Differential effects of optic media opacities on mfERGs and mfVEPs

ObjectiveTo assess different effects of image degradation that could result from optic media opacities on multifocal retinal (mfERG) and cortical responses (mfVEP).MethodsMonocular flash-mfERGs and pattern-reversal mfVEPs were recorded. MfERG-P1 amplitudes and implicit times and mfVEP root-mean-square values (RMS) and delays were compared for different filter conditions (none, 8% luminance, 50% luminance, 50% luminance plus blur) in a total of ten participants with normal vision.ResultsReducing stimulus luminance down to 50% and 8% reduced mfERG amplitudes to 86% and 42%, respectively, with no significant effect on mfVEP amplitude. Implicit times were increased for mfERGs by 0.9 ms and 6.0 ms, respectively, and for mfVEPs by 1.0 ms and 6.3 ms, respectively. For ‘50% luminance plus blur’ mfERG amplitudes were significantly reduced centrally and enhanced peripherally and delayed by 1.3 ms. MfVEPs were reduced close to noise level independent of eccentricity.ConclusionsDegradation of the retinal image is a potential source of discrepancies between mfERGs and mfVEPs. Image blur suppresses the mfVEP at all locations and changes mfERG topography, resulting in a selective loss of central responses.SignificanceConsidering optic media opacities is of importance for the correct interpretation of mfERG and mfVEP recordings, particularly in elderly patients.

• Image degradation due to optic media opacities is a potential source for misinterpretations of multifocal electrophysiology in vision. • Using filters that mimic optic media opacities, different effects on multifocal electroretinograms and multifocal visual evoked potentials were identified. • It is imperative to take these differential effects into account in clinical electrophysiological routine to avoid misinterpretations of discrepancies between retinal and cortical multifocal recordings.