Screening for Charles Bonnet syndrome: Should the definition be reconsidered?

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.

Prevalence of Charles Bonnet syndrome in patients with glaucoma: a systematic review with meta-analyses

Glaucoma is a widespread sight-threatening condition often only recognized when very pronounced. It is initially characterized by peripheral visual field losses, while advanced stages also affect the central vision. Some of these patients may experience visual hallucinations, the Charles Bonnet syndrome (CBS). In this systematic review and meta-analysis, we provide an overview of the literature dealing with the prevalence of CBS in patients with glaucoma. We searched the databases PubMed/MEDLINE, Embase, Web of Science, the Cochrane Central and PsycInfo on 22 March 2020. Eight studies (n = 827 patients) were identified and included for a qualitative and quantitative analysis. No studies included a representative sample of patients with only glaucoma. In patients with glaucoma in different stages and with ocular comorbidities, prevalence of CBS was 2.8% (CI95%: 0.7-6.1%). Among patients with glaucoma where all had bilateral low visual acuity, prevalence of CBS was 13.5% (CI95%: 8.4-19.6%). In patients with glaucoma who visited vision rehabilitation clinics, presumably due to an extensive vision impairment, prevalence of CBS was 20.1% (CI95%: 16.8-23.6%). Risk factors of CBS besides low vision were high age, female gender, reduced contrast sensitivity and not living alone. Taken together, we find that CBS may not be rare in patients with advanced glaucoma with and without ocular comorbidities. However, limitations of the current literature should be highlighted and careful approach towards conclusions is important. More studies are needed to better understand the prevalence and risk factors among different populations of patients with glaucoma.

Prevalence of visual hallucinations

BACKGROUND

To determine the prevalence of visual hallucinations and to report its associations with demographic and clinical factors in a population-based survey in India.

METHODS

Prevalence of visual hallucinations was determined as a part of a large prospective, cross-sectional, population-based study that was carried out in two districts of Telangana, namely Khammam and Warangal. Multi-stage cluster random sampling was used in this study. The administration of the questionnaire preceded the clinical examination of the subjects. Associations with factors such as age, sex, education level and visual impairment categories were studied using univariate analysis and multiple logistic regression.

RESULTS

Out of the 6,000 subjects who were enumerated from the 120 clusters in Khammam and Warangal districts, a total of 4,936 (82.3 per cent) responded. The mean age of the participants was 55.6 ± 11.8 years. Only the older age group (> 70 years of age) was associated with visual hallucinations on univariate analysis (p < 0.001). On multiple logistic regression, subjects with moderate visual impairment were found to have higher odds of experiencing visual hallucinations (odds ratio 1.48; 95% confidence interval 1.12-1.96, p = 0.006) and those who were older also had higher odds (odds ratio 1.35, p = 0.06).

CONCLUSION

The prevalence of visual hallucinations among those with visual impairment in this population-based study was 13.8 per cent. The older age group and moderate visual impairment were noted to be the associated factors among individuals experiencing visual hallucinations.