The objective of this study is to determine whether visual pathway structure and function correlates with hallucination severity and treatment outcomes in Parkinson disease. The primary outcome variable is hallucination severity, which will be quantified using the PD-adapted Scale for the Assessment of Positive Symptoms (SAPS-PD), a standardized semi-structured instrument that rates nine symptoms of psychosis on a 0-5 scale (total score ranges from 0-45). The SAPS-PD has been extensively validated (inter-rater reliability 0.84, intra-class coefficient 0.94) and is the standard outcome measure for clinical trials of hallucination treatments in PD, including the pivotal phase III trial of pimavanserin that led to its FDA approval in this population. There are two secondary outcome variables: 1) low-contrast letter acuity score, and 2) retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thickness measured using optical coherence tomography (OCT).

You may be eligible for this study if you meet the following criteria:

• Conditions: Medical Research
• Age: - 99 Years
• Gender: All