groups present lower visual score and higher somatosensory score than controls. The albinism group also had a higher vestibular sensory score. Conclusion: Reductions of photopic a- and b-wave amplitudes in IIN indicate a subclinical retinal deficit, which has not been previously detected. Interestingly, participants with albinism did not show abnormalities probably due to hypopigmentation shifting the baseline of ERG responses into normal ranges. Correlations between ffERGs and OCT measurements suggest ffERG may contain useful information in albinism and open up an interesting field for future study. Brain plasticity can rearrange the weighting of sensory inputs in both patient groups with the albinism group attaching a stronger weighting to vestibular cues than the other two groups.
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Cyr, D'Arcy D. "The relationship between optokinetic nystagmus and caloric weakness." Scholar Commons, 2003. https://scholarcommons.usf.edu/etd/1004.
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Traditionally, results from caloric testing and optokinetic nystagmus (OKN) testing are analyzed separately because caloric testing is a measure of peripheral function and OKN testing is considered to be a measure of central function. However, there is a connection between the visual system and the vestibular system in the vestibular nucleus of the brainstem. The purpose of this paper was to determine whether a relationship exists between optokinetic nystagmus results and unilateral caloric weakness results. This was determined by conducting a retrospective study of forty patients who exhibited a unilateral caloric weakness greater than or equal to twenty percent and symptoms consistent with an uncompensated vestibulopathy. Patients were later divided into two groups based on involved side. A control group consisting of ten subjects with no reported hearing or vestibular problems was also recruited. When the data of all subjects with a unilateral caloric weakness was considered together, no correlation was found between caloric response (right and left ear) and optokinetic results (gain and slow phase velocity). However, a potential trend emerged at the slow stimulus velocity (15 degrees) when comparing the patients with a right caloric weakness to those with a left caloric weakness. Subjects with a right caloric weakness showed decreased OKN gain for the right eye with a right-moving stimulus compared to the subjects with a left caloric weakness. Alternatively, subjects with a left caloric weakness showed decreased OKN gain for the left eye with a left-moving stimulus compared to the subjects with a right caloric weakness. We conclude that interpretation of OKN along with caloric results may offer potential for identification and tracking of compensation after a unilateral loss of vestibular function, but further research is needed.
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MALAUZAT, OLIVIER. "Les tropies nystagmiques : formes cliniques et pronostic." Nantes, 1990. http://www.theses.fr/1990NANT099M.
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MEILLAT, OLIVIER. "Troubles de la poursuite et de la reponse opto-cinetique dans les strabismes avec nystagmus latent." Lyon 1, 1989. http://www.theses.fr/1989LYO1M393.
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Drumare-Bouvet, Isabelle. "Les nystagmus congenitaux : contribution au diagnostic etiologique, a propos de 88 cas." Lille 2, 1990. http://www.theses.fr/1990LIL2M143.
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Jones, Philip Hugh. "The impact of stress on visual function in nystagmus." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/15155/.
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Infantile Nystagmus Syndrome (INS) is defined as a constant involuntary movement of the eyes, affecting 0.12% of the population. Previous research shows that eye movements in patients with nystagmus increase in stressful conditions, and they report that their vision gets worse. However, there have been no definitive conclusions as to the effect of stress on visual acuity (VA). The aim of the studies described here was to assess visual function, including VA, during periods of stress. The results showed that there was no difference in VA measured with horizontally and vertically oriented Landolt C’s, but, in agreement with published research, VA was found to be poorer when using vertically oriented gratings as compared to horizontal gratings. Using a Trans-Cutaneous Electrical Nerve Stimulation (TENS) machine, an effective clinical stressor, we confirmed that the intensity of nystagmus increased when under stress; however VA, as measured using Landolt Cs, was not affected. Patient response time also increased during stressful periods and was significantly longer in INS than in control subjects. Using a questionnaire, we identified the most stressful situations for patients with nystagmus as being: “finding a person in a crowd” and “crossing a road in heavy traffic”. Under stress, rather than vision becoming blurred, patients with nystagmus reported that they “take longer to see things” and “have difficulty with seeing facial features and small detail”. The results reported here have important implications for patients with nystagmus in the real world, strongly suggesting that, although maximum acuity is unaffected by stress, more time should be allowed for tasks at both work and school. Further research is required to fully understand the changes in other aspects of visual function with stress.
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KIM, MYOUNG SOON. "Etude fonctionnelle et pharmacologique du nystagmus optocinetique du poulet." Université Louis Pasteur (Strasbourg) (1971-2008), 1990. http://www.theses.fr/1990STR13016.
