Multifocal ERG reveals long distance effects of a local bleach in the retina.
To examine the distribution of ERG-activity in the central visual field after local bleaching of the fovea, multifocal electroretinograms were recorded in eight normal volunteers before, during and after recurrent light exposure. During bleaching (90% bleached pigment), the response density (scalar product) of the foveal area (0-2 degrees eccentricity) decreased from 10.7 +/- 3.5 to 4.1 +/- 1.9 nV/degree2 (P < 0.001). The average activity in the extrafoveal macular area was unchanged, while the amplitudes were frequently (in 53 of 54 areas) enhanced at 5-30.5 degrees eccentricity. Here the average response density changed from 3.1 +/- 0.9 to 3.5 +/- 1.0 nV/degree2 (P < 0.001). A fast recovery of foveal responses after cessation of bleaching occurred. Besides a strong decrease of response in the directly bleached area, local bleaching led to enhanced activity mainly 3-27 degrees distant from the bleached area.
Kretschmann
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U
Department for Pathophysiology of Vision and Neuro-Ophthalmology, University Eye Hospital, Tuebingen, Germany.
Tornow
R P
RP
Zrenner
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E
D000221:Adaptation, Ocular / Q000502:physiology*; D000328:Adult; D004596:Electroretinography; D005584:Fovea Centralis / Q000502:physiology; D006801:Humans; D008027:Light; D012160:Retina / Q000502:physiology; D013997:Time Factors; D014794:Visual Fields