Purchase this article with an account.
Yuan-Pin Lin, Yijun Wang, Tzyy-Ping Jung, Felipe A Medeiros; Using Multifocal Steady-State Visual Evoked Potentials for Objective Assessment of Visual Field Loss: A Pilot Study. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5126.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To develop an objective electroencephalogram (EEG)-based brain sensing technique for visual-field examination by using high-density EEG to associate the dynamics of multifocal steady-state visual-evoked potentials (mfSSVEPs) with visual field defects.
The working hypothesis was that presenting multiple frequency-tagged flickering (alternating black/white) sectors in the monocular visual field, a sector(s) corresponding to a visual field deficit(s) would be less perceivable or unperceivable and thereby would have weaker SSVEP amplitude, compared to other normal visual spots. To test the hypothesis, we designed a layout of visual stimuli consisting of 20 sectors in three concentric rings (subtending 6°, 15°, and 25° in the visual field). All sectors flickered concurrently at different frequencies ranging from 8 Hz to 11.8 Hz with a frequency resolution of 0.2 Hz. The visual field DEFICIT condition was mimicked by replacing the 9 Hz sector (the 0-45° patch in the middle ring) with a black patch in contrast to the CONTROL condition in which all 20 sectors flickered concurrently. The EEG data from five normal participants were recorded using a 128-channel BioSemi ActiveTwo EEG system during visual stimulation (5 seconds per trial, 100 trials for each condition).
The empirical results showed that four of five participants consistently exhibited a significant deterioration of the 9 Hz SSVEP amplitude in the DEFICIT condition compared to the CONTROL condition (Figure). The inconsistency from one participant was likely attributed to the absence of gaze-attentive fixation to the visual stimulus according to his self-report after the experiment.
These preliminary results demonstrated that visual field deficit mimicked by disabling the 9 Hz sector did result in significant SSVEP attenuation at the corresponding frequency. Furthermore, this pilot study suggests that the dynamics of mfSSVEP amplitude is capable of serving as an objective biomarker to assess potential visual field deficits in conditions such as glaucoma.
This PDF is available to Subscribers Only