Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Eye Movement Measurements”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources
PubMed1988

Decreased slow-wave sleep and enlarged lateral ventricles in schizophrenia.

All-night electroencephalogram measures were evaluated against computed tomography scan measures, negative symptoms, and premorbid personality assessment in ten drug-free male schizophrenic patients. Computed tomography scan measures included ventricle brain ratio, cortical atrophy, and width of the third ventricle. Decreased stage-4 sleep was associated with enlarged VBR, poor premorbid functioning, and negative symptoms. Size of the VBR accounted for 58.5% of the variance in stage-4 sleep. Brain atrophy was associated with longer sleep latency but with less arousals once the patients were asleep. Rapid-eye-movement measures did not correlate significantly with any of the variables examined. Our data suggest that decreased slow-wave sleep and ventricle size are associated in schizophrenia.

Adult↗
PubMed2006

The impact of letter detection on eye movement patterns during reading: Reconsidering lexical analysis in connected text as a function of task.

A comparison was made between reading tasks performed with and without the additional requirement of detecting target letters. At issue was whether eye movement measures are affected by the additional requirement of detection. Global comparisons showed robust effects of task type with longer fixations and fewer word skippings when letter detection was required. Detailed analyses of target words, however, further showed that reading with and without letter detection yielded virtually identical effects of word class and text predictability for word-skipping rate and similar effects for different word viewing duration measures. The overall oculomotor pattern suggested that detection does not substantially shift normal reading movements in response to lexical cues and thereby indicated that detection tasks are informative about word and specifically word class processing in normal reading.

Eye Movements↗
PubMed2006

Effect of the background on the disparity-induced ramp vergence response in humans.

PURPOSE: Our purpose was to investigate the changes in the dynamic property of vergence eye movements caused by changes in the co-existing stationary background in the central visual field. METHODS: Disparity-driven target movement was presented virtually by a head-mounted liquid-crystal display. Two targets were used: a bar-shaped target that moved between 2 and 0.5 m along the mid-sagittal line at a speed of 50 cm/s (vergence target) and a background image of a cross-shaped target that stayed at a distance of 2 m (background target). Eight normal subjects participated in the experiments. The subject was asked to follow the vergence target while the configuration of the background target was randomly changed among four conditions in each experiment: the length (experiment 1) or the width (experiment 2) of the horizontal and vertical lines composing the cross of the background target was each randomly changed among four conditions. A limbus tracker was used to measure eye movements. RESULTS: In experiment 1, there was a negative correlation between the amplitude of the vergence eye movements and the lengths of the lines of the cross in each of five subjects (mean r = 0.018, n = 48 in each subject). Similarly, in experiment 2, there was a negative correlation between the amplitude of the vergence eye movements and the width of the lines of the cross in each of 8 subjects (mean r = -0.12, n = 48 in each subject). CONCLUSION: The vergence response to a target object significantly differs depending on the texture of background objects on the visual axis.

Adult↗
PubMed2005

Developmental dyslexia in a regular orthography: a single case study.

This study of an adult case examined in detail with eye movement measures the reading speed problem which is characteristic for developmental dyslexia in regular orthographies. A dramatic length effect was found for low frequency words and for pseudowords, but not for high frequency words. However, even for high frequency words it was found that reading times were substantially prolonged although number of fixations did not differ. A neurocognitive assessment revealed no visual deficits (parallel processing, precedence detection, coherent motion detection) but speed impairments for certain verbal and phonological processes. We propose that the reading difficulties are phonological in nature, but these difficulties become manifest as inefficiency and not as inability.

Adult↗
PubMed1994

Repeated optokinetic stimulation in conditions of active standing facilitates recovery from vestibular deficits.

Successful results obtained by training sessions using optokinetic (OK) stimulations in order to rehabilitate patients with balance disorders motivated this study. The purpose of the study was to measure eye movement parameters and body stabilization during OK stimulation before and after the rehabilitation program. Two populations of patients were studied: bilateral and unilateral labyrinthine-defective patients. Before training, the OK nystagmus (OKN) showed irregularities of the slow-phase velocity (SPV) as well as a reduced number of beats (frequency) when compared with a control group of age-matched healthy volunteers. After training, the SPV became more regular (decrease in SD) and the frequency was similar to the control group's (3 Hz). Body stabilization was measured by dynamic posturography (Equitest) at the beginning and at the end of the training program. At the end of the training program, the patients were asymptomatic and there was a significant correlation between the Equitest results and the modification of the OKN parameters.

Adult↗
PubMed1994

[Recording characteristics of the eye mark recorder in measurements of vertical eye movements].

Electronystagmography (ENG) has been widely used in physiological studies of eye movements. It is generally known that ENG is at a disadvantage in recording the vertical component of eye movements, and thus there has been a great deal of difficulty in physiological studies of vertical eye movements using ENG. The eye mark recorder is an instrument which has already been used in the study of visual point movement in various situations. We tried to apply the eye mark recorder to the recording of eye movements in normal volunteers, and then compared its recording characteristics with those of ENG. When recording vertical eye movements with the eye mark recorder there is little baseline drift and no confusing waves caused by blinking, which is sometimes misinterpreted as nystagmus. The result is easy calibration of the device and more accurate measurement of the slow-phase velocity of nystagmus than ENG. Recording with the eye mark recorder is atraumatic and allows binocular visual stimulation. There are certain other techniques, such as search coil or video oculography, which allow more accurate recording of vertical eye movements than ENG. The search coil techniques, however, requires the attachment of a measuring contact lens during the examination and video oculography is still in development process, so both of them are difficult to use widely. Thus, we found that the eye mark recorder has a great advantage in recording the slow-phase eye velocity of vertical nystagmus and the vertical component of smooth eye movements in humans. We think that eye mark recorder can serve as a powerful new tool to investigate vertical OKN and OKAN.

Adult↗
PubMed1988

Smooth pursuit eye movements in schizophrenics: quantitative measurements with the search-coil technique.

Eye movements of five schizophrenic and five normal subjects were measured with the magnetic-field search-coil technique. Subjects followed targets moving smoothly at various speeds, either unpredictably in a step-ramp fashion or predictably in a triangular wave. The tracking stimulus was either a small dot or a large, richly-textured image that occupied a large portion of the visual field. Tracking by schizophrenics was abnormal; it was punctuated by catch-up saccades that corrected for smooth following movements of inadequate velocity. We did not, however, find saccadic intrusions, such as square wave jerks. Under all tracking conditions steady-state gains (eye velocity/target velocity) and, in the case of step-ramps, average acceleration in the first 120 ms were lower in patients than in normal subjects. The differences were most pronounced for tracking of the small target, moving at the highest speed tested (30 degree/s), in the nonpredictable, step-ramp waveform. With this stimulus mean steady-state gain was 0.36 (SD +/- 0.12) for the schizophrenic patients and 0.73 (SD +/- 0.11) for the normal subjects. When the target was changed to the large-field stimulus or moved in a predictable (triangular-wave) fashion, tracking improved in both patients and normal subjects, and even more so when these features were combined.

Adult↗
PubMed1998

Pendular nystagmus in patients with peroxisomal assembly disorder.

BACKGROUND: Pendular nystagmus commonly occurs in congenital and acquired disorders of myelin. OBJECTIVE: To characterize the nystagmus in 3 siblings with an infantile form of an autosomal recessive peroxisomal assembly disorder causing leukodystrophy. DESIGN: We examined visual function and measured eye movements using infrared oculography. We noted changes in eye speed and frequency before and after the administration of gabapentin to 1 patient. RESULTS: All 3 siblings showed optic atrophy and pendular nystagmus that was predominantly horizontal, at a frequency of 3 to 6 Hz, with phase shifts of 45 degrees to 80 degrees between the oscillations of each eye. Gabapentin administered to 1 child caused a modest improvement of vision and the reduction of the velocity and frequency of oscillations in the eye with worse nystagmus. CONCLUSION: The pendular nystagmus in these patients was due to their leukodystrophy and may have a similar pathogenesis to the oscillations seen in other disorders affecting central myelin.

Adolescent↗
PubMed1998

Oculomotor testing in the differential diagnosis of degenerative ataxic disorders.

