Abstract
Abstract: :
Purpose: To investigate behavior of the photopic negative response (PhNR) of the Gantzfeld ERG in patients with normal tension glaucoma (NTG). Methods: The scotopic and photopic ERGs according to the protocol of the International Society for Clinical Electrophysiology of Vision were recorded from 30 eyes of 30 patients with NTG and 10 eyes of 10 age-matched normal subjects. The mean deviation of the sensitivity in the NTG patients measured by a static visual field ranged from –0.62 to –10.04 dB. The amplitudes and implicit times of ERGs recorded from the NTG eyes were measured and compared with those from normal controls. Further, we attempted to find the correlation between the PhNR amplitude loss and cupping/disc (C/D) ratio, mean deviation and pattern deviation of visual fields. Results: The averaged PhNR amplitudes were 44.43±7.9 and 28.81±5.9 µV (mean±standard deviation) in the NTG eyes and normal eyes, respectively, with significant difference (p<0.05). There was no significant difference between the NTG eyes and the normals in other ERG parameters. The PhNR amplitude loss did not significantly correlate with the C/D ratio, the mean deviation and pattern deviation of visual fields (R=-0.018, -0.071 and 0.016 for C/D ratio, mean deviation and pattern deviation, respectively). Conclusions: It was demonstrated that the PhNR amplitude is selectively affected in patients with NTG. However, its poor correlation with C/D ratio and severity of visual field defect suggested that the PhNR is not enough sensitive to evaluate progression of local loss of ganglion cells in patients with NTG.
Keywords: electroretinography: clinical • ganglion cells • visual fields