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At least 19 recordsLinked to original sources
PubMed1991

[Correction of EOG with eye movement measured by the eye mark recorder system].

The electrooculogram (EOG) is usually necessary for the subject to fixate two targets alternately at a fixed visual angle. However, in the patients with poor vision, it can be difficult to fixate exactly. In such case, the results can be improved by using both the measurement of real eye position and the measurement of EOGs in combination. In this study, we measured subject's eye position simultaneously with the potential changes around his eyes as the subject pursued alternately two on-and-off visual targets which were horizontally placed on the cylindrical screen at a regular visual angle in front of his eyes. The EOG is obtained from those potential changes. If the difference between the target position and the fixating point can be calculated from the net eye movement measured with an eye camera, the error potential can be derived from this difference. Therefore, exact potential changes are obtained by correcting the measured potentials with the above error potentials. The authors were able to confirm that the potential changes were approximately proportional to the amplitude of saccadic eye movements within about 30 degrees in front of the eyes. Therefore, the simultaneous measurement of the potential changes and the eye position enable measurement of EOG without pursuing the targets by transforming the measured potentials into the exact values corresponding to the constant amplitudes of saccades.

Electrooculography↗
PubMed2002

Neurophysiological markers of vulnerability to schizophrenia: sensitivity and specificity of specific quantitative eye movement measures.

Eye-tracking deficits in schizophrenic patients and relatives have generated interest in using eye movements to mark schizophrenia liability. Efforts to develop specific quantitative measures have provided insight into the nature of the deficit and suggested what underlying neurophysiological mechanisms are involved. This study used receiver operating characteristic curve analyses to evaluate and compare the sensitivity, specificity, and overall accuracy of predicting disease liability using single and combined specific and global quantitative measures. Results indicate that measures of predictive pursuit and leading saccades significantly increased predictive accuracy compared with traditional global measures. Combining specific measures provided greater predictive accuracy compared with single measures. Implications for the use of specific eye movement measures to define schizophrenia-related phenotypes in genetic studies are discussed.

Adult↗
PubMed1992

An adjustment to eye movement measurements that compensates for the eccentric position of the eye relative to the center of the head.

We describe a procedure for modifying horizontal eye movement measurements in a way that effectively removes signal contributions due to the eccentric location of the eyes relative to the center of rotation of the head. This procedure helps standardize measured signals so that data collected under different experimental conditions and from different subjects may be compared directly. We also present techniques for accurately determining specific parameters of head geometry that are required by the procedure. This method may be used for modifying eye movement responses to visual target motion, head motion, or both, and does not assume continual fixation of the visual target. Also, this method may be employed when either curved (iso-distance) or flat display screens are used for presenting the visual stimuli.

Eye↗
PubMed1993

Benzodiazepine pharmacodynamics: utility of eye movement measures.

The utility of several measures of saccadic and smooth pursuit eye movements as benzodiazepine pharmacodynamic measures was explored in 24 psychiatrically and medically health control subjects. Measures of sedation and memory impairment were also included. Subjects received four logarithmically increasing doses of intravenous diazepam at 15-min intervals on 1 day resulting in monotonically increasing plasma diazepam levels, and placebo on another day in random order 1 week apart. Measures were collected twice at baseline, once after each dose of diazepam/placebo and twice more, 15 and 30 min after the last dose. Peak saccadic velocity and smooth pursuit gain showed the greatest overall and dose-dependent drug effect among eye movement measures. Although effect sizes at the highest dose for memory impairment and self-rated sedation were comparable to these two measures, reliability (i.e., placebo-day fluctuation) with these measures was considerably poorer. Log-linear pharmacodynamic modeling was used to calculate the effective dose (ED30) or concentration (EC30) required to reduce saccadic velocity or pursuit gain by 30%. Almost all (23/24) subjects had linear and easily interpretable plots for saccadic velocity, while a majority (19/24) of subjects had interpretable plots for smooth pursuit gain. The distribution of ED30 and EC30 values showed a wide range of sensitivities to diazepam. These findings suggest that saccadic velocity and smooth pursuit gain are sensitive, reliable, quantitative benzodiazepine pharmacodynamic measures.

Adolescent↗
PubMed1984

A modified lateral eye-movement measure, the right hemisphere and creativity.

The relationship between direction of gaze and creativity was studied using a modified measure of lateral eye movement which recorded the total time of gaze rather than initial direction of gaze only. Twelve subjects were presented the Uses Test and the Remote Associates Test orally while direction of gaze was monitored. Analysis yielded a high positive correlation between left gaze and upward gaze for the Uses Test scores while directional gaze did not correlate with Remote Associates Test performance. These findings would have been obscured if the conventional method of recording lateral eye movements had been used.

Creativity↗
PubMed2003

EMMA--an eye movement measurement and analysis system.

A system has been developed for stimulation, recording and analysis of a wide range of eye movements. Eye movements are stimulated with an LED bar or a video projector under the control of a PC. The eye movements are measured using a scleral reflection technique (IRIS instrument), and sampled and stored on a PC. A range of tests have been developed to measure saccadic and smooth pursuit eye movements. A variety of tools have been developed to assist in the analysis of the data. Several research studies have ably demonstrated the utility and versatility of the system.

