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Updated: Dec 3, 2025
Assessing Binocular Central Visual Field and Binocular Eye Movements in a Dichoptic Viewing Condition
Published on: July 21, 2020
Power spectral density and coherence analysis of eye disease with and without visual hallucination
Sultan Yildiz1, Burak Yulug2, Mehmet Selim Kocabora3
1Regenerative and Restorative Medicine Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey.
Objectives:
Charles Bonnet Syndrome (CBS) is a rare clinical condition which has been defined as complex visual hallucinations (CVH) due to visual loss. This study investigated differences in the EEG power spectral density (PSD) and magnitude-squared coherences between patients with eye disease and hallucinations (VH+), and the control subjects with eye disease without hallucinations (VH-).
Methods:
19 scalp channels EEG was recorded in four VH+ (CBS) and four VH- subjects during an eyes-closed resting condition. Artefact-free epochs were analyzed to obtain PSD values in the delta, theta, alpha1, alpha2, beta1, beta2 and gamma frequency bands. Coherence values were calculated through inter-hemispheric and intra-hemispheric electrodes pairs of interest. All subjects were performed with neuropsychological and behavioral assessments to evaluate cognitive functions.
Results:
The VH + group had increase PSD in theta, beta2 and gamma bands in central, parietal and occipital (O2) areas. The synchronicity was altered particularly in parietal and frontal-parietal regions especially at theta and alpha1 respectively.
Conclusions:
The aberrant activity in occipital and parietal regions suggest the mechanism of CBS. This is a major electrophysiological study of understanding CBS and visual hallucinations.
