Epidemiology and phenomenology of the Charles Bonnet syndrome in low-vision patients.

Background: The occurrence of visual hallucinations in visually impaired people without mental impairment is known as Charles Bonnet Syndrome (CBS). To date, the prevalence of CBS has been reported with high variance. The present study aims at evaluating the prevalence of CBS among low-vision patients.

Methods: From March 2018 to February 2022, 194 patients with a visual acuity ≥ 0.5 logMAR approached the low vision section of the Eye Clinic Sulzbach. Of these, 50 patients were found eligible, agreed to participate in the study and were screened for CBS. The course of the disease, its phenomenology and characteristics, the circumstance of onset, the ability to manipulate and resolve the hallucinations, and the psychosocial aspects of CBS were investigated.

Results: 26% of patients with low vision suffered from CBS. Women did not suffer from CBS significantly more often than men. Often, insight into the unreality of the images is not achieved immediately. Patterns or so-called "simple" hallucinations occurred just as frequently as other types of images such as people, body parts or faces. The most frequent images were animals. Visual hallucinations, lasting only for seconds in most cases, occurred more frequently during the day and in bright surroundings. All patients experienced the hallucinations exclusively with their eyes open. The hallucinations generally did not move with the eyes. Many sufferers did neither communicate about their hallucinations nor consult any physician.

Conclusions: CBS among low-vision patients is common. Its prevalence constitutes clinical relevance. Future management of CBS may benefit from encouraging patients to share their experiences and consult a physician.