Efficacy of N95 amplitude of pattern electroretinogram measured from baseline to N95 trough in the traumatic optic neuropathy

Abstract

Purpose: To investigate the utility of selected pattern electroretinogram (PERG) parameters-including N95 amplitude and N95/P50 ratio, and a BL-N95 amplitude-in the analysis of visual function(s) and for predicting changes in retinal ganglion cell structures in traumatic optic neuropathy.

Study design: A retrospective, observational case series performed at a single center.

Methods: Forty-four eyes from 36 patients diagnosed with optic neuropathy were included. A BL-N95 amplitude was defined as the amplitude measured from baseline to the trough of N95. PERG and pattern visual evoked potential (pVEP) measures were acquired within 1 week after onset of optic neuropathies. To compare functional and anatomical changes, mean temporal peripapillary retinal nerve fiber layer (pRNFL) and average and minimum ganglion cell-inner plexiform layer (GC-IPL) thicknesses were measured using optical coherence tomography.

Results: Thirty-six patients (20 men, 16 women; mean age 37.5 ± 17.6 years) were evaluated. The BL-N95 amplitude was significantly smaller than the N95 amplitude (1.01 ± 0.56 μV and 2.45 ± 1.02 μV, respectively; p < 0.0001). Both the N95 (r = - 0.38, p = 0.010) and BL-N95 r = - 0.32, p = 0.029) amplitudes were significantly correlated with visual acuity. Although P100 latency was not correlated with all PERG parameters, the N95 (r = 0.32, p = 0.032) and BL-N95 (r = 0.41, p = 0.005) amplitudes demonstrated a positive correlation with P100 amplitude in pVEP. PERG parameters, including the N95 and BL-N95 amplitudes, and N95/P50 ratio, were not correlated with pRNFL thickness in optical coherence tomography. Only the BL-N95 amplitude demonstrated a significant correlation with GC-IPL.

Conclusion: The BL-N95 amplitude-measured from baseline to the trough of N95-was valuable in the analysis of visual function(s) and for predicting changes in retinal ganglion cell structures in traumatic optic neuropathy.

Keywords: Electrophysiology; Optic neuropathy; Pattern electroretinogram; Pattern visual evoked potential.