Visual Hallucinations in Eye Disease and Lewy Body Disease

Objectives Visual hallucinations (VH) most commonly occur in eye disease (ED), Parkinson disease (PD), and Lewy body dementia (LBD). The phenomenology of VH is likely to carry important information about the brain areas within the visual system generating them. Methods Data from five controlled cross-sectional VH studies (164 controls, 135 ED, 156 PD, 79 [PDD 48 + DLB 31] LBD) were combined and analyzed. The prevalence, phenomenology, frequency, duration, and contents of VH were compared across diseases and sex. Results Simple VH were most common in ED patients (ED 65% versus LBD 22% versus PD 9%, χ 2  = 31.43, df = 2, p   0.001), whereas complex VH were more common in LBD (LBD 76% versus ED 38%, versus PD 28%, χ 2  = 96.80, df = 2, p   0.001). The phenomenology of complex VH was different across diseases and sex. ED patients reported more "flowers" (ED 21% versus LBD 6% versus PD 0%, χ 2  = 10.04, df = 2, p = 0.005) and "body parts" (ED 40% versus LBD 17% versus PD 13%, χ 2  = 11.14, df = 2, p = 0.004); in contrast, LBD patients reported "people" (LBD 85% versus ED 67% versus PD 63%, χ 2  = 6.20, df = 2, p = 0.045) and "animals/insects" (LBD 50% versus PD 42% versus ED 21%, χ 2  = 9.76, df = 2, p = 0.008). Men reported more "machines" (13% versus 2%, χ 2  = 6.94, df = 1, p = 0.008), whereas women reported more "family members/children" (48% versus 29%, χ 2  = 5.10, df = 1, p = 0.024). Conclusions The phenomenology of VH is likely related to disease-specific dysfunctions within the visual system and to past, personal experiences.