Causal Relationship Between Gut Microbiota and Cataract: A Two-Sample Bidirectional Mendelian Randomization Study.

Purpose: To identify the causal relationship between the gut microbiota and cataracts using a two-sample Mendelian randomization (MR) approach.

Methods: Genetic instrumental variables for gut microbiota were derived from a genome-wide association study (GWAS) of 18,340 participants. The aggregated statistics for cataracts, which involved 8,890 cases and 454,120 controls, were also obtained from GWAS. In addition, the inverse variance weighted method served as the primary analysis. Moreover, the weighted median method, MR-Egger regression, and MR Multieffect residual and outlier tests were performed to test the robustness of our results.

Results: Ultimately, we found a suggestive association between five bacterial traits and cataract risