Abstract
Purpose:
To investigate the relationship between the amplitudes and implicit times of N2 of the multifocal electroretinograms (mfERGs) and retinal sensitivity in cases of unilateral glaucoma.
Methods:
Sixteen eyes of 8 patients with unilateral glaucoma were studied. MfERGs were elicited by red stimuli presented on a blue background. Five sites within the central 20 degree (center and four equal sectors) were analyzed. The mfERGs of each site or a combination of all sites were analyzed. The implicit times and amplitudes of N2 and the N2/P1 ratio were compared to the mean retinal sensitivity (dB) of the corresponding sites of the stimulus field of the Humphrey Field Analyzer (HFA) 30-2.
Results:
The average mean retinal sensitivity was -8.45 dB in the glaucomatous eyes and +0.66 dB in the fellow eyes (P<0.01). The average N2 amplitude from the central 5 elements was -1.69 µV in the glaucomatous eyes and -2.03 µV in the fellow eyes (P=0.21). The N2 amplitudes, N2 implicit times, and N2/P1 amplitude ratios in the glaucomatous eyes were not significantly different from that in the fellow eyes. A comparison of the areas with the reduced mean sensitivity to the average of N2/P1 amplitude ratio was -0.62 in glaucomatous eyes and -0.96 in fellow eyes (P<0.05). There was no significant difference in the N2 amplitudes, N2 implicit times, and N2/P1 amplitude ratios between areas with normal and abnormal retinal sensitivities.
Conclusions:
The significant reduction of the N2/P1 amplitude ratios in areas with reduced retinal sensitivity in glaucomatous eyes suggests that the N2 amplitude of the mfERGs receives some contribution from the retinal ganglion cells.
Keywords: 509 electroretinography: clinical