Visual Acuity and Development of Parkinson's Disease: A Nationwide Cohort Study

Background: Visual dysfunction in Parkinson's disease (PD) is well known from previous reports, but the association of visual deficits with PD development has not yet been studied. The aim of this research was to evaluate the association of visual acuity with the risk of PD occurrence using a nationwide cohort in South Korea. Methods: Among the population participating in the National Health Insurance Service, which is mandatory for all South Koreans, 6,055,113 individuals who had taken part in health screening programs between January 1, 2009, and December 31, 2012, were included in the cohort and followed until December 31, 2017. The hazard ratio was calculated for groups with high and low visual acuity using multivariate adjusted Cox regression analysis. Results: A total of 22,872 subjects (0.38%) were diagnosed as having PD within the study period. Groups with low visual acuity showed a higher incidence of PD compared with groups with good visual acuity. Compared with the reference group (visual acuity better than 20/20), the adjusted hazard ratios and 95% confidence intervals (CIs) was 1.315 (95% CI, 1.261–1.371) for the group with visual acuity between 20/20 and 20/60, 1.357 (95% CI, 1.277–1.442) for the group with visual acuity between 20/60 and 10/100, and 1.267 (95% CI, 1.193–1.343) for the group with visual acuity less than 10/100. Conclusions: Low visual acuity was associated with the development of PD. This suggests that visual dysfunction is one of the premotor symptoms for PD development.