Eye movement disorders: A new approach to preliminary screening of Parkinson's disease

To investigate the characteristics and diagnostic values of the eye movement disorders in patients with Parkinson's disease (PD-EMDs), this cross-sectional study enrolled 127 Chinese patients with PD and 80 healthy controls, and divided them into training and validation sets based on enrollment time. Performance in the five oculomotor paradigms was assessed using an infrared pupil and a corneal reflection tracking device. The primary characteristics of PD-EMDs were elucidated as inaccurate fixation with high deviation (frequency and total quantity); inaccurate saccades with delayed reaction and low velocity; saccadic pursuit with high deviation, delayed reaction, and velocity; and decreased visual search ability. Subgroup comparison shows that PD-EMDs can be related with PD stages, motor subtypes, frozen gait, and drowsiness. Finally, we developed and externally validated a model for PD preliminary screening using multivariate stepwise logistic regression analysis, comprising four oculomotor parameters (fixation accuracy, pro-saccade velocity, anti-saccade accuracy, and visual search duration), cognition score and educational years. The model has good feasibility with satisfactory performance on the receiver operating characteristic, calibration, and decision curves, and broad clinical applicability with better discrimination for more advanced PD patients and non-tremor-dominant PD patients. A nomogram was created to make the model more user-friendly in the clinical setting. Overall, we have demonstrated the presence of PD-EMDs and their prospective value for PD preliminary screening.