Binocular dysfunction in Parkinson's Disease: Decoding near triad dynamics and divergence deficits
Pooja Nambiar1, Aasef G Shaikh2, Palak Gupta3
1Case Western Reserve University School of Medicine, 9501 Euclid Ave, Cleveland, OH, 44106, USA; Visual Neurosciences and Ocular Motility Laboratory, Cole Eye Institute, Cleveland Clinic, 10605 Carnegie Ave, Cleveland, OH, 44106, USA.
Experimental Eye Research
|May 29, 2025
Summary
Parkinson's disease impairs eye movements, specifically reducing convergence and divergence responses in most patients. Accommodation and blur-driven vergence remain unaffected, offering insights into oculomotor dysfunction.
Area of Science:
- Ophthalmology
- Neuroscience
- Neurology
Background:
- Parkinson's disease (PD) is a neurodegenerative disorder affecting motor control.
- Oculomotor system dysfunction, including strabismus and vergence impairments, is common in PD.
- Convergence insufficiency is a notable issue for PD patients when viewing near objects.
Purpose of the Study:
- To evaluate eye deviation, vergence, accommodation, and pupil responses in PD patients during gaze shifts.
- To correlate oculomotor findings with neurologic severity using the Unified Parkinson's Disease Rating Scale (UPDRS).
- To investigate the impact of PD on disparity-driven and blur-driven vergence.
Main Methods:
- Recruited 19 participants with PD and 10 age-matched controls.
- Assessed eye deviation, vergence, accommodation, and pupil responses during converging and diverging gaze shifts.
- Correlated oculomotor function with UPDRS scores.
Main Results:
- 74% of PD participants showed reduced disparity-driven convergence and divergence responses.
- 37% of PD patients exhibited near exodeviation and reduced disparity-driven convergence.
- Blur-driven vergence was more reduced than disparity-driven vergence in both groups, likely due to presbyopia.
- Accommodation was comparable between PD patients and controls.
Conclusions:
- Parkinson's disease disrupts disparity-driven vergence, affecting convergence and divergence.
- Accommodation and blur-driven vergence are largely spared in PD.
- Findings suggest involvement of cerebellar and supra-oculomotor pathways in PD-related vergence deficits and strabismus.
- Oculomotor metrics may aid in evaluating therapies for binocular dysfunction in PD.
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