1/12/2024 0 Comments Rgc cells pupil measurement rgcThese inner-retina-sensitive ERG components have also been shown to be altered in clinical and experimental studies of glaucoma. More recently, different laboratories discovered that under particular luminance-stimulus conditions, the Flash-ERG displays components (positive Scotopic Threshold response, pSTR negative Scotopic Threshold Response, nSTR Photopic Negative Response, PhNR Oscillatory Potentials, OPs multifocal ERG, mfERG) that may reflect electrical activity originating in the proximal retina. These studies sparked a considerable wave of interest resulting in a large number of clinical and experimental reports that the PERG is altered in glaucoma, even at early stages. This crucial experiment has been repeated many times in different mammals including nonhuman primates and rodents (rats and mice), with similar results. In 1981, however, a study in the cat ( Maffei and Fiorentini, 1981) showed that the ERG in response to contrast-reversing patterns at constant mean luminance (Pattern-ERG, PERG) was abolished after section of the optic nerve that retrogradely killed RGCs leaving outer retina neurons and the standard Flash-ERG intact. The use of electrophysiology in glaucoma models may be facilitated by specifically designed instruments that allow high throughput, robust assessment of electrophysiological function.įor a very long time, a well-established notion has been that the ERG did not reflect electrical activity of retinal ganglion cells (RGCs)( Riggs, 1986). Neuroprotective strategies could be tested based on enhancement of baseline electrophysiological function that results in improved RGC survival. Electrophysiological assessment of RGC function appears to be a necessary outcome measure in experimental glaucoma models, which complements structural assessment and may even predict it. It is not yet known which of these components is most sensitive to glaucomatous damage. Under particular luminance-stimulus conditions, the Flash-ERG displays components that may reflect electrical activity originating in the proximal retina and be altered in some experimental glaucoma models (positive Scotopic Threshold response, pSTR negative Scotopic Threshold Response, nSTR Photopic Negative Response, PhNR Oscillatory Potentials, OPs multifocal ERG, mfERG). In glaucoma models, the PERG can be altered before histological loss of RGCs PERG alterations may be either reversed with moderate IOP lowering or exacerbated with moderate IOP elevation. The best understood technique is the Pattern Electroretinogram (PERG) in response to contrast-reversing gratings or checkerboards, which selectively depends on the presence of functional RGCs. The function of retinal ganglion cells (RGCs) can be non-invasively assessed in experimental and genetic models of glaucoma by means of variants of the ERG technique that emphasize the activity of inner retina neurons.
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