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Grace a l'utilisation d'analogues structuraux du glutamate, nous avons montre que chez le poulet comme chez la grenouille, les cellules ganglionnaires de type on sont impliquees dans le determinisme de la phase lente du noc, mais, contrairement a ce qui est observe chez les batraciens, le canal off ne semble jouer aucun role dans la genese de la phase rapide du reflexe. L'injection intravitreenne d'antagonistes du gaba dans l'il ouvert provoque l'apparition d'un nystagmus spontane qui est independant de la stimulation. Injectees dans l'il ferme, ces substances induisent l'accroisseent du noc monoculaire commande par l'il contralateral, et la disparition de l'asymetrie directionnelle du reflexe. L'administration intracerebrale d'un antagoniste du gaba dans les structures mesencephaliques responsables du noc a permis de confirmer le role specifique de chacun de ces centeres sous-corticaux et de definir l'actin du gaba au niveau de chacune de ces structures. Des phenomnes de compensation dans l'asymetrie directionnelle du noc monoculaire ont ete mis en evidence apres privation visuelle monoculaire prolongee, a la sute d'une paralysie monoculaire. On a demontre l'implication du gaba dans ces phenomenes de plasticite observes chez l'animal adulte
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Schneider, Terri L. "The Incidence of Positional Nystagmus in Healthy Participants Revisited." Scholar Commons, 2002. https://scholarcommons.usf.edu/etd/1528.
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The purpose of this study was to examine the prevalence of nystagmus found in healthy individuals during the positional testing subtest of the standard vestibular test battery. Positional testing involves moving the patient's head, and sometimes the entire body, into a variety of positions while observing eye movement. The hypothesis of the current study was that a relatively low percentage of participants would display nystagmus during positional testing used routinely in clinical diagnostic procedures. The findings were then compared to those of an earlier study in which 82% of normal, healthy individuals were reported to exhibit nystagmus during this testing.
Twenty-five participants were selected that had no known otologic disease and who reported normal hearing sensitivity. In addition, the participants affirmed they had not consumed any alcohol or taken any medications that are known to affect nystagmus. They were then observed in nine different positions. Forty-eight percent of the participants experienced nystagmus in at least one position. Although this percentage was considerably lower than that reported in the earlier study, methodological differences appear to account for the discrepancy. Specifically, the criterion for determining the presence/absence of nystagmus potentially explains the difference in full.
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Yücel, Yeni Hasan. "Le nystagmus optocinetique de la grenouille : approches fonctionnelle pharmacologique et immunocytochimique." Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13168.
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Webb, Nicholas Andrew. "Visual acuity, eye movements, motion sickness and the illusion of motion, with optokinetic stimuli." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340326.
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Drolet, Pierre. "Détection automatique du nystagmus chez un individu sous influence d'alcool /." Trois-Rivières : Université du Québec à Trois-Rivières, 2004. http://www.uqtr.ca/biblio/notice/resume/24025710R.pdf.
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Knapp, Christopher Michael. "Vertical optokinetic nystagmus in adults with or without Parkinson's Disease." Thesis, University of Leicester, 2009. http://hdl.handle.net/2381/8267.
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Background: Horizontal OKN is widely investigated and it is accepted that there is no horizontal OKN asymmetry in healthy adults. Vertical OKN is less well investigated and the direction of vertical OKN asymmetry is unclear. Aims: To investigate vertical OKN asymmetry in healthy individuals under of variety of different experimental conditions comparing: (i) the performance of look versus stare OKN, the effects of (ii) stimulus velocity, (iii) luminance profile, (iv) stimulus size and shape, and (v) distance on vertical OKN responses. The effect of neurological disease on OKN asymmetry in the form of Parkinson's disease was also investigated. Methods: OKN responses were recorded in healthy adult volunteers under a variety of experimental conditions including: (i) working distances of 33cm, lm, 1.2m and 2.5m (ii) sinusoidal and square wave OKN targets (iii) different target sizes ranging in size from 22.4°x28.9° to 65°x 55° (iv) contrasts of 50% to 100% and (v) target velocities of 20°/s and 40°/s investigating 'look and 'stare' OKN response. Stare OKN responses were also compared in subjects with Parkinson's disease and age-matched controls. All data was recorded using an infrared video pupil tracker. Result: No clear vertical OKN asymmetry was seen in normal adult subjects although the degree and direction of vertical OKN asymmetry remained relatively consistent for an individual under different stimulus conditions. Of all stimulus parameters target size had the greatest effect on vertical OKN asymmetry. Stare OKN was sensitive to distance for stimuli moving in the downwards direction. Parkinson's disease patients also had greatly reduced OKN responses for stimuli moving in the downward direction. Discussion: We found sensitivity of 'stare' OKN responses during downward stimulation to both target distance and the effects of Parkinson's disease. It is possible that this is related to the function of OKN during navigation, which is under cerebellar control.
