Dual Mechanisms of Impaired Visual Processing in Glaucoma: Insights From Resting-State and Task-Related EEG

Purpose: To examine both resting-state and task-related electroencephalography (EEG) changes associated with visual processing in glaucoma. Methods: Thirty glaucoma patients (mean age, 63 ± 8.26 years; visual field mean deviation, −15.41 ± 6.34 dB) and 28 age-matched controls (62.86 ± 9.19 years) underwent resting-state EEG for 3 minutes under eyes-open and eyes-closed conditions. Alpha suppression, calculated as the difference between conditions, was assessed as a measure of cognitive state transition capacity. Visual evoked potentials (VEPs) were recorded using a 64-channel EEG system during a checkerboard reversal task under monocular and binocular viewing. Results: Resting-state EEG revealed that significantly reduced alpha suppression was highly specific to a high-alpha subband (10.0–12.9 Hz; P < 0.001), and low-alpha (7.0–9.9 Hz) modulation remained intact in the glaucoma group. Task-related EEG showed delayed latency and reduced amplitude in both P100 and N75–P100 components in the glaucoma group, indicating impaired visual processing. Effect size analysis indicated that P100 amplitude and N75–P100 latency showed the largest group differences, highlighting these as the most prominent cortical changes. Notably, alpha suppression deficits showed no significant correlation with glaucoma severity or VEP parameters, suggesting distinct neurophysiological mechanisms beyond direct visual pathway damage. Conclusions: Both resting-state and task-related EEG measures differed between the glaucoma and control groups, indicating alterations in cortical activity and visual-pathway responses. Specifically, the localized high alpha modulation deficit suggests altered top–down visual network dynamics in glaucoma.