BACKGROUND: Oculomotor abnormalities have been reported in patients with degenerative ataxic disorders. OBJECTIVE: To assess the diagnostic sensitivity and specificity of oculomotor deficits in patients with Friedreich ataxia (FA), cerebellar atrophy (CA), and olivopontocerebellar atrophy (OPCA). SETTING: Neurology clinic at a university hospital in Lübeck, Germany. PATIENTS: Seven patients with FA, 9 with CA, and 10 with OPCA were studied. These patients were selected from an ongoing follow-up study. MAIN OUTCOME MEASURES: Eye movements were recorded by electro-oculography; an extensive battery of quantitative tests was used. RESULTS: A proven CAG repeat expansion on chromosome 6 or 14 was significantly associated with reduced saccadic eye velocity and vertical gaze palsy (P<.001, Mann-Whitney U test). All 6 patients with OPCA and slow saccades had an autosomal-dominant inheritance; 4 of them were proved to have spinocerebellar atrophy type 1. In 9 of these patients (4 with FA, 1 with CA, and 4 with OPCA), the genetic defect could not be identified. Saccadic dysmetria, impairment of smooth pursuit and optokinetic nystagmus, deficient suppression of the vestibulo-ocular reflex by either visual or otolith input, and pathological nystagmus were attributed to degenerative lesions in different parts of the cerebellum. However, these symptoms failed to clearly distinguish between the different groups of patients, whereas decreased vestibulo-ocular reflex gain, slow saccades, and vertical gaze palsy pointed to an extracerebellar manifestation of the degenerative disease, occurring only in patients with OPCA and FA. CONCLUSIONS: In this prospective study, oculomotor disturbances were mainly related to cerebellar dysfunction. Only a few of them were caused by extracerebellar manifestations of the disease, such as slowing of saccades, which was characteristic for patients with OPCA of autosomal-dominant inheritance.

Adult↗
PubMed2005

Anti-GAD antibodies and periodic alternating nystagmus.

BACKGROUND: Autoantibodies directed against glutamic acid decarboxylase (GAD-Ab) have recently been described in a few patients with progressive cerebellar ataxia, suggesting an autoimmune physiopathologic mechanism. OBJECTIVE: To determine the exact role of GAD-Ab and gamma-aminobutyric acid (GABA)-ergic neurotransmission in the pathogenesis of cerebellar ataxia. DESIGN: Case report. SETTING: University neurological hospital. PATIENT: We report the case of a patient with subacute cerebellar ataxia associated with GAD-Ab showing periodic alternating nystagmus (PAN). INTERVENTION: Baclofen, a GABAergic medication, was given to the patient. MAIN OUTCOME MEASURES: Eye movement recording of spontaneous nystagmus and postrotatory vestibular responses. RESULTS: Baclofen was effective in suppressing PAN and improving postrotatory vestibular responses but not for improving cerebellar ataxia. CONCLUSION: The presence of PAN and the response to baclofen provide a unique opportunity to suggest a direct role of GAD-Ab in cerebellar dysfunction in this patient.

Aged↗
PubMed1996

Complications of the canalith repositioning procedure.

OBJECTIVE: To describe the conversion of benign paroxysmal positional vertigo involving the posterior canal into benign paroxysmal positional vertigo involving the anterior or horizontal canals after treatment using the canalith repositioning maneuver. DESIGN: Retrospective study of outcome. SETTING: Outpatient clinic. PATIENTS: Consecutive sample of 85 patients diagnosed as having benign paroxysmal positional vertigo affecting the posterior canal. Identification of posterior canal involvement was based on the observation of the direction of the vertical component of nystagmus after the Hallpike-Dix maneuver. INTERVENTION: Canalith repositioning maneuver. MAIN OUTCOME MEASURE: Eye movements were observed about 1 week after the treatment. The direction of nystagmus elicited after movement of the patient into the Hallpike-Dix position indicated which canal was involved in the patients who had not responded to treatment. RESULTS: Of the 85 patients studied who originally had posterior canal benign paroxysmal positional vertigo, five (6%) had anterior canal (n=2) or horizontal canal (n=3) positional vertigo after undergoing this maneuver. CONCLUSION: Careful observation of the direction of the nystagmus is necessary for correct identification of which canal is involved in patients who do not respond to the initial treatment using the canalith repositioning maneuver.

Adult↗
PubMed2003

Effects of ethanol on anti-saccade task performance.

It has been shown that saccade-related neurons in the superior colliculus (SC) display an increased level of prestimulus activity and a higher stimulus-related burst in action potentials preceding direction errors in the anti-saccade task compared with correct anti-saccades. From this, it has been hypothesized that errors occur when the incoming visual signal in the SC passes a threshold and triggers a reflexive saccade. This hypothesis predicts that an attenuated visual signal will reduce the number of direction errors. Since ethanol has been shown to have a suppressive effect on cortical visual event-related potentials (ERPs), the purpose of the present study was to investigate the effects of moderate ethanol consumption on anti-saccade performance. Under both placebo and ethanol conditions, we recorded ERPs and measured eye movements in male subjects during the performance of an anti-saccade task in which the fixation point disappeared 200 ms prior to stimulus presentation. Compared with the placebo condition, we found in the ethanol condition: (1). a decrease in ERP amplitudes during the gap period and after stimulus presentation, (2). an increase in the latencies of anti-saccades, and (3). a decrease in the percentage of direction errors. These data demonstrate the effects of ethanol on anti-saccade task performance and provide further support for the hypothesis that errors in the anti-saccade task are triggered by the incoming visual signal.

