30-12-2010, 04:38 PM
BY:
Charusree.V.K
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INTRODUCTION
Allows diagnosis of neurologic,ophthalmologic & vestibular disorders.
Conventional ssc s/m employs cubical txr.
Thin ,flat txr.
Convenient in installation,operation & maintanance.
Planar txr increases mobility of ssc s/m, simplifies accomodation in limited clinical space,enables bedside testing,no discomfort etc.
EYE TRACKING
Eye movement,most frequent of all human movements.
Eye tracking is the process of measuring point of gaze or moton of eye relative to head.
Eye tracker measures eye position & eye movements.
Used in research on visual s/m,psychology,cognitive linguistic & in product design.
TECHNIQUES
Electro oculography
Infrared oculography
Image based results
Magnetic eye tracking
ELECTRO OCULOGRAPHY
Measures resting potential of retina.
Potential difference of pairs of electrodes are measured.
Eye acts as a dipole(working principle of electrooculography)
INFRA RED OCULOGRAPHY
Light source is directed to eye.
Measured the amount of light reflected back.
Infra red not influenced by other light.
Spatial resolution 0.1o
Temporal resoluton 1ms.
Drawback is 'blink' of eyes.
IMAGE BASED RESULTS
Automatically extracting eye position from images of the eye.
Measures vertical & horizontal eye movement.
Temporal resolution lower than IR method.
MAGNETIC EYE RACKER
Sensor & txr station.
More accuracy than optical camera.
It gives 3D orientaton.
Main drawback is that,it is wired.
Electrooculogram and tracing displayed by a pen record.
