Search Results

Measuring temporal characteristics of saccadic refixation responses when viewing lateral visual stimulus and identifying the individual time delays of moving the eyes toward the stimuli.

The Saccadometer system measures eye movements in horizontal axis with temporal 1kHz and spatial resolution < 5 arc min. The system incorporates a built in visual target presentation using miniature laser projectors mounted on the sensor forehead plate. Saccadometer Plus is equipped with three red laser projectors with 10° separation. Saccadometer Advanced has additional extra green laser and it allows to perform more complex saccadic task. Information about eye movement is acquired by analyzing the infrared light reflected from eye orbit. The left and right eve orbit are illuminated by two infrared LEDs, providing eve surface irradiance below 1mW/cm-(operating condition). Due to the conjugacy and synchronicity of the saccadic eye movements, the rotation of left and right eyes, can be added and averaged. The inner canthi of the left and right eyes are illuminated with the low intensity IR. The difference between the amounts of IR reflected back from the eye surfaces toward the photodetecting circuitry, carries the information about the eye position changes. The eye landmarks are taking part in generation of the eye movement signal. The corneal bulge and the limbus (the border between darker iris and white sclera). Main contributor to the eye movement signal is the corneal bulge. Being the relative eye position measurement system, it requires to define the initial eye position. It means that at the beginning of every measurement, a steady eye fixation point needs to be provided. In Saccadometer the central fixation target serves this purpose. The Saccadometer Plus and Saccadometer Advanced systems are composed of: - proprietary hardware and firmware, enclosed in - examination control unit with 2 x 1.5V AA batteries, and the - eye movement sensor with integrated miniature laser spot projectors - proprietary software application LatencyMeter. - optical fiber to USB data transmitter