Electrooculography ( EOG ) is a technique for measuring the corneo-retinal standing potential that exists between the front and the back of the human eye. The resulting signal is called the electrooculogram. Primary applications are in ophthalmological diagnosis and in recording eye movements . Unlike the electroretinogram , the EOG does not measure response to individual visual stimuli.
8-408: To measure eye movement, pairs of electrodes are typically placed either above and below the eye or to the left and right of the eye. If the eye moves from center position toward one of the two electrodes, this electrode "sees" the positive side of the retina and the opposite electrode "sees" the negative side of the retina. Consequently, a potential difference occurs between the electrodes. Assuming that
16-423: A design of tonometer, a device for measuring intraocular pressure , in 1959. This groundbreaking instrument was named Mackay-Marg Tonometer, after the developers. This new tool did not require an anaesthetic and thus, for the first time, allowed optometrists to measure intraocular pressure more conveniently. In 1951 Marg described and named electrooculogram for a technique of measuring the resting potential of
24-464: A minimum ("dark trough") after several minutes. When light is switched on, a substantial increase of the resting potential occurs ("light peak"), which drops off after a few minutes when the retina adapts to the light. The ratio of the voltages (i.e. light peak divided by dark trough ) is known as the Arden ratio . In practice, the measurement is similar to eye movement recordings (see above). The patient
32-555: Is asked to switch eye position repeatedly between two points (alternating looking from center to the left and from center to the right). Since these positions are constant, a change in the recorded potential originates from a change in the resting potential. Elwin Marg Elwin Marg (March 23, 1918 – July 15, 2010) was an American optometrist and neuroscientist at the University of California at Berkeley . He
40-667: The Nobel Institute of Neurophysiology, Karolinska Institute , Stockholm, working with Ragnar Granit , future Nobel laureate, in 1956 and 1964, the latter under a Guggenheim Fellowship . He spent the rest of his career at UC Berkeley till his retirement in 1988. First as an instructor in optometry in 1950, then as an assistant professor of physiological optics and optometry in 1951, an associate professor in 1956, and finally full professor in 1962. He published 99 technical papers in various areas. In collaboration with R. Stuart Mackay, an electrical engineer at UC Berkeley, he completed
48-957: The School of Optometry of the UC Berkeley. He entered an undergraduate course in 1938. In 1940, he received an AB in physiological optometry and a Certificate in Optometry. He completed PhD in 1950. During the Second World War , Elwin Marg served as a communications officer in the U.S. Air Force with postings in Ireland , Tunisia , and Italy . During the Korean War he was reinstated for research at Wright-Patterson Air Force Base in Dayton, Ohio . He availed two sabbatical leaves at
56-487: The resting potential is constant, the recorded potential is a measure of the eye's position. In 1951 Elwin Marg described and named electrooculogram for a technique of measuring the resting potential of the retina in the human eye. The eye acts as a dipole in which the anterior pole is positive and the posterior pole is negative. The EOG is used to assess the function of the pigment epithelium . During dark adaptation , resting potential decreases slightly and reaches
64-492: Was the first to receive a PhD from UC Berkeley School of Optometry. It was he who gave the name electrooculogram , a technique for measurement of nerve impulse in the eye. He developed an improved tonometer that avoided use of anaesthetics for the first time in optometrical diagnosis. With his wife he established a non-profit neuroscience organisation, the Minerva Foundation in 1983. Elwin Marg studied at
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