Recurrent visual hallucinations in patients with vision loss who have normal mental status and insight into the unreal nature of the perception have been called Charles Bonnet Syndrome after the naturalist who in 1769 described the hallucinations that his clear-thinking and visually impaired grandfather experienced.1 This peculiar symptom of vision loss is often under-reported by patients for fear of negative consequence and is often under-diagnosed by clinicians.

As part of a larger prospective study of vision rehabilitation in patients and morbidity, 225 consecutive patients seen over a 1-year period were asked the following question: ‘Many patients who come to this Clinic see things that they know are not there. Some see colored shapes or organized patterns or they may even see vivid images of people, animals or flowers. Have you ever experienced this?’ Patients were seen again 1 year later and asked the same question.

The mean age of patients seen was 80 and 141 (63%) had age-related macular degeneration. More than one-third had ⩾6/18 visual acuity in their better-seeing eye. As previously reported, a total of 78 patients (35%) reported seeing visual hallucinations at the initial visit.2 After 1 year, 152 patients were seen again, 19 were deceased, and 54 were not seen owing to illness, moving out of the community, or because they were not interested to return. Of the 54 patients seen at 1 year who had initially reported hallucinations, 15 patients (28%) no longer experienced the hallucinations. Of the 98 patients seen at 1 year who had not initially reported hallucinations, 23 (24%) now reported that they had started experiencing this symptom. The appearance or disappearance of the hallucinations could not be correlated to any change in visual parameters such as visual acuity or contrast sensitivity.

Visual hallucinations are a common symptom among patients with vision loss, and unless asked about this symptom most patients will not inform their clinician, despite the fact that they are concerned about why they are experiencing this peculiar symptom. Patients are very reassured when the nature of the hallucinations is explained to them. The results of this study allow clinicians to counsel patients that 28% of patients cease to experience these hallucinations after 1 year.