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.