Adult↗
PubMed2005

Vestibulo-collic reflex (VCR) in mice.

The vestibulo-collic reflex (VCR) attempts to stabilize head position in space during motion of the body. Similar to the better-studied vestibulo-ocular reflex, the VCR is subserved by relatively direct, as well as indirect pathways linking vestibular nerve activity to cervical motor neurons. We measured the VCR using an electromagnetic technique often employed to measure eye movements; we attached a loop of wire (head coil) to an animal's head using an adhesive; then the animal was gently restrained with its head free to move within an electromagnetic field, and was subjected to sinusoidal (0.5-3 Hz) or abrupt angular acceleration (peak velocity approximately 200 degrees/s). Head rotation opposite in direction to body rotation was assumed to be driven by the VCR. To confirm that the compensatory head movements were in fact vestibular in origin, we plugged the horizontal canal unilaterally and then retested the animals 2, 8 and 15 days after the lesion. Two days after surgery, the putative VCR was almost absent in response to abrupt or sinusoidal rotations. Recovery commenced by day 8 and was nearly complete by day 15. We conclude that the compensatory head movements are vestibular in origin produced by the VCR. Similar to other species, there are robust compensatory mechanisms that restore the VCR following peripheral lesions.

Animals↗
PubMed2005

Sensory input from the moving hand influences saccadic eye movements during reading.

Reading involves saccadic eye movements. Measured reading time and the number of mistakes made while reading reflect the speed and accuracy of the saccades in target localization, if all other factors influencing these parameters are kept constant. The observed phenomenon that reading a book is easier when it is held in an individual's hand than when it is not, especially when movement of the reading text occurs while travelling in a vehicle, raises the question of the role of sensory input from the moving arms in guiding saccades in the direction in which the text is moved. To address this question, 12 healthy subjects (6 males and 6 females), aged 19-21 years took part in this study where reading time and the number of mistakes made while reading a non-moving standardized printed text was noted. Similar printed texts were read by the subjects while mechanically moving them at different fixed speeds in the horizontal plane, with and without the subject's arms moving with the text. At each speed, the reading time recorded when the subject's arms moved with the text was significantly lesser than when they did not (P<0.05). The number of mistakes made were significantly more when not moving the arms than when moving them with the text, at higher speed of text movement (P<0.05). The results indicate that sensory input from the passively moving arms guided saccades in the direction of movement of the text during reading.

Adult↗
PubMed1999

[Microperimetry and reading saccades in retinopathia solaris. Follow-up with the scanning laser ophthalmoscope].

UNLABELLED: Patients with solar retinopathy often complain of minute central scotomas and are handicapped when reading. The purpose of this study was to verify scotomas that are too small to be detected by standard perimeters and to analyze patients' reading patterns. METHODS: Nineteen patients (12 female, 7 male, aged 5-46 years) with acute solar retinopathy after watching a solar eclipse on 12 October 1996 underwent scanning laser ophthalmoscope (SLO) microperimetry within 10 days after exposure using stimulus size Goldmann I (0.11 degree) with the 20 degrees field. Size and depth of scotomas were measured. Eye movements during reading were recorded on videotape. Follow-up was at 1 and 6 months. RESULTS: Thirty-one eyes (7 patients unilateral, 12 bilateral) showed scotomas. Four eyes showed anatomic changes in the retinal pigment epithelium but no functional loss. VA was 0.16 to 0.5 in 5 eyes, 26 had VA of 0.8-1.2. Scotomas could be detected in all eyes with subjective impairment. Scotoma size varied from 0.3 to 1.7 degrees (1 patient 6 degrees). Forty-four percent were deep scotomas (0 dB). All defects improved at 1 and at 6 months; 25% were no longer detectable. Reading speed was reduced in 75% of eyes (42% at 6 months): 200-560 signs/min, median: 510, normal > or = 660 (at 6 months: 350-920 signs/min, median 670). This was especially due to increased number of regressions (in 81% of eyes, 21% at 6 months). The frequency and width of saccades were no different from normal subjects. CONCLUSION: Minute scotomas (diameter = 0.3 degree) can be detected with the SLO. All patients showed objective improvement of their field defect up to 6 months, even when this was not noted by the patient or thought to be due to habituation. Small scotomas can dramatically reduce reading performance.

