Scotopic multifocal visual evoked potentials

Publication date: Available online 31 December 2018

Source: Clinical Neurophysiology

Author(s): D. Muranyi, F. Kramer, A. Herbik, M.B. Hoffmann

Abstract

Objective

To investigate the scope of scotopic multifocal visual evoked potentials (mfVEP_S) for the assessment of scotopic visual fields.

Methods

Pattern-reversal mfVEP for photopic (mfVEP_P) and scotopic conditions (mfVEP_S; 0.003 cd/m2) were recorded from 36 visual field locations of a circular checkerboard pattern (25° radius) in 9 participants with normal vision. MfVEP_P were recorded with a conventional central fixation cross, mfVEP_S were recorded (i) with (mfVEP_S+) and (ii) without (mfVEP_S-) an additional fixation aid. Latency shifts were determined using cross-correlations, mfVEP magnitudes were analysed in an eccentricity dependent manner using signal-to-noise ratios (SNRs).

Results

In comparison to mfVEP_P, mfVEP_S- and mfVEP_S+ were delayed by 101 ms and 97 ms, respectively, and had smaller signal-to-noise-ratios (SNR). Both mfVEP_S were reduced down to noise level in the center and also severely reduced for the most peripheral stimulus eccentricity used. The visual-field-coverage for the paracentral eccentricities of mfVEP_S+ and mfVEP_S- was 76% and 65% [4°-9°], respectively, and 79% and 66% [9°-16°].

Conclusions

MfVEP_S were delayed compared to mfVEP_P and demonstrated the expected central response drop-out typical for scotopic vision.

Significance

MfVEP_S may hold promise of an objective, spatially resolved visual field test which motivates testing it in patients with diseases affecting scotopic vision.

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