Abstract
Purpose: :
To investigate whether there is a significant correlation between the photopic negative response (PhNR) of the multifocal electroretinogram (mfERG) and the retinal nerve fiber layer thickness (RNFLT) and the visual sensitivity in patients with optic nerve lesions.
Methods: :
Thirteen eyes of 13 volunteers with normal vision and 20 eyes of 10 patients with optic nerve lesions including glaucoma and optic nerve atrophy were tested. The mfERG was recorded with VERIS Science System 5.0.4. The visual stimulus was made up of 37 hexagons in an approximately 40-degree visual field, and testing was done by pseudo-randomly alternating between black (5cd/m²) and white (200cd/m²) on the CRT monitor. The ERGs were band-pass filtered from 1 to 100 Hz. The stimulus frequency was set at 9.41 Hz. Amplitudes of the mfERG PhNR (mfPhNR) were determined at 70 msec and summed for the superior and inferior regions. The RNFLT around the optic nerve head was measured by Cirrus HD-OCT, and averaged for the superior and inferior quadrants. The visual sensitivity (dB) was obtained by standard automated perimetry using the 30-2 programs, and converted to lineal values (1/Lambert) and then averaged for superior and inferior visual fields (linear visual sensitivity).
Results: :
The RNFLT was significantly correlated with the mfPhNR amplitudes recorded from corresponding retinal areas (inferior region: R=0.40, P<0.05; superior region: R=0.64, P<0.0005).There was a significant correlation between the mfPhNR amplitudes and linear visual sensitivity in the superior visual field (R=0.37, P<0.05) with marginal significance in the inferior visual field (R=0.35, P=0.05).
Conclusions: :
Our results indicate that the anatomical or functional losses of retinal neurons in local areas of the retina are a cause of the reduction of the mfPhNR amplitude in optic nerve diseases, suggesting a possibility of regional assessment of retinal ganglion cell function by using the mfPhNR.
Keywords: electroretinography: clinical • nerve fiber layer • visual fields