Video-oculography
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Video-oculography (VOG) is a non-invasive, video-based method of measuring horizontal, vertical and torsional position components of the movements of both eyes (eye tracking) using a head-mounted mask that is equipped with small cameras.[1] VOG is usually employed for medical purposes.
Technology
The measurement of the horizontal and vertical components is well established technology which uses pupil tracking and/or corneal reflection tracking and has been widely applied, for example for tracking eye movements in reading. In contrast, the measurement of the torsional component (cyclorotation) is usually considered a computationally more difficult task. Approaches to solving this problem include, among others, polar cross correlation methods and iris pattern matching/tracking.[2][3]
In animal studies, VOG has been used in combination with fluorescent marker arrays affixed to the eye, and it has been proposed that such an array could be embedded into a scleral lens for humans.[4]
Use
VOG techniques have been put to use in a wide field of scientific research related to visual development and cognitive science as well as to pathologies of the eyes and of the visual system.[citation needed]
For example, miniaturized ocular-videography systems are used to analyze eye movements in freely moving rodents.[5]
VOG can be used in eye examinations for quantitative assessments of ocular motility, binocular vision, vergence, cyclovergence, stereoscopy and disorders related to eye positioning such as nystagmus and strabismus.[citation needed]
It has also been proposed for assessing linear and torsional eye movements in vestibular patients[6][7] and for early stroke recognition.[6][8]