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Mendoza, Juan Carlos. "Investigation of optokinetic nystagmus and the linear vestibular-ocular reflex." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/49906.
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Drolet, Pierre. "Détection automatique du nystagmus chez un individu sous influence d'alcool." Thèse, Université du Québec à Trois-Rivières, 2004. http://depot-e.uqtr.ca/1292/1/000121753.pdf.
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Pasquariello, Giulio <1976>. "Congenital Nystagmus eye movements analysis and oculomotor system models evaluation." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3340/3/pasquariello_giulio_tesi.pdf.
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The term Congenital Nystagmus (Early Onset Nystagmus or Infantile Nystagmus Syndrome) refers to a pathology characterised by an involuntary movement of the eyes, which often seriously reduces a subject’s vision. Congenital Nystagmus (CN) is a specific kind of nystagmus within the wider classification of infantile nystagmus, which can be best recognized and classified by means of a combination of clinical investigations and motility analysis; in some cases, eye movement recording and analysis are indispensable for diagnosis.
However, interpretation of eye movement recordings still lacks of complete reliability; hence new analysis techniques and precise identification of concise parameters directly related to visual acuity are necessary to further support physicians’ decisions. To this aim, an index computed from eye movement recordings and related to the visual acuity of a subject is proposed in this thesis. This estimator is based on two parameters: the time spent by a subject effectively viewing a target (foveation time - Tf) and the standard deviation of eye position (SDp). Moreover, since previous studies have shown that visual acuity largely depends on SDp, a data collection pilot study was also conducted with the purpose of specifically identifying eventual slow rhythmic component in the eye position and to characterise in more detail the SDp. The results are presented in this thesis.
In addition, some oculomotor system models are reviewed and a new approach to those models, i.e. the recovery of periodic orbits of the oculomotor system in patients with CN, is tested on real patients data.
In conclusion, the results obtained within this research consent to completely and reliably characterise the slow rhythmic component sometimes present in eye position recordings of CN subjects and to better classify the different kinds of CN waveforms. Those findings can successfully support the clinicians in therapy planning and treatment outcome evaluation.
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Pasquariello, Giulio <1976>. "Congenital Nystagmus eye movements analysis and oculomotor system models evaluation." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3340/.
Full textAbstract:
The term Congenital Nystagmus (Early Onset Nystagmus or Infantile Nystagmus Syndrome) refers to a pathology characterised by an involuntary movement of the eyes, which often seriously reduces a subject’s vision. Congenital Nystagmus (CN) is a specific kind of nystagmus within the wider classification of infantile nystagmus, which can be best recognized and classified by means of a combination of clinical investigations and motility analysis; in some cases, eye movement recording and analysis are indispensable for diagnosis.
However, interpretation of eye movement recordings still lacks of complete reliability; hence new analysis techniques and precise identification of concise parameters directly related to visual acuity are necessary to further support physicians’ decisions. To this aim, an index computed from eye movement recordings and related to the visual acuity of a subject is proposed in this thesis. This estimator is based on two parameters: the time spent by a subject effectively viewing a target (foveation time - Tf) and the standard deviation of eye position (SDp). Moreover, since previous studies have shown that visual acuity largely depends on SDp, a data collection pilot study was also conducted with the purpose of specifically identifying eventual slow rhythmic component in the eye position and to characterise in more detail the SDp. The results are presented in this thesis.
In addition, some oculomotor system models are reviewed and a new approach to those models, i.e. the recovery of periodic orbits of the oculomotor system in patients with CN, is tested on real patients data.
In conclusion, the results obtained within this research consent to completely and reliably characterise the slow rhythmic component sometimes present in eye position recordings of CN subjects and to better classify the different kinds of CN waveforms. Those findings can successfully support the clinicians in therapy planning and treatment outcome evaluation.
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McIlreavy, Lee. "Fixational and pursuit eye movements in infantile nystagmus : oculomotor control and perception." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/93666/.
