Two-year longitudinal follow-up of visual illusions and hallucinations in Parkinson's disease

Background Previous longitudinal studies assessing visual hallucinations in Parkinson's disease (PD) have not specifically considered the respective evolution of visual illusions (VI) and visual hallucinations (VH), neither did they assess the role of ocular pathology on the evolution of those manifestations. Objective We aimed to determine whether VI evolve towards VH along the time in PD, and whether ophthalmological treatment may have a positive effect on the prognosis of those visuo-perceptive manifestations. Methods PD patients from a previous cohort [PD with VI (n = 26), PD with VH (n = 28), and PD without VI or VH (n = 28)] were contacted by phone 2 years later and questioned regarding the current presence of VI or VH, any current visual complaints, and the occurrence of any ophthalmological or antipsychotic treatment during the 2-year period, as well as any dopatherapy adjustment. Results Among PD-VI patients, 43% normalized, 48% remained PD-VI, 9% evolved towards coexisting VI and VH, and none converted to pure VH. Among PD-VH patients, 42% normalized, 32% remained PD-VH, 21% evolved towards coexisting VI and VH, and only 5% converted to pure VI. At follow-up, visual complaints remained greater among PD-VI and PD-VH compared to controls (p = 0.005). Among PD-VI and PD-VH who became control at follow-up, 35% received ophthalmologic treatment, 29% antipsychotic treatment, and 23% a dopatherapy reduction. Conclusion PD Patients with VI do not necessarily evolve towards VH over time, and ophthalmological treatment may have a positive effect on the prognosis of those visuo-perceptive manifestations in PD similar to antipsychotic treatment and dopatherapy adjustment.