Objective: Nonarteritic ischemic optic neuropathy (NAION) is one of the most frequent causes of sudden visual loss in middle-aged or elderly patients. Although several electrophysiological methods are available for an objective evaluation of the visual deficits, these are not generally used in the assessment of the clinical condition of NAION patients. To evaluate the severity of the optic nerve and retinal damage, electrophysiological tests were performed on 8 patients with NAION.
Methods: Visual evoked potentials (VEPs), scotopic, photopic and flicker electroretinograms (ERGs), multifocal ERGs and pattern ERGs were recorded.
Results: The results demonstrated that the VEPs fairly reliably reflected the visual loss caused by NAION. The VEPs were extinguished in cases with a serious visual acuity loss, while a decrease in amplitude and a lengthening of the P100 latency were observed in cases with good visual acuity and a severe visual field loss and in the nonattacked fellow eye of the patients with monocular involvement. The pattern ERGs failed to show signs of retrograde degeneration. The photopic, scotopic and flicker ERGs, and the oscillatory potentials (OPs) were close to normal in these NAION patients.
Conclusions: Our observations permit the conclusion that electrophysiological methods can provide an objective indication of the clinical condition of these patients. The new data obtained promote an understanding of the pathomechanism of the disease.
Significance: Electrophysiological tests are suitable for monitoring of the progression of the disease in NAION patients.