The Studieg on Vertical Eye Movement Disorders: Vertical Saccadic Velocity Measurements

This study is concerned with human vertical saccadic systam to various visual stimulus. A system is described fer the recording and analysis of corrective movements and the angular velocities asscciated with 10 degrees and 20degrees vertical saccades. Recordings wsre made with photoelectric IR reflection method and the saccades were induced by a target system which operates on non-predictable manner. Statistical results for average peak veIomnes of right eye are given for a group of 4 normal subjects and compared with horizontal saccades. Most of corrective movements were categorized to saccadic and glissadic and magnitude of corrective errors were within 1 degree and 2 degrees and showed 20% production rate. The peak velccity statistics showed as 280 and 440 deg/s associated with 10 degrees and 20 degrees vertical movement and downward values were slightly faster than upward movements. Our results were compared with horizontal saccades and discussed the possibility of research and clinical tool that could be used on a large number and variety of patients.

Some Observations of the Human Saccadic Visual Tracking System to the Successive Stimuli

This study aims to ascertain the human saccadic visual tracking characteristics by measuring the eye movement to the double-step stimuli. Responses to simple step and double-step target motions were measured where the target mode and stimulus durations were randomized. To measure the eye movement the Photo-electric Eye Monitor was constructed based on limbus tracking. The results indicate that observers represented two kind of responses (A-or B-type) depending upon the stimulus duration. The percentage of occurrances increased as the stimulus duration increased from 50 to 200 msec. When the subject responded to both target motions, the reaction time of the second saccade was shorter than that of the first. The successive visual information is to change continuously the reaction time or cancel the initial saccade. Our results revealed that parallel data processing characteristics of the visual tracking systems and the saccadic decision-makings are influenced by the temporal relationships.

Saccadic Eye Movement Characteristics to the Double-Step Stimuli

The saccadic reaction times to the double-step stimuli were studied in three human subjects to ascertain the saccadic visual tracking characteristics. Responses to simple step and double-step target motions were measured where the target mode and stimulus durations were randomized. To measure the eye movement the Photo-electric Eye Monitor was constructed based on limbus tracking. The results indicate that observers represented two kind of responses (A-or B-type) depending upon the stimulus duration. The percentage of occurrances increased as the stimulus duration increased from 50 to 200 msec. When the subject responded to both target motions, the reaction time of the second saccade was shorter than that of the first. The successive visual information is to change continuously the reaction time or cancel the initial saccade. Our results revealed that parallel data processing characteristics of the visual tracking systems and the saccadic decision-makings are influenced by the temporal relationships.

Photo-electric Limbus Tracking System Measuring Eye Movements

A new method is described which uses photo-electric matrix method to measure two-dimensional eye movements. This system is composed of the detector unit (monitor), matrix and correction circuits and stimulus generator. A light and small detector unit attached to the modified trial frame transduces positional informations and can be achieved head-mounting. The instrument operates in the infrared, so that it does not interfere with normal vision, and over a two-dimensional visual field to +/-15 degrees. A system for generating a fixed target whose velocity, displacement, form, intensity, and other characteristics can be varied systematically also is described. The operating procedures are described and operating records are shown. Electrical and optical modifications of the present system will make possibIe the measurement of more smaller movement of the eye. Extensions and improvement of the technique of measurement are discussed briefly.

A Review for the Eye Movement Measuring Systems

The purpose of this review is to examine the ways in which eye position and eye movements are measured in order to justify the choice of method for the study concerning the eye movement control systems. The oculomotor control systems were reviewed previously as a viewpoint of measuring objects. Because of the different aspects of eye movement which have been considered, various techniques have been developed-each having its own characteristics of range, sensitivity, bandwidth, stability and ease of application. This study is directed at discussing the pros and cons inherent in a basic method of measurement and to indicate the interesting historical development of oculography as new technologies were employed. Various methods are summarized and photo-electronic method(Limbus tracking technique) was chosen which is most available for the future experimentation.