An examination of the relationship between low vision and Charles Bonnet syndrome

In recent years, the Low Vision Clinic (LVC) appeared to have a large percentage of patients admitting to phantom vision (Charles Bonnet syndrome [CBS]). The objective of this study was to learn more about CBS from an ophthalmological perspective, as research has been conducted primarily by other specialists.

Large-scale prospective study using a cohort of low-vision and normal-vision subjects.

Two hundred fifty-eight low-vision and 251 control subjects (with little or no vision loss) were enrolled.

A comparison of visual acuity, ophthalmic conditions, eye treatments, medications, mental state, general health, socialization, etc., was undertaken, and other factors influencing the hallucinations were recorded.

CBS was present in 34% of LVC subjects and in <2% of the general population with little or no vision loss. Many subjects had unformed hallucinations; bright lights or spot-like images should not be overlooked because they could be determined to be hallucinations upon further questioning of the patient. CBS occurred in subjects with visual acuity from 20/40 to 20/1600; subjects were twice as likely to have CBS if their visual acuity was between 20/301 and 20/800. The prevalence of CBS did not differ significantly by cause of visual problem. Thirty-four percent of people were distressed about their initial hallucination; many did not consult a doctor for an explanation, and if they did, many did not receive an adequate explanation.

This large-scale study shows that CBS is connected with a low vision level; thus, patients should be told about the common possibility of hallucinations.