The association between age-related macular degeneration and risk of Parkinson disease: A systematic review and meta-analysis.

Background: Numerous cohort studies have explored the association between age-related macular degeneration (AMD) and Parkinson disease (PD). However, a comprehensive meta-analysis on this topic is currently lacking. This study aims to address this gap by conducting a meta-analysis of existing cohort studies to investigate the relationship between AMD and the risk of developing PD.

Methods: Relevant studies were systematically identified through thorough searches of the PubMed, Web of Science, Embase, and Cochrane Library databases. Two investigators independently conducted data extraction. Cohort studies meeting the eligibility criteria and providing risk and precision estimates regarding AMD and the risk of PD were included. Pooled hazard ratio (HR) accompanied by 95% confidence interval (CI) were calculated using either a random-effects model or a fixed-effects model. Sensitivity analyses, involving the exclusion of 1 study at a time, were performed to assess the robustness of the findings. Publication bias was evaluated using Egger test.

Results: Five studies were included, encompassing a total of 4,771,416 individuals. Among these, 128,771 individuals had AMD, while 4,642,645 individuals did not. The pooled analysis revealed a significant increase in the risk of developing PD for individuals with age-related macular degeneration (hazard ratio [HR] = 1.44; 95% confidence interval [CI]: 1.22-1.71; I2 = 47.3%). Sensitivity analysis confirmed the robustness of the results. For the exploration of the relationship between nAMD and the risk of developing PD, 2 cohorts were included. The pooled analysis demonstrated a significantly elevated risk of PD for individuals with nAMD (HR = 2.21; 95% CI: 1.55-3.16; I2 = 0%).

Conclusion: This meta-analysis suggests a significant association between AMD and an increased risk of PD. These findings offer fresh perspectives on PD's etiology and pathogenesis, but should be interpreted with caution given the limitations in establishing causality.