Equipment Design↗
PubMed1991

Digitally calibrated eye movement measurement system.

A less expensive instrumentation alternative to record horizontal eye movements is presented in the form of a feasibility study. Currently, there are several techniques used to accurately measure eye position for research purposes. To implement these techniques, significant financial resources are required. The proposed technique costs less than $3000.00 and is based upon the limbus position technique. A linear charged coupled device (CCD) image array sensor and a biconvex lens are used to determine the position of the pupil. The self scanned CCD array is controlled by four analog clock signals generated from digital logic. The CCD video output signal is converted to a TTL compatible signal. The TTL signal is used to create a digital number based upon the limbus image formation upon the CCD pixels. This digital number is processed using standard signal acquisition techniques and is recorded on the hard drive disk of an IBM PC/AT compatible system. The C programming language is used to acquire the data and control calibration of the system. FORTRAN software is used to implement digital signal processing algorithms and estimate eye position.

Calibration↗
PubMed1959

Photoelectric technique for measuring eye movements.

By the system described, the movement of a stimulus and the correlated tracking movements of the eye are recorded simultaneously. The technique for measuring the eye movements consists of detecting and amplifying by photomultiplication the total amount of light passing through a small slit upon which is imaged a small portion of the light-dark field represented by the iris and sclera of the eye. This total amount of light varies directly with the angular position of the eye.

Electronics↗
PubMed1985

A soft contact lens search coil for measuring eye movements.

A five turn coil of magnet wire sandwiched between two soft contact lenses served as a magnetic search coil to measure horizontal and vertical eye movements in humans. The lens was adhered to the eye for 35 min by periodically misting the eye with distilled water; during this time the records of eye position showed that the lens remained firmly attached to the eye. Using this sensor, no topical anesthetic need be applied and the lens can be worn for an extended period of time without increasing intraocular pressure.

Contact Lenses, Hydrophilic↗
PubMed1994

Measuring eye movements in Graves ophthalmopathy.

BACKGROUND: The current grading of class IV (extraocular muscle involvement) of the NO SPECS classification for Graves ophthalmopathy is subjective and, in practice, virtually limited to three grades (grade c rarely occurs). The subjectiveness results in a high degree of observer disagreement, as illustrated by kappa values of 0.48 to 0.64 for the agreement between the authors in grading of class IV changes in 13 patients. METHODS: The authors investigated the significance of a quantitative approach in assessing eye motility and modified a hand perimeter to measure the monocular eye movements in degrees. RESULTS: The mean maximal excursions in the four main directions of gaze, obtained with this device in 40 healthy control subjects (5 men and 5 women from each decade between 20 and 60 years of age), were as follows: elevation = 34 degrees, depression = 58 degrees, adduction = 48 degrees, and abduction = 46 degrees. The ductions showed an age-related decline. The intraobserver and interobserver variations were assessed in 12 and 18 patients with Graves ophthalmopathy, respectively, by calculating the coefficients of repeatability, which varied from 5 degrees to 8 degrees. The authors compared the current grading of NO SPECS class IV with quantitative measurements of elevation in 11 patients by calculating the kappa values for agreement. These were found to be 0.57 and 0.80, respectively. CONCLUSIONS: The quantitative measurement of eye movements with a modified perimeter appears to be precise and reproducible. In addition, it should replace the current grading of the extraocular muscle movements of Graves ophthalmopathy patients in the NO SPECS classification, which is less reliable, as evidenced by a higher degree of observer disagreement.

Adult↗
PubMed1995

3-D eye movement measurements on four Comex's divers using video CCD cameras, during high pressure diving.

Previous studies have shown the vulnerability of the vestibular system regarding barotraumatism (1) and deep diving may induce immediate neurological changes (2). These extreme conditions (high pressure, limited examination time, restricted space, hydrogen-oxygen mixture, communication difficulties etc.) require adapted technology and associated fast experimental procedure. We were able to solve these problems by developing a new system of 3-D ocular movements on line analysis by means of a video camera. This analyser uses image processing and forms recognition software which allows non-invasive video frequency calculation of eye movements including torsional component. As this system is immediately ready for use, we were able to realize the subsequent examinations in a maximum time of 8 min for each diver: oculomotor tests including saccadic, slow and optokinetic traditional automatic measurements; vestibular tests regarding spontaneous and positional nystagmus, and reactional nystagmus to the pendular test. For pendular induced nystagmus we used appropriate head positions to stimulate separately the lateral and the posterior semicircular canal, and we measured the gain by operating successively in visible light and complete darkness. Recordings were done during a simulated onshore dive to an ambient pressure corresponding to a depth of 350 m. The above examinations were completed on the first and last days by caloric tests with the same video system analyser. The results of the investigations demonstrated perfect tolerance of the oculomotor and vestibular systems of these 4 divers thus fulfilling the preventive conditions defined by Comex Co. We were able to overcome the limitations due to low cost PC computer operation and cameras (necessity of adaptation to pressure, focus difficulties and direct light exposure eye reflexions). We still have on line accurate measurements even on the torsional component of the eye movement. Due to this technological efficiency we also present some mathematical aspects of the software.

Adult↗