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: Infantile nystagmus (IN) is a pathological condition of continuous, horizontal eye oscillations. Despite ongoing eye movements, those with IN do not experience oscillopsia, i.e. the illusory perception that the environment is moving to-and fro. The correct use of neural compensation for their eye movements, just as in typical individuals, is hypothesised to account for this lack of oscillopsia. This neural mechanism requires that an estimate of eye velocity (‘extra-retinal signal’) be compared to an estimate of the motion of the retinal image (‘retinal signal’), and any difference due to object motion. Despite this hypothesis, there have been no previous investigations on how accurately those with IN can estimate object motion. Even in typical adults, eye movement compensation is not perfect, which underlies a number of pursuit-based illusions. One such illusion, the Filehne illusion can be used to investigate the relative mismatch between the extra-retinal and retinal signals as individuals judge their perception of stationarity while attempting to follow a moving target. This illusion was used to investigate, through comparison with typical individuals, whether those with IN correctly recover object motion. Experiments were conducted to characterise the ability of those with IN to fixate as well as follow targets, using a novel two-dimensional eye movement measure. Under repeated testing, the fixation gaze angle at which the IN oscillation is minimum (a null zone) was not consistent. Moreover, those with IN were unable to accurately or precisely follow targets using their slow phase. Results from a comparison of fixation and pursuit performance in those with IN suggested no difference in either the accuracy or precision. Importantly, the psychophysical judgements of those with IN pursuit eye movements are prone to similar compensation errors as typical controls. However, the mechanisms by which this is achieved will require further exploration.
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Jasse, Laurence. "Troubles visuels chroniques, nystagmus pendulaire et oscillopsie dans la sclérose en plaques." Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00666004.
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Les manifestations neuro-ophtalmologiques, observées dans la sclérose en plaques sont parfaitement déterminées à l'heure actuelle. Cependant, l'aspect chronique des troubles visuels résultants n'est pas toujours précisément évalué, or de telles lacunes sont un frein à leur prise en charge. Dans une première partie, les caractéristiques des troubles visuels chroniques ont été mesurées. Il s'agissait de quantifier le pourcentage de plaintes visuelles chroniques chez des patients atteints de sclérose en plaques puis de mesurer le degré d'intensité des troubles visuels chroniques, de déterminer leurs origines physiopathologiques et de rendre compte de leur retentissement sur la qualité de vie des patients se plaignant de troubles chroniques. Les voies visuelles afférentes étaient altérées dans 68% des cas. Des troubles oculomoteurs étaient fréquemment observés (89%) dont le nystagmus pendulaire (28%), source de gêne visuelle. Dans une seconde partie, nous nous sommes donc intéressés au nystagmus pendulaire et à sa conséquence fonctionnelle, l'oscillopsie, afin de proposer une prise en charge spécifique. Néanmoins, les mécanismes de ce nystagmus ne sont pas encore bien définis. Il était donc important de développer une hypothèse explicative à partir de l'observation de deux cas particuliers de nystagmus monoculaire et de démontrer que le nystagmus pendulaire de la sclérose en plaques est à distinguer du nystagmus pendulaire du tremblement oculopalatin, souvent confondus. Enfin, nous proposons une méthode évaluant la détection du mouvement (par stimuli de contraste asservis au regard) ainsi qu'un protocole de stimulation optocinétique tentant de réduire ce symptôme
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Garbutt, Mary Helen Siobhan. "Horizontal and vertical optokinetic nystagmus in normal and abnormal children and adults." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408733.
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Ji, Ting Ting. "Biologically inspired computational models relating vection, optokinetic nystagmus (OKN) and visually induced motion sickness (VIMS) /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?IELM%202008%20JI.
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Kirchhoff, Jan-Birger [Verfasser]. "Multisensorische Determinanten der Standkontrolle bei cerebellären Ataxien mit Downbeat-Nystagmus / Jan-Birger Kirchhoff." Lübeck : Zentrale Hochschulbibliothek Lübeck, 2019. http://d-nb.info/1176157663/34.
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Thomas, Mervyn George. "Genotype-phenotype studies in infantile nystagmus with emphasis on the novel Frmd7 gene." Thesis, University of Leicester, 2012. http://hdl.handle.net/2381/10852.
