**Retinal Imaging in Neurodegenerative Disease Study** This study is exploring how changes in the eyes might relate to brain diseases like Alzheimer's and Parkinson’s. It uses special cameras and scans: *OCT* (Optical Coherence Tomography) and *OCTA* (OCT Angiography) to take pictures of the tiny blood vessels and structures in the eyes. These tools help researchers find early signs of disease by looking at the eyes' blood flow and structure. The study hopes to show that these eye scans can be a useful tool in detecting brain diseases early. **Key Points:** - **Participation Duration:** You will need to visit the study site for eye scans. - **Eligibility:** Adults with or without brain diseases can join, but you shouldn't have had eye surgeries except for cataracts. - **Benefits:** Help improve early detection of brain diseases, though there may be no direct benefit to you. *This study is a chance to contribute to important research that could help with early diagnosis of brain diseases.*