Adolescent↗
PubMed1992

Visual suppression of torsional vestibular nystagmus in rhesus monkeys.

Juvenile rhesus monkeys, placed on a motorized turntable, were rotated at constant velocity and then decelerated about an Earth-vertical axis. The animals were implanted with dual search coils to measure eye movements in three dimensions. By changing the monkey's body position (upright, ear-down, supine), postrotatory nystagmus was elicited in the horizontal, vertical, or torsional direction. Peak slow phase eye velocity and time constant of velocity decay were compared between decelerations in the dark and in the light. In all nystagmus directions, illumination reduced the time constant (Tc) to values around 5 sec. Peak velocity (Vp) was markedly attenuated in the horizontal and vertical directions (around 50%), but the effect of light on Vp in the torsional direction was small (less than 20%). These findings were independent of the velocity step size. Our hypothesis is that the two dynamic components of optokinetic nystagmus, as they interact with postrotatory nystagmus during visual suppression, differ in their dimensionality: the early component (fast component, direct pathway, pursuit system) is mainly activated in the horizontal and vertical directions, while the late component (slow component, indirect pathway, optokinetic system) effectively operates in all three dimensions.

Animals↗
PubMed2005

General vestibular testing.

A dysfunction of the vestibular system is commonly characterized by a combination of phenomena involving perceptual, ocular motor, postural, and autonomic manifestations: vertigo/dizziness, nystagmus, ataxia, and nausea. These 4 manifestations correlate with different aspects of vestibular function and emanate from different sites within the central nervous system. The diagnosis of vestibular syndromes always requires interdisciplinary thinking. A detailed history allows early differentiation into 9 categories that serve as a practical guide for differential diagnosis: (1) dizziness and lightheadedness; (2) single or recurrent attacks of vertigo; (3) sustained vertigo; (4) positional/positioning vertigo; (5) oscillopsia; (6) vertigo associated with auditory dysfunction; (7) vertigo associated with brainstem or cerebellar symptoms; (8) vertigo associated with headache; and (9) dizziness or to-and-fro vertigo with postural imbalance. A careful and systematic neuro-ophthalmological and neuro-otological examination is also mandatory, especially to differentiate between central and peripheral vestibular disorders. Important signs are nystagmus, ocular tilt reaction, other central or peripheral ocular motor dysfunctions, or a unilateral or bilateral peripheral vestibular deficit. This deficit can be easily detected by the head-impulse test, the most relevant bedside test for the vestibulo-ocular reflex. Laboratory examinations are used to measure eye movements, to test semicircular canal, otolith, and spatial perceptional function and to determine postural control. It must, however, be kept in mind that all signs and ocular motor and vestibular findings have to be interpreted within the context of the patient's history and a complete neurological examination.

Humans↗
PubMed2005

Dissociating cognitive deficits involved in voluntary eye movement dysfunctions in Parkinson's disease patients.

In an attempt to distinguish and define the altered cognitive processes associated with Parkinson's disease (PD), we examine and try to dissociate the components of an effective voluntary saccade: (1) the planning and execution of a voluntary saccade; (2) the suppression of reflexive eye movements; and (3) the working memory processes required. We tested 14 PD patients (off their medications) and 11 control subjects on antisaccade (AS), delayed antisaccade (DAS), and remembered antisaccade (RAS) paradigms. The three tasks required identical responses, each task only differing in a single manipulation for direct comparison--a delay period was added in the DAS, and the target was removed during the delay period of the RAS--allowing us to study the specific cognitive processes involved in the execution of a voluntary saccade. Voluntary saccade response times were longer in the PD group compared to controls on all three tasks, suggesting difficulties in voluntary saccade execution. Furthermore, PD patients showed difficulty suppressing reflexive saccades (increased number of errors in the AS task and increased number of disinhibitions in the DAS task). Finally, our study did not show significant differences in either response time or error rate between the RAS and the DAS tasks for either control subjects or PD patients. In sum, we report evidence for voluntary saccade execution deficits together with problems inhibiting reflexive saccades in Parkinson's disease patients. These findings were correlated with each other and disease severity, suggesting that eye movement measurement may be a useful tool for studying higher cognitive function.

Aged↗