Relationship between the s-wave amplitude of the multifocal electroretinogram and the retinal nerve fiber layer thickness in glaucomatous eyes

Abstract

Purpose: To determine whether a significant correlation exists between the amplitude of the s wave of the multifocal electroretinogram (mfERG) and the retinal nerve fiber layer thickness (RNFLT) in glaucomatous eyes.

Methods: Twenty-three eyes of 23 patients with glaucoma were studied. In all eyes, the severity of the defects in the upper visual field differed significantly from the severity of those in the lower half. Patients having visual field halves with mean deviation (MD) values lower than -5 dB were placed in group A, and patients having visual field halves with MD values greater than -5 dB were placed in group B. The mfERGs were elicited by 37 stimulus elements alternating from white to black in a pseudorandom binary m-sequence at a frequency of 9.4 Hz. The mfERGs in the upper and lower visual field halves were summed to yield upper and lower averaged waves. The GDx variable corneal compensator and optical coherence tomography were used to measure the RNFLT.

Results: The retinal nerve fiber layer was significantly thinner in group A than in group B. There was a significant correlation between the RNFLT and the MD values of visual field defects. The s-wave amplitude was significantly smaller in group A than in group B. The s-wave amplitude also correlated significantly with the MD and the RNFLT.

Conclusion: The significant correlations between the s-wave amplitude and the MD, and between the s-wave amplitude and the RNFLT, indicate that the s-wave receives significant contributions from the retinal ganglion cells and their axons.