Selective Loss of the Photopic Negative Response in Patients With OpticNerve Atrophy

Abstract

Objective To determine how the photopic negative response (PhNR) is altered inpatients with optic nerve atrophy. Methods Ten patients with optic nerve atrophy induced by compression, trauma,or inflammation were examined. There were 6 men and 4 women with a mean ageof 52.4 years. Ten age-matched control subjects were examined with the sameprotocol. Full-field electroretinograms were recorded, and the retinal nervefiber layer thickness surrounding the optic nerve head was measured by meansof optical coherence tomography. Results The amplitudes of the rod, maximum, cone, and 30-Hz flicker electroretinogramsof the affected eyes were not different from those of the corresponding wavesof the contralateral unaffected eyes or control eyes. In contrast, the amplitudeof the PhNR was significantly smaller in the affected eyes than in the contralateral(P = .005) or control (P<.001)eyes. The decrease in amplitude of the PhNR preceded thinning of the retinalnerve fiber layer. There was a significant correlation between the PhNR amplitudeand retinal nerve fiber layer thickness in eyes with optic nerve atrophy (r = 0.879; P<.001). Conclusions Selective reduction and loss of the PhNR amplitude was found in eyeswith optic nerve atrophy, which suggests that the PhNR can be used to evaluatethe function of ganglion cells or their axons.