Abnormal Rod Photoreceptor Function in Retinitis Pigmentosa
Over the years, a clinical diagnostic protocol has evolved for the full-field electroret-inogram (ERG) and recent attempts to standardize the protocol (1) have largely been successful. As part of the standard ERG protocol, a single rod flash is obtained from a patient in a full-field dome. The protocol response is useful for establishing the retinal basis of visual loss, and can provide information on the rate of progression in hereditary retinal degeneration. However, the peak-to-peak amplitude of a single response is a snapshot of rod behavior that reflects amplitude at a single point in time following a single stimulus intensity. The purpose of this paper is to show that considerably more information about rod function can be obtained by analyzing the dynamic behavior of rod responses over both time and intensity. In particular, we have developed two approaches for analyzing the human rod photoresponse. Both approaches require high intensity stimuli to reveal the underlying photoreceptor component of the ERG and both can be used to test specific hypotheses regarding mechanisms of degeneration in hereditary retinal diseases.
KeywordsRetinitis Pigmentosa Test Flash Autosomal Dominant Retinitis Pigmentosa Outer Segment Disk Nonnal Subject
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