Comparison of visual evoked potential variability in eyes affected by optic neuritis and fellow eyes

This study compared the variability of visual evoked potential (VEP) in response to stimulation of eyes affected by unilateral optic neuritis with that of fellow (non-affected) eyes.

Pattern-reversal VEP (PVEP) and motion-onset VEP (MVEP) recordings from thirty-six subjects with unilateral optic neuritis at different intervals from disease onset were retrospectively evaluated, and differences in the following parameters were compared: signal‒to‒noise ratio (SRN), interquartile range of the response jitter (jitter IQR), and number of trials corresponding to the average response (corresponding N).

In the PVEP recordings, the P1 peak times of the fellow eyes were significantly shorter than those of the affected eyes (Cohen's d = -1.470, p < 0.001). P1 amplitudes were significantly greater in fellow eyes (d = 1.17, p < 0.001). Significant differences were found in the SNR (d = 0.782, p < 0.001), jitter IQR (d = -0.874, p < 0.001), and corresponding N (d = 0.700, p < 0.001). MVEP presented significantly shorter N2 peak times in fellow eyes than in affected eyes (d = 0.840, p < 0.01) and significantly greater amplitudes (d = 0.494, p = 0.002). There was a significant difference in the SNRs (d = 0.440, p = 0.01) and corresponding N values (d = 0.415, p = 0.01). There was no difference in the jitter IQR (d = 0.143, p = 0.230).

The increased variability in eyes affected by optic neuritis compared with fellow eyes (in particular, in pattern-reversal VEP, which predominantly represents the activity of the macular-papillary fibers of the optic nerves) may represent important pathophysiologic features and may add valuable information to diagnostics via VEP examinations.