For a study, patients with Parkinson’s disease (PD) had abnormalities in saccade performance, pupil function, and blink rate. Isolated REM (rapid eye movement) Sleep Behavior Disorder (RBD) was a precursor to PD, making them ideal for research into early oculomotor abnormalities as PD biomarkers. Researchers in this study wanted to see if the saccade, pupillary, and blink responses in RBD were similar to those in PD. Patients with RBD (n=22), PD (n=22), and healthy controls (CTRL) (n=74) were investigated using video-based eye-tracking.

RBD patients had no statistically different saccadic behavior than CTRL patients, whereas PD patients varied from both CTRL and RBD patients. When compared to CTRL, both patient groups showed considerably reduced blink rates, attenuated pupil constriction, and dilation responses.

When compared to CTRL, RBD and PD patients displayed changed pupil and blink behavior. Due to the similarity of RBD and CTRL saccade features, pupil and blink brain regions may be altered before saccadic control areas, making them plausible prodromal PD markers.