Strabismus, or misalignment of the eyes, is common in Parkinson’s disease (PD) and affects about one-third of patients. This condition arises from convergence insufficiency and PD-specific subcortical deficits, significantly impacting daily activities like reading and viewing near objects. Many patients experience double vision, with 55% showing significant eye misalignment during binocular viewing. This study aims to objectively assess binocular misalignment during near vision tasks, such as reading. We also examined the role of the subthalamic nucleus (STN) in strabismus during near fixation. Fixation stability and alignment were assessed in 33 PD patients and 10 healthy controls, revealing significant ocular misalignment, especially during monocular viewing. The application of bilateral STN deep brain stimulation (STN-DBS) improved eye alignment in most patients, underscoring the STN’s role in strabismus during near fixation in PD. This study highlights the need for further mechanistic research to develop effective interventions for visual deficits in PD.