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FRMD7 mutations are a major cause of idiopathic infantile nystagmus (IIN). Infantile nystagmus can also be associated with albinism, PAX6 mutations and achromatopsia; these disorders are associated with afferent visual anomalies which pose the question could this be a common aetiological factor for infantile nystagmus. The underlying neuroanatomical defects associated with FRMD7 mutations are yet to be determined. A large scale sequencing project was undertaken to genotypically characterize the causative mutations in IIN. The total number of FRMD7 mutations identified was 37 of which 23 were novel. Penetrance of nystagmus in female carriers is related to mutation location rather than mutation type. The genetic basis of idiopathic infantile periodic alternating nystagmus (II-PAN) was unknown. Sequence analysis in II-PAN patients showed that FRMD7 mutations were causative of this disorder. In-situ hybridization results in human embryonic and foetal tissue suggested that the optokinetic reflex and vestibulo-ocular reflex arcs could be involved in the disease pathogenesis. Detailed spatiotemporal expression profiles in the retina suggested that FRMD7 could have a significant role in retinal development. This formed the basis of performing optical coherence tomography (OCT) studies in patients with FRMD7 mutations. Retinal phenotyping studies in patients with FRMD7 mutations showed foveal hypoplasia and abnormal optic nerve head morphology. These findings were also seen in patients with PAX6 mutations and albinism. However in patients with achromatopsia, progressive retinal changes were observed at the fovea: outer nuclear layer thinning and disruption of the inner-outer segment junctions. Atypical foveal hypoplasia was also observed in patients with achromatopsia. The different retinal phenotypes observed with achromatopsia is linked to cone photoreceptor degeneration. A structural grading system was developed for foveal hypoplasia; this takes into account the stage at which the retinal development was arrested. The grade of foveal hypoplasia was a strong predictor of visual acuity. Therefore this thesis shows for the first time that arrested retinal development could be a common aetiological factor to the development of infantile nystagmus. The stage at which the retinal development was arrested is a strong indicator of visual acuity.
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McLean, Rebecca Jane. "Pharmacological treatment of infantile nystagmus and assessing the impact from the patient's perspective." Thesis, University of Leicester, 2015. http://hdl.handle.net/2381/32446.
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Background : Nystagmus is an involuntary to and fro movement of the eyes that can be infantile or acquired and causes reduced vision. Little literature exists documenting how nystagmus affects quality of life and treatment options are largely empirical with very few randomised controlled trials. Methods : Semi-structured interviews of 21 participants were analysed using a constant comparison approach based upon grounded theory. A randomised, triple masked, controlled trial of gabapentin and memantine was performed on 66 participants with infantile nystagmus. Outcome measures were 25% improvement in visual acuity (primary outcome), 25% improvement in eye movement, absolute change in visual function and eye movement and descriptive analysis of nystagmus waveforms responding to treatment. Results : Analysis of participants’ accounts revealed six domains of living that were adversely affected by nystagmus: visual function, restriction of movement (both physical and social), standing out/not fitting in, feelings about the inner self, negativity with regards to the future and relationships. Cosmetic appearance of nystagmus was, for the first time, described as being problematic and additional to other categories was an overarching and universal distress arising from nystagmus affecting every aspect of everyday life. Gabapentin and memantine did not improve visual function as a 25% improvement or when assessing the absolute differences. In contrast null region nystagmus intensity and NAFX were significantly different for treatment as gabapentin reduced intensity and improved NAFX by 25%. For absolute differences in null region nystagmus intensity gabapentin was also significant. Pendular waveforms prevalently appeared in those participants responding to gabapentin. Baseline measurements were often a predictor for success of treatment. Both gabapentin and memantine were both reasonably well tolerated. Conclusion : Interviews revealed universally negative experiences of living with nystagmus that are previously unreported. Gabapentin, and not memantine, significantly reduces eye movement in infantile nystagmus but does not improve visual function.
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Avramidis, Eleftherios. "Optimisation and computational methods to model the oculomotor system with focus on nystagmus." Thesis, University of Exeter, 2015. http://hdl.handle.net/10871/18291.
