TABLE 2.
Ambient light level and visual hallucination (VH) in Charles Bonnet syndrome (regardless of the primary ophthalmologic illness)
| Study [ref.], year, country | Participants | Study design and measurements | Cognitive and other psychiatric remarks | Main findings on light conditions |
|---|---|---|---|---|
| Teunisse et al., 10 1994, The Netherlands | N = 14 (F = 13), age 73–95 years old (mean = 81.8) | Cross section case series. Self‐reported questionnaires followed by MMSE and psychiatry interview | MMSE scores: 10–28 or 25–30 after correction for visual impairment. One with concurrent organic amnestic syndrome and one with dementia. Two with major depressive disorder and two with dysthymic disorder | Facilitated circumstances a : Profound darkness: 2 (14%) Poor lighting: 7 (50%) Bright daylight: 1 (7%) |
| Khan et al., 11 2008, UK | N = 97 (F = 59), mean age 80.3 years old (SD = 6.0) | Cross section cases (n = 97) with non‐VH controls (n = 263). Patients were assessed by an ophthalmologist and a visual symptoms questionnaire | Not formally assessed. Education level and percentage of cases and controls with depression and other psychiatric conditions were similar | Precipitating circumstances: Night or low light: 31 (32.0%) Mornings or on waking: 4 (4.1%) None (at any time): 52 (53.6%) Other: 10 (10.3%) |
| Vukicevic et al., 12 2008, Australia | N = 33 (F = 25), age 65–92 years old (mean = 77.7) | Cross section cases (n = 33) with non‐VH controls (n = 30). Referred by ophthalmology clinics for general health, demographic and VH/CBS experience interview | Not formally assessed. 16/33 reported moderate or severe stress as a result of VH. Education level was similar between cases and controls (primary: Secondary education = 79:21 and 80:20) | Light intensity during VH: Darkness: 1 (3%) Dim light: 6 (18.2) Bright light: 20 (60.6%) Unsure: 6 (18.2%) |
| O’Hare el al., 13 2015, Australia | N = 27 (out of 72 advanced retinitis pigmentosa patients) | Part of a larger natural history study of retinitis pigmentosa. Full ophthalmological examination and a CBS questionnaire | No formally assessed. No education or psychiatric conditions/history reported in the study published | Light intensity during VH: Darkness: 3 (11.0%) Dim light: 3 (11.0%) Bright light 6 (22.2%) Both light and dark: 3 (11.0%) Not light dependent 12 (44.7%) |
Abbreviations: CBS, Charles Bonnet syndrome; VH, Visual hallucinations.
a
Percentage not rounded to 100 as some facilitated circumstances were not relevant to light conditions.