This observational clinical trial investigates how deep brain stimulation (DBS) of the subthalamic nucleus (STN) affects visuomotor function in patients with Parkinson's disease. Specifically, the study focuses on vergence — the coordinated movement of both eyes to maintain binocular alignment when focusing on objects at different distances. Vergence deficits are a common but understudied non-motor symptom in PD that affects reading, depth perception, and daily activities.
The study aims to characterize how STN DBS influences vergence metrics and identify optimal stimulation locations and parameters that can preserve motor symptom control while improving binocular coordination.
| Parameter | Value |
|---|---|
| NCT Number | NCT05400499 |
| Status | Recruiting |
| Phase | Not Applicable (Observational) |
| Sponsor | VA Office of Research and Development |
| Study Type | Observational (Cohort) |
| Enrollment | 40 participants (estimated) |
| Start Date | October 4, 2022 |
| Primary Completion | June 30, 2026 |
| Completion Date | July 1, 2026 |
| Location | Louis Stokes VA Medical Center, Cleveland, OH |
Parkinson's disease affects not only motor function but also oculomotor control. Patients with PD commonly experience:
These deficits impact:
The subthalamic nucleus (STN) is a key component of the basal ganglia-thalamocortical circuit and a primary target for DBS in Parkinson's disease. While STN DBS is highly effective for motor symptoms (rigidity, bradykinesia, tremor), its effects on oculomotor function are less understood.
The STN has connections to:
This study investigates how modulating STN activity through DBS affects these interconnected systems involved in vergence control.
A key innovation of this study is integrating patient-specific DBS models with high-resolution eye-tracking:
This approach allows researchers to correlate specific stimulation locations with vergence outcomes, potentially enabling optimized targeting for both motor and oculomotor symptoms.
The study enrolls veterans with Parkinson's disease who have undergone bilateral STN DBS implantation:
The primary outcome measure is dynamic eye alignment measured using non-invasive high-resolution video oculography:
| Metric | Description |
|---|---|
| Vergence ratio | Ratio of actual versus desired vergence movements |
| Vergence latency | Delay from target change to vergence onset |
| Peak vergence velocity | Maximum speed of vergence eye movements |
| Binocular congruency | Agreement between left and right eye positions |
Participants perform vergence tasks while their eye movements are recorded:
Non-motor symptoms are increasingly recognized as major contributors to disability in Parkinson's disease:
This study addresses a critical gap — understanding how DBS affects these understudied symptoms.
By correlating stimulation location with vergence outcomes, this research may enable:
As a VA-funded study, this research directly addresses the health needs of veterans with Parkinson's disease, a population with significant service-related exposures and age-related neurodegenerative disease risk.
| Role | Name | Contact |
|---|---|---|
| Principal Investigator | Aasef G. Shaikh, MD PhD | (216) 791-3800 ext 60000 |
| Study Coordinator | Monica O'Loughlin | (216) 791-3800 |
| Study Coordinator | Cheryl Dudek | 216-679-3800 |
Institution: Louis Stokes VA Medical Center, Cleveland, OH 44106-1702