How Many People Experience "Phantom Vision" (Charles Bonnet Syndrome)?

Why Does It Happen? (Deafferentation)

The hallucinations are a physiological response to sensory deprivation, not a psychiatric break. This phenomenon is often compared to "phantom limb" pain. When the retina stops sending visual signals to the brain (due to macular degeneration, glaucoma, or cataracts), the visual cortex becomes hyper-excitable. To compensate for the lack of input, the brain begins to fire spontaneously, creating vivid images out of stored memories to "fill the void."

Simple vs. Complex Hallucinations

The visions typically fall into two categories:

Simple - Photopsias, such as flashes of light, geometric grids, brickwork patterns, or tessellated mosaics. These are the most common.

Complex - Fully formed figures, such as people in Victorian era clothing, small animals, gargoyles, or disembodied faces. These images are often silent, static, and fit into the room's perspective (e.g., a cat sitting on the actual sofa).

The Critical Distinction: Insight

The defining medical characteristic of Charles Bonnet Syndrome is insight. Unlike patients with schizophrenia or dementia, a person with CBS usually realizes the images are not real. They may be startled initially, but they can rationalize that "there cannot be a cow in my living room." If a patient believes the hallucinations are real and interacts with them, the diagnosis shifts toward Lewy Body Dementia or other neurological conditions.

Risk Factors

The primary risk factor is the speed and severity of vision loss.

• Acuity - Patients with vision worse than 20/60 are at higher risk.
• Bilateral Loss - It is most common when both eyes are affected, though it can occur with severe one-sided loss.
• Social Isolation - Living alone and having less sensory stimulation can increase the frequency of episodes.