What is Charles Bonnet syndrome?

Lens adapted to this topic: Mechanisms under debate

The serious dissent is mainly about explanation, not whether the syndrome is real. Computational and neuroscience research argues that simple ‘the brain fills in missing input’ accounts may be incomplete: hallucinations have phenomenological features requiring reality monitoring and may involve altered cortical activity. These approaches remain models and research findings rather than a replacement for the established clinical description.

• A 2023 philosophical analysis argues that the strong-prior predictive-processing model does not fully explain the phenomenology of Charles Bonnet hallucinations without adding reality monitoring.
• A computational model treats vivid hallucinations after vision loss as evidence that the cortex can generate rich internal visual representations.
• A 2025 multimodal study found altered visual-cortical activity in people with Charles Bonnet syndrome compared with people who had eye disease without hallucinations.
• These studies refine or challenge proposed mechanisms; they do not dispute the established association between sight loss and visual hallucinations.

Featured sourceExplanatory power by vagueness. Challenges to the strong prior hypothesis on hallucinations exemplified by the Charles-Bonnet-Syndromeexa.ai3 sourcesView sources