Improving eye vergence function in persons with Parkinson’s disease

Improving eye vergence function in persons with Parkinson’s disease

Eye-tracking tools can support clinicians in the management of Parkinson’s Disease (PD) patients. Over 30 years of research has shown that PD profoundly impacts the control of eye movements. These include: pupil reactivity, smooth pursuit, saccadic movements, optokinetic response, and vergence [1-3]. Recently, research examining the ability to improve vergence eye impairments and related symptoms.

Convergence is the ability of the eyes to rotate towards each other to focus on a nearby object. The prevalence of impaired convergence, known as convergence insufficiency, is estimated at 40% in PD patients [4]. Convergence insufficiency impacts quality of life directly by impacting activities of daily living such as reading or working on a computer and can result in the presence of symptoms including blurred vision, headaches, diplopia. A recent study by Machan, C.M. et al (2020), showed that vergence training significantly improved convergence in PD study participants after only two months of training [5]. Although considered preliminary due to the small sample size, this initial evidence highlights there may be potential benefits of including vergence interventions aimed at helping patients with PD.

Vergence eye movements, convergence and divergence, can be captured and measured using video-oculography (VOG) techniques [6-8] and can support clinicians in the management of patients with Parkinson’s Disease.

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References:

1 Armstrong, R.A., Visual Dysfunction in Parkinson’s Disease. Int Rev Neurobiol, 2017. 134: p. 921-946.

2 Crotty, G.F. and B.K. Chwalisz, Ocular motor manifestations of movement disorders. Curr Opin Ophthalmol, 2019. 30(6): p. 443-448.

3 Jung, I. and J.S. Kim, Abnormal Eye Movements in Parkinsonism and Movement Disorders. J Mov Disord, 2019. 12(1): p. 1-13.

4 Irving, E.L., et al., Prevalence of Convergence Insufficiency in Parkinson’s Disease. Mov Disord Clin Pract, 2017. 4(3): p. 424-429.

5 Machan, C.M., et al., Changing vergence function in persons with Parkinson’s disease and convergence insufficiency. Parkinsonism Relat Disord, 2020. 73: p. 41-43.

6 Slovak, M., et al., Antisaccades and vergence abnormalities in functional movement disorders: A video-oculographic study. Mov Disord, 2016. 31(7): p. 1072-3.

7 Hanuska, J., et al., Fast vergence eye movements are disrupted in Parkinson’s disease: A video-oculography study. Parkinsonism Relat Disord, 2015. 21(7): p. 797-9.

8 Balaban, C.D., et al., Patterns of Pupillary Activity During Binocular Disparity Resolution. Front Neurol, 2018. 9: p. 990.