A pilot study of assessing visual hallucinations using virtual reality in lewy body disorders.

Visual hallucinations (VH), defined a visual perception without a corresponding object in the visual environment, are characteristic of Lewy body disorders and associated with adverse outcomes. Clinical management remains limited by reliance on retrospective self-report and challenges distinguishing between various visual experiences. We piloted a structured virtual reality (VR) environmental exposure protocol to systematically characterize abnormal visual perceptual events. Participants were exposed to four environments under varying visual conditions and narrated their experience. Narratives were independently reviewed by two clinicians for abnormal visual perceptive events. Eleven participants with Parkinson's disease or dementia with Lewy bodies (6 VH+, 5 VH - by questionnaire) completed the protocol. Across participants, 23 abnormal perceptual events were identified (6 hallucinations, 17 misperceptions). Event phenomenology aligned with clinical descriptions and occurred more frequently during visually degraded conditions. Perceptual error events were observed more frequently in VR than typically captured through retrospective interview (2.09 vs. 0.016 per participant). However, event rates did not differ significantly between VH + and VH- groups and did not replicate participants' typical spontaneous hallucinations. Technical and methodological constraints further limit interpretation. These findings demonstrate the feasibility and tolerability of structured VR-based assessment of perceptual vulnerability in Lewy body disorders and support further development and validation of this approach.