A Study of the Prevalence of the Charles Bonnet Syndrome and Associated Factors in 500 Patients Attending the University Department of Ophthalmology at Nijmegen
Published online by Cambridge University Press: 02 January 2018
The aims were to determine the prevalence of the Charles Bonnet syndrome (CBS) in low-vision patients and analyse possible associated ophthalmic and sociodemographic factors.
A semi-structured interview on visual hallucinations was given to 300 adult low-vision patients and 200 elderly general ophthalmic patients. Positive cases were examined with the Geriatric Mental State Schedule and the Mini Mental State Examination. Diagnostic criteria were as follows: complex, persistent, or repetitive visual hallucinations; full or partial retention of insight; no hallucinations in other modalities; and no delusions. Ophthalmic and sociodemographic data were gathered for all patients.
The prevalence of CBS in low-vision patients was 11%. CBS was significantly associated with an age over 64 years and a visual acuity in the best eye of 0.3 or less. No significant associations with ophthalmic diagnoses, patient sex, marital status, or social circumstances were found.
Our findings support association of CBS with sensory deprivation and advanced age.
1. Visual acuity was measured in each eye separately by the Snellen chart, on which rows of letters of different standard sizes are printed. The patients are asked to read the letters from a fixed standard distance. Visual acuity is expressed as the ratio of the distance at which the patient is still able to distinguish the letters to the distance at which a person with normal vision is capable of doing so. Example 1: a patient is able to read letters from a distance of 5 m which normally could be read from this distance; visual acuity is expressed as 5/5 or 1 (normal). Example 2: a patient is only able to distinguish letters from a distance of 5 m which normally could be read from a distance of 25 m; visual acuity is expressed as 5/25 or 0.2.
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