gms | German Medical Science

102. Jahrestagung der DOG

Deutsche Ophthalmologische Gesellschaft e. V.

23. bis 26.09.2004, Berlin

Recognition of artificial visual field defects using the multifocal VEP

Meeting Abstract

  • corresponding author R. Gockeln - Department of Ophthalmology, Hannover Medical School
  • P. Scholz - Department of Ophthalmology, Hannover Medical School
  • M. Meyer - Department of Ophthalmology, Hannover Medical School
  • L. Blomberg - Department of Ophthalmology, Hannover Medical School
  • R. Winter - Department of Ophthalmology, Hannover Medical School

Evidenzbasierte Medizin - Anspruch und Wirklichkeit. 102. Jahrestagung der Deutschen Ophthalmologischen Gesellschaft. Berlin, 23.-26.09.2004. Düsseldorf, Köln: German Medical Science; 2004. Doc04dogSA.12.02

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Veröffentlicht: 22. September 2004

© 2004 Gockeln et al.
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The objective detection of local visual field defects using the multifocal m-sequence technique has reently been described in many studies. To evaluate the ability of the multifocal VEP (mfVEP) to detect defects in the stimuls array was the objective of this study.


Monocular mfVEPs were recorded in 44 normal subjects (mean: 28 J., SD: 5,7J.) with a multichannel recording system. The electrodes were placed following previous studies, 4 cm above the inion (Oz) and 4 cm lateral to the location 1 cm above the inion (OL & OR) and were referenced to an electrode at the inion (In). In addition to the bipolar (occipito-occipital) arrangement we used simultaneously a monopolar (occipito-frontal, Oz-Fz) arrangement. Signals were amplified by band-pass filtered 1 to 70 Hz and sampled at 911 Hz. The mfVEP stimulus, a cortically scaled dartboard with a diameter of 50°, was produced with RetiScan" software (Roland Consult, Germany). The stimulus array consisted of 60 sectors, each with 16 checks, 8 white (200 cd/m2) and 8 black (1 cd/m2). Different-shaped masks (cirular & sector masks) were used to occlud various parts of the stimulus display for comparison with the corresponding locations of the full-field mfVEP. Differeces in the mean of the mfVEP parameters recorded from different visual field loci and from different stimulus arrays were evaluated using the Student´s t-test and verified by Mann-Whitney test.


Only masks that covered sectors in the central 25° stimulus display caused a significant reduction in signal (P<0.01). Different-shaped masks of about 2° diameter were detectable using a 60-sector array only when they fully covered a stimulus sector. Detection of the occluded sectors was better, but marginal for some masks and depends on the location of the masks, with additional channels and electrodes (e.g. OL & OR, Oz-Fz). The monopolar arrangement (Oz-Fz) clearly demonstrated a better spatial resolution of the central visual field (up to 6 or 10°), whereas the peripheral visual field was better presented by using the bipolar arrangement of the electrodes.


Masking the stimulus display is not equivalent to having a pathologic scotoma, but it demonstrates the best possible spatial resolution of the mfVEP. In the present study, the spatial resolution of the mfVEP responses correlated well with the topographical layout of stimulus screen. The finest spatial resolution was found in the central visual field compared to the peripheral visual field.