Observational study of deep brain stimulation and eye focusing problems in Parkinson's disease

Inability to align and refocus the eyes on the objects at different depths, i.e., vergence impairment and strabismus, frequently affects the quality of life in patients with Parkinson's disease. The investigators study aims to understand the location-specific effects of subthalamic region deep brain stimulation on vergence and strabismus by integrating the patient-specific deep brain stimulation models and high-resolution eye-tracking measures. The knowledge gained will allow the investigators to find the most beneficial stimulation location and parameters for improving binocular coordination, strabismus, and vergence while preserving the ability to treat motor symptoms in Parkinson's disease.