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PETER GOURAS, RALPH D. GUNKEL, JAMES JONES; Spatial Differences in the Human ERG. Invest. Ophthalmol. Vis. Sci. 1962;1(3):333-339.
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© ARVO (1962-2015); The Authors (2016-present)
Electronic computer techniques have been employed to enhance the recording of the ERG so that a sensitivity of 1µv is attainable. A study of ERG profiles to 1 degree red and blue light stimulation of both normal and pathologic eyes indicates that: The normal ERG profile shows a high red sensitivity centrally that diminishes 15 degrees of either side of the horizontal meridian. The normal profiles to blue light show no significant spatial difference. At threshold the positive peak of the normal response to red light occurs at approximately 50 msec. The positive peak of the normal blue response is longer than 90 msec, even at amplitudes much greater than the red response. The former resembles the x-wave and the latter the b-wave of the higher amplitude ERG. Damage to the macula produces a lowering of the central response in proportion to the extent of the lesion and is more detectable with red light. Advanced retinopathies with markedly elevated ERG thresholds can be differentiated by spatial, temporal, and threshold differences in their summed low-level responses to chromatic stimulation.
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