Objective: To assess the associations of ocular physiology and visual function with the development of parkinsonism in a prospective population-based study.

Background: Several clinical studies and large-scale population-based health registries had reported an increase in association between poor vision/retinal thinning and parkinsonism diagnosis.

Method: We included those aged 45-85 years, living in one of 10 Canadian provinces between 2012-2015 at baseline. Parkinsonism was defined as a self-report of parkinsonism diagnosis, in combination with a confirmatory positive symptom screen and/or medication use. A panel of ocular physiological assessments, visual acuity tests and possible confounding comorbid health events were assessed cross-sectionally and longitudinally, in those with pre-existing or prodromal parkinsonism and controls. The direct associations/relative risks were assessed via regression with inverse probability weighting. Associations between parkinsonism signs/symptoms and visual impairment were assessed using the inverse probability weighted Kendall’s rank test.

Results: Overall, 112 participants had a diagnosis of parkinsonism at baseline and 58 developed parkinsonism at follow-up (mean interval ~3 years). No difference in ocular physiology was observed between those with prodromal/de-novo parkinsonism and those without. Participants with pre-existing parkinsonism had slightly lower ocular pressure than controls (OR=0.93[0.88,0.99]). Those with either prodromal or pre-existing parkinsonism demonstrated poor visual acuity (RR_prodromal=6.38[2.07,19.6], OR_pre-existing=5.18[2.40,11.2]) and increase in odds of visual impairment (RR=2.56[1.02,6.42], OR=3.37[1.78,6.40]) after correcting for refractory error. The association with visual impairment remained after accounting for induvial variance in both disease-groups. No clear increase in odds of visual impairment as the disease progress. Among those with pre-existing parkinsonism, visual impairment was associated with poor verbal fluency, delayed recall, prospective memory and balance (p<0.01). REM sleep behavior disorder and gait were not associated with visual impairment in parkinsonism.

Conclusion: Visual acuity impairment was associated with parkinsonism even at the prodromal phase. As the disease progress, visual impairment was associated with poor balance and non-vision dependent cognitive decline.

References: 1. Han G, Han J, Han K, Youn J, Chung Ty, Lim DH. Visual Acuity and Development of Parkinson’s Disease: A Nationwide Cohort Study. Mov Disord 2020. 2. Lin TP, Rigby H, Adler JS, et al. Abnormal visual contrast acuity in Parkinson’s disease. Journal of Parkinson’s Disease 2015;5(1):125-130. 3. Zhang J-r, Cao Y-l, Li K, et al. Correlations between retinal nerve fiber layer thickness and cognitive progression in Parkinson’s disease: A longitudinal study. Parkinsonism & Related Disorders 2021;82:92-97. 4. Murueta-Goyena A, Del Pino R, Galdós M, et al. Retinal Thickness Predicts the Risk of Cognitive Decline in Parkinson Disease. Annals of neurology 2021;89(1):165-176.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/visual-impairment-along-parkinsonism-development-and-the-association-to-non-vision-dependent-cognitive-decline-a-prospective-nation-wide-clsa-study/