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Infantile nystagmus is a condition that causes involuntary, bilateral and conjugate oscillations of the eyes, which are predominately restricted to the horizontal plane. In order to investigate the cause of nystagmus, computational models and nonlinear dynamics techniques have been used to model and analyse the oculomotor system. Computational models are important in making predictions and creating a quantitative framework for the analysis of the oculomotor system. Parameter estimation is a critical step in the construction and analysis of these models. A preliminary parameter estimation of a nonlinear dynamics model proposed by Broomhead et al. [1] has been shown to be able to simulate both normal rapid eye movements (i.e. saccades) and nystagmus oscillations. The application of nonlinear analysis to experimental jerk nystagmus recordings, has shown that the local dimensions number of the oscillation varies across the phase angle of the nystagmus cycle. It has been hypothesised that this is due to the impact of signal dependent noise (SDN) on the neural commands in the oculomotor system. The main aims of this study were: (i) to develop parameter estimation methods for the Broomhead et al. [1] model in order to explore its predictive capacity by fitting it to experimental recordings of nystagmus waveforms and saccades; (ii) to develop a stochastic oculomotor model and examine the hypothesis that noise on the neural commands could be the cause of the behavioural characteristics measured from experimental nystagmus time series using nonlinear analysis techniques. In this work, two parameter estimation methods were developed, one for fitting the model to the experimental nystagmus waveforms and one to saccades. By using the former method, we successfully fitted the model to experimental nystagmus waveforms. This fit allowed to find the specific parameter values that set the model to generate these waveforms. The types of the waveforms that we successfully fitted were asymmetric pseudo-cycloid, jerk and jerk with extended foveation. The fit of other types of nystagmus waveforms were not examined in this work. Moreover, the results showed which waveforms the model can generate almost perfectly and the waveform characteristics of a number of jerk waveforms which it cannot exactly generate. These characteristics were on a specific type of jerk nystagmus waveforms with a very extreme fast phase. The latter parameter estimation method allowed us to explore whether the model can generate horizontal saccades of different amplitudes with the same behaviour as observed experimentally. The results suggest that the model can generate the experimental saccadic velocity profiles of different saccadic amplitudes. However, the results show that best fittings of the model to the experimental data are when different model parameter values were used for different saccadic amplitude. Our parameter estimation methods are based on multi-objective genetic algorithms (MOGA), which have the advantage of optimising biological models with a multi-objective, high-dimensional and complex search space. However, the integration of these models, for a wide range of parameter combinations, is very computationally intensive for a single central processing unit (CPU). To overcome this obstacle, we accelerated the parameter estimation method by utilising the parallel capabilities of a graphics processing unit (GPU). Depending of the GPU model, this could provide a speedup of 30 compared to a midrange CPU. The stochastic model that we developed is based on the Broomhead et al. [1] model, with signal dependent noise (SDN) and constant noise (CN) added to the neural commands. We fitted the stochastic model to saccades and jerk nystagmus waveforms. It was found that SDN and CN can cause similar variability to the local dimensions number of the oscillation as found in the experimental jerk nystagmus waveforms and in the case of saccade generation the saccadic variability recorded experimentally. However, there are small differences in the simulated behaviour compared to the nystagmus experimental data. We hypothesise that these could be caused by the inability of the model to simulate exactly key jerk waveform characteristics. Moreover, the differences between the simulations and the experimental nystagmus waveforms indicate that the proposed model requires further expansion, and this could include other oculomotor subsystem(s).
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Spiegel, Rainer Christian [Verfasser], and Michael [Akademischer Betreuer] Strupp. "Downbeat nystagmus : changes during daytime and its treatment / Rainer Spiegel. Betreuer: Michael Strupp." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2011. http://d-nb.info/1020362324/34.
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Munro, N. A. R. "The control of saccadic and smooth pursuit eye movements in patients with lesions of the central nervous system." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319050.
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Christie, Jock Robert Ian. "Modulation of optokinetic nystagmus in humans by linear acceleration, and the effects of spaceflight." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/43248.
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Anil, Kumar Amrutur Saryanarayana. "Clinical and ocular motor characterisation of infantile and acquired nystagmus using eye movement recordings." Thesis, University of Leicester, 2015. http://hdl.handle.net/2381/32220.
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Our aim was to characterise the ocular motor abnormalities in infantile (IN) and acquired nystagmus (AN) using eye movement recordings in order to improve diagnosis and understanding of these diseases. The first aim was to compare a genetically homogenous idiopathic IN group (FRMD7-IN) with albinism associated IN. The second aim was to investigate acquired pendular nystagmus (APN) due to MS along with other ocular motor abnormalities, in relation to disease severity and MS subtype. Eye movements were recorded in all IN and AN participants (n=117). Ocular motor characteristics of the nystagmus were analysed. Other clinical features were compared including strabismus, stereopsis and anomalous head posture (AHP) in IN and the disability score and MS subtype in MS. FRMD7-IN contained higher proportions of pendular waveform compared with albinism. Nystagmus frequency was significantly lower in albinism compared with FRMD7-IN. Strabismus and AHP were more frequent in albinism, and stereopsis was worse compared with FRMD7-IN. In MS APN coexisted with various other ocular motor deficits including gaze-evoked nystagmus, internuclear ophthalmoplegia and square wave jerks although the occurrence of these was not related to MS severity or subtype. The APN was dysconjugate mainly due to a difference in amplitude between the two eyes rather than frequency. There was no clear change in APN parameters with MS severity or subtype. We describe for the first time the differences in nystagmus characteristics associated with albinism and FRMD7- IN which may be useful information in the future elucidation of mechanisms underlying the nystagmus and also in diagnosis. In MS we confirm that APN is mainly dysconjugate due to amplitude and can co-exist with various ocular motor abnormalities. Eye movement recordings can assist in differentiating various ocular motor abnormalities in IN and AN that are difficult to characterise on clinical examination.
