OBJECTIVE To study complex visual hallucinations in visually impaired individuals. METHODS A prospective comparative study involving structured history taking and cognitive assessment in 48 consecutive visually impaired individuals with best-corrected visual acuity of 20/200 or worse and an age-matched cohort of 48 consecutive patients with visual acuity of 20/40 or better in at least 1 eye. ...

The pathophysiology of visual hallucinations in Parkinson's disease has yet to be characterized. Although stimulus-driven ("bottom-up") processes are known to be impaired, the role of "top-down" processes remains to be determined. Distinguishing between conscious and non-conscious detections (i.e. access to consciousness) may be a valuable way of monitoring top-down processes. Conscious access ...

Visual hallucinations occur when our conscious experience does not accurately reflect external reality. However, these dissociations also regularly occur when we imagine the world around us in the absence of visual stimulation. We used two novel behavioural paradigms to objectively measure visual hallucinations and voluntary mental imagery in 19 individuals with Parkinson's disease (ten with vi...

Visual hallucinations are relatively uncommon presentations in medical and psychiatric clinics, where they are generally regarded as a marker of possible underlying "organic" brain disease. Thus, patients with visual hallucinations are often referred for imaging of the brain. This article presents a pragmatic approach for the radiologist reviewing such imaging. Because conditions that can prese...

BACKGROUND Charles Bonnet syndrome is characterized by complex, formed visual hallucinations that occur in patients without psychiatric disorders. To the best of our knowledge, it has not been described following central retinal artery occlusion. OBJECTIVE To describe 2 patients who experienced formed visual hallucinations characteristic of Charles Bonnet syndrome after sudden, severe visual ...

BACKGROUND Patients with Parkinson's disease (PD) experience visual hallucinations, which may be related to decreased contrast sensitivity (ie, the ability to discern shades of grey). OBJECTIVE The objective of this study was to investigate if an online research platform can be used to survey patients with Parkinson's disease regarding visual hallucinations, and also be used to assess visual ...

Hallucinations are a psychopathological phenomenon with neuropsychological, neuroanatomical and pathophysiological correlates in specific brain areas. They can affect any of the senses, but auditory and visual hallucinations predominate. Verbal hallucinations reveal no gross organic lesions while visual hallucinations are connected to defined brain lesions. Functional neuroimaging shows impairm...

Between 8 and 40% of Parkinson disease (PD) patients will have visual hallucinations (VHs) during the course of their illness. Although cognitive impairment has been identified as a risk factor for hallucinations, more specific neuropsychological deficits underlying such phenomena have not been established. Research in psychopathology has converged to suggest that hallucinations are associated ...