<;figure>;<;img width=";128"; height=";52"; src=";https://www.sciencealert.com/images/2023/08/ParkinsonsEyeScans.jpg"; class=";attachment-thumbnail size-thumbnail"; alt=";"; decoding=";async"; srcset=";https://www.sciencealert.com/images/2023/08/ParkinsonsEyeScans.jpg 1024w‚ https://www.sciencealert.com/images/2023/08/ParkinsonsEyeScans-642x260.jpg 642w‚ https://www.sciencealert.com/images/2023/08/ParkinsonsEyeScans-768x311.jpg 768w‚ https://www.sciencealert.com/images/2023/08/ParkinsonsEyeScans-600x243.jpg 600w"; sizes=";(-webkit-min-device-pixel-ratio: 2) 50vw‚ (min-resolution: 192dpi) 50vw‚ (min-resolution: 2dppx) 50vw‚ (-webkit-min-device-pixel-ratio: 3) 33.33vw‚ (min-resolution: 288dpi) 33.33vw‚ (min-resolution: 3dppx) 33.33vw";>;<;/figure>;<;p>;Open your eyes.<;/p>;