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Arzi, Mohammad. "Traitement automatique des signaux vestibulo-oculaires et optocinétiques." Lyon, INSA, 1986. http://www.theses.fr/1986ISAL0025.
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Analyse entièrement automatique et fiable des réflexes vestibulo-oculaire{R. V. 0) et optocinétique (R. O. C. ). Pour cette analyse, un nouvel algorithme a été développe qui effectue une classification des phases lentes et rapides du nystagmus oculaire. La méthode utilisée pour le classement des phases lentes, fait appel à des notions de la théorie des sous ensembles flous. On peut résumer la méthode comme suit : 1)Une classification globale des phases lentes est réalisée. A chaque point du nystagmus une valeur est affectée qui détermine, dans un contexte global du nystagmus, son appartenance aux phases lentes. 2)Se basant sur ce classement, la forme globale de l'évolution des phases lentes est révélée en faisant un ajustement de courbe au sens des moindres carrés pondérés par la fonction d'appartenance obtenue en 1). 3)Le classement des phases lentes est raffiné en se basant sur la forme globale que l'an a obtenue en 2). Cette fois on obtient une classification locale des phases lentes. 4)La "Position Cumulée de la Phase Lente" (P. C. P. L. ) de l’œil est construite en supprimant les phases rapides et en mettant bout à bout les phases lentes et en faisant une interpolation pendant les phases rapides. 5)Un ajustement de courbe sur la P. C. P. L. Est effectué. Cet ajustement se fait au sens des moindres carrés pondérés par la dernière fonction d'appartenance. Les paramètres des R. V. O. Ou R. O. C. Sont calculés en se basant sur cette dernière courbe.
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Gliddon, C. M., and n/a. "An attempt to elucidate the role of GABAA receptors in vestibular compensation." University of Otago. Department of Pharmacology & Toxicology, 2006. http://adt.otago.ac.nz./public/adt-NZDU20070427.150754.
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Loss of sensory input from one vestibular labyrinth by unilateral vestibular deafferentation (UVD) results in a severe ocular motor (i.e., spontaneous nystagmus (SN)) and postural syndrome (i.e., yaw head tilt, (YHT) and roll head tilt (RHT)) which compensates over time in a behavioural recovery process known as vestibular compensation. It is generally accepted that the UVD-induced neuronal imbalance in the resting activity between the two vestibular nuclear complexes (VNCs) generates the ocular motor and postural syndrome and that the restoration of the resting activity in the ipsilateral VNC plays a causal role in the compensation of the static symptoms. γ-Aminobutyric acid (GABA) and the GABAA and GABAB receptors within the VNC are involved in normal vestibulo-ocular and --spinal pathways and it has been suggested that modification of GABAergic inhibition may be a mechanism responsible for the recovery of resting activity in the ipsilateral VNC. Behavioural, western blotting, and immunoassay techniques were used to address the role of the GABAA receptor in the VNC during vestibular compensation.
The first study involved the characterization of SN, YHT, and RHT compensation in guinea pigs that had been anaesthetized with isoflurane during the UVD. These animals compensated rapidly (i.e., 30 hrs) and the time to compensate was independent of the duration of the anaesthesia. Using the 30 hrs time frame, the effects of the chronic infusion of the GABAA receptor agonist (muscimol) / antagonist (gabazine) into either the ipsilateral or the contralateral VNC on the compensation of SN, YHT, and RHT, were determined. Infusion of muscimol (250, 500, and 750 ng) into the contralateral VNC and gabazine (31.25, 62.5 and 125 ng) into the ipsilateral VNC significantly affected YHT and RHT (p < 0.05), but not their rate of compensation (p > 0.05). Interestingly, the effects of muscimol and gabazine on YHT and RHT were consistent throughout the first 30 hrs post-UVD. At 30 hrs post-UVD, the pumps were disconnected. In both experimental groups, the value and direction of the YHT and RHT returned to vehicle levels. Infusion of muscimol (62.5, 125, and 250 ng) into the ipsilateral VNC and gabazine (125, 375, and 750 ng) into the contralateral VNC had little effect on YHT and RHT, or their rate of compensation. At 30 hrs post-UVD, the pumps were disconnected. In both experimental groups, the value and direction of the YHT and RHT returned to vehicle levels. These results suggest that the ipsilateral gabazine and contralateral muscimol infusions were modifying the expression of the symptoms without altering the mechanism of compensation. Furthermore, the mechanism responsible for vestibular compensation can cope with the both the GABAA receptor-mediated and the UVD-induced decrease in resting activity. Results from the western blotting study indicated that compensation of SN, YHT, and RHT is not associated with changes in the protein levels of the GABAA receptor α₁, β₂, or γ₂ subunits. Compensation of SN, YHT, and RHT is associated with an elevation in cortisol salivary levels. Overall, the results suggest that the GABAA receptors are involved in the expression of YHT and RHT, but not in the mechanism that is responsible for their compensation.
