Charles Bonnet syndrome and visual acuity

Abstract

A 61-year-old patient suffered from Charles Bonnet syndrome (CBS) while his visual acuity declined, whereas CBS subsided after he became blind. These findings suggest that reduction of visual acuity (dynamic or acute impairment) has a greater impact on the onset of CBS than low visual acuity (static or chronic impairment) per se in some patients. They may also explain why patients with low visual acuity do not always suffer from CBS. Although further studies are required, the present case highlights the importance of the differentiation between lowering and low visual acuity in the etiology of CBS.

Hallucinations Experienced by Visually Impaired: Charles Bonnet Syndrome

“…It was suggested that a decrease in macular edema after treatment resulted in anatomic changes in the fovea. These anatomical changes stimulated visual hallucinations to occur from temporary changes in the quality of vision or through an unknown mechanism that has not been well established 37–39…”

Visual Hallucinations in an Elderly Woman: A Presentation of Charles Bonnet Syndrome?

“…Although decreased visual stimulation is believed to predispose individuals to CBS, persons who are completely blind rarely experience these hallucinations 4 . Therefore, it is believed that it is during acute periods of acute or dynamic lowered visual acuity rather than during chronic or static impairment that an increased incidence of CBS is seen 9 . Differential diagnoses include thalamic or brainstem lesions, Parkinson's disease, Lewy Body Dementia, migraine, schizophrenia, epilepsy, and hallucinogenic induced states.…”

High-Density EEG in a Charles Bonnet Syndrome Patient during and without Visual Hallucinations: A Case-Report Study

“…So far, the most widely accepted mechanism of the emergence of such visual hallucinations refers to the "release phenomenon" suggesting that deafferentation of the visual cortex might lead to cortical hyperexcitability in this area [10,11]. While a few studies, including electroencephalography (EEG) ones, suggest that hyperexcitability in Cells 2021, 10,1991 of 15 the visual cortex of partially blind CBS patients is associated with external visual stimuli (e.g., [12,13]), other studies demonstrate that CBS visual hallucinations can rather arise in the absence of external visual stimuli and, thus, suggest the possibility that spontaneous brain activity could generate conscious percepts (e.g., [14]). Since CBS is relatively rare [15], its investigation is only in the preliminary stages.…”

“…While a few studies, including electroencephalography (EEG) ones, suggest that hyperexcitability in Cells 2021, 10,1991 of 15 the visual cortex of partially blind CBS patients is associated with external visual stimuli (e.g., [12,13]), other studies demonstrate that CBS visual hallucinations can rather arise in the absence of external visual stimuli and, thus, suggest the possibility that spontaneous brain activity could generate conscious percepts (e.g., [14]). Since CBS is relatively rare [15], its investigation is only in the preliminary stages. Only a few studies have investigated the electrophysiological correlates in CBS and none of these investigations has ever used high-density EEG.…”