Abstract
Purpose:
To evaluate the ability of multifocal visual evoked potential (mfVEP) to differentiate between eyes with temporal hemianopia and normal controls and the relationship between mfVEP and visual field (VF) loss on standard automated perimetry (SAP).
Methods:
Twenty-four eyes from 17 patients with permanent temporal VF defects from chiasmal compression (group 1) and 31 healthy eyes from 17 controls (group 2) were submitted to mfVEP using a stimulus pattern of 60 cortically-scaled sectors and SAP. After exclusion of the peripheral 12 sectors, mfVEP response was determined for groups of 24 sectors for the nasal and temporal hemifields and of 12 sectors for each quadrant. VF loss on SAP was calculated as a mean deviation value based on data of the total deviation plot in each quadrant and each hemifield both in logarithmic (dB) and linear (1/Lambert) scales. The two groups were compared using generalized estimated equations. Correlations between mfVEP and VF loss were verified and p level was set at <0.05.
Results:
Mean ± SD mfVEP P1 and N2 amplitudes (μV) from the temporal hemifield were 0.12 ± 0.07 and 0.19 ± 0.13 for group 1, 0.17 ± 0.08 and 0.31 ± 0.16 for group 2 (p=0.054 and p<0.05, respectively). P1 amplitude (mean ± SD) for the superotemporal (ST), inferotemporal (IT), inferonasal (IN) and superonasal (SN) quadrants in group 1 were: 0.11 ± 0.06, 0.14 ± 0.08, 0.19 ± 0.09, 0.15 ± 0.07, respectively. Corresponding values for group 2 were: 0.14 ± 0.06, 0.20 ± 0.10, 0.21 ± 0.10, 0.16 ± 0.07. N2 amplitude (mean ± SD) for the ST, IT, IN and SN quadrants in group 1 were: 0.17 ± 0.12, 0.22 ± 0.15, 0.34 ± 0.15, 0.27 ± 0.12. Corresponding values for group 2 were: 0.26 ± 0.11, 0.36 ± 0.21, 0.37 ± 0.20, 0.29 ± 0.13. Results of P1 and N2 amplitude were significantly smaller in group 1 (p<0.05) for the temporal quadrant measurements, except for ST quadrant P1 amplitude. Likewise no significant difference was observed in mfVEP amplitudes from the nasal measurements. A significant correlation was found between mfVEP amplitude and VF loss in the temporal (p<0.05).
Conclusions:
mfVEP P1 and N2 amplitude parameters were able to differentiate eyes with temporal hemianopia from controls and were significantly correlated with VF loss on SAP. These data suggest that it is a useful technology for detecting visual abnormalities in patients with chiasmal compression.
Keywords: 612 neuro-ophthalmology: diagnosis •
613 neuro-ophthalmology: optic nerve •
758 visual fields