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Naumann, Thomas [Verfasser]. "Differentielle Wirkung von 4-Aminopyridin auf die verschiedenen Komponenten des Downbeat-Nystagmus-Syndroms / Thomas Naumann." Lübeck : Zentrale Hochschulbibliothek Lübeck, 2018. http://d-nb.info/1152029797/34.
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Farooq, Shegufta Jabeen. "Torsional optokinetic nystagmus : response characteristics measured in the normal population and patients with ocular motor disorders." Thesis, University of Leicester, 2009. http://hdl.handle.net/2381/7364.
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This thesis presents the first detailed study of the torsional optokinetic nystagmus (tOKN) response in the normal population and in patients with oculomotor disorders. The effects on the tOKN response of: (i) stimulus velocity, (ii) stimulus area, and (iii) aging, were investigated in the normal population. The tOKN response was also evaluated in patients with long standing oculomotor disorders, namely strabismus and infantile nystagmus. Torsional OKN responses were recorded using infrared video-oculography and were elicited with volunteers fixating the centre of a large-field rotating sinusoidal grating pattern. Torsional OKN responses were present in all normal young volunteers (n=20) to stimuli rotated in clockwise and anticlockwise directions, and a linear relationship was observed between log stimulus velocity and tOKN slow phase velocity. Torsional OKN also showed brisk responses to peripheral field stimulation in the same subjects. The first report of a significant increase with age in the proportion of absent tOKN responses is also described in normal subjects aged between 19-72 years (n=30). The tOKN response was investigated for the first time in strabismic patients (n=16), comparing horizontal and vertical OKN responses, and also in patients with infantile nystagmus (n=16). OKN responses from strabismus patients demonstrated consistent asymmetry in horizontal and vertical directions. However, a significantly higher incidence of absent tOKN responses in both intorsion and extorsion directions were observed in comparison to controls. Torsional OKN was present in 3 of 16 patients with infantile nystagmus. Torsional OKN is a well developed reflex in the normal population with the capacity to respond in proportion to stimulus velocity and area of stimulation. However, the tOKN response is dramatically affected by (i) the effects of aging, (ii) by the interruption of binocular visual development in patients with strabismus, and (iii) by the presence of infantile nystagmus.
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BRISKER, THIERRY-PAUL. "L'epreuve calorique dans l'examen vestibulaire : le papillon inverse, essai d'interpretation a la lumiere des experiences faites en impesanteur." Limoges, 1988. http://www.theses.fr/1988LIMO0126.
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Gitchel, George. "Oculomotor Control in Patients with Parkinson's Disease." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/68.
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There have been few studies investigating the eye movement behavior of Parkinson’s disease patients during fixation. This study objectively measured the eye movements of 36 patients with Parkinson’s disease, and 20 age matched controls. Stimuli consisted of ten standardized text passages first organized by Miller and Coleman. In addition, subjects followed a randomly displaced step jump target motion. Pendular nystagmus was found in all Parkinson’s subjects, with an average frequency of 7.44 Hz. Saccadic peak velocity and duration along the main sequence were not statistically different from controls. A slower rate of reading was also noted in the Parkinson’s group in terms of characters per minute, but with no more regressions than normal. Rate of square wave jerks was also found to be normal. This suggests that the hallmark feature of eye movements in Parkinson’s disease is a pendular nystagmus during fixation, and all saccadic activity to be normal.
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Wang, Zhong. "A UNIFYING HYPOTHESIS FOR THE MULTIPLE WAVEFORMS OF INFANTILE NYSTAGMUS AND THEIR IDIOSYNCRATIC VARIATION WITH GAZE ANGLE AND THERAPY." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1210605209.
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Müller-Schunk, Stefanie Elisabeth Ingeborg. "fMRT-Aktivierungen des frontalen und parietalen Augenfeldes sowie MT-V5 während der Durchführung von Sakkaden, smooth pursuit und optokinetischem Nystagmus." [S.l.] : [s.n.], 2004. http://edoc.ub.uni-muenchen.de/archive/00003211/.
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