Photopic negative response of full-field and focal macular electroretinograms in patients with optic nerve atrophy
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To determine alterations of the photopic negative response (PhNR) in the full-field and focal macular electroretinograms (ERGs) of patients with optic nerve atrophy (ONA).
Ten eyes of eight patients, five women and three men with a mean age of 55.1 years, with ONA were studied. Thirty-six age-matched controls were examined using the same protocol. Full-field cone ERGs were elicited by red stimuli on a blue background, and focal ERGs were elicited by a 15° white stimulus spot centered on the macular region.
The a- and b-wave amplitudes of the full-field and focal ERGs of the affected eyes were similar to those of the control eyes. The full-field PhNR amplitudes were significantly reduced in six of ten affected eyes. Four eyes with normal full-field PhNR amplitudes had central scotomas. The focal PhNR amplitudes were smaller than the normal limits in all affected eyes.
The reduction of the full-field and focal PhNR in eyes with ONA indicates that both originate from the retinal ganglion cells (RGCs) and their axons. The findings also indicate that focal PhNR amplitudes can be used to assess focal damages of both the RGCs and their axons in eyes with ONA.
KeywordsERG optic nerve atrophy PhNR photopic negative response
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