Objective: To investigate neurophysiological dynamics during a visuocognitive task in glaucoma patients vs. healthy controls. Methods: Fifteen patients with early-stage primary open-angle glaucoma (POAG) and fifteen age-matched healthy participants underwent a “go/no-go” task, monitored with electroencephalography (EEG). Participants had to semantically categorize visual objects in central vision, with animal or furniture as targets according to the experimental block. Results: Early visual processing was delayed by 50 milliseconds (ms) in patients with POAG compared to controls. The patients displayed a smaller difference between animal and furniture categorization during higher-level cognitive processing (at 400-600 ms). Regarding behavioral data, the groups differed in accuracy performance and decision criterion. As opposed to the control group, patients did not display facilitation and a higher accuracy rate for animal stimuli. However, patients maintained a consistent decision criterion throughout the experiment, whereas controls displayed a shift towards worse decision criteria in furniture trials, with higher error rate. Conclusions: The comparative analysis of behavioral and neurophysiological data revealed in POAG patients a delay in early visual processing, and potential high-level cognitive compensation during late, task-dependent activations. Significance: To our knowledge, our findings provide the first evidence of modification in cognitive brain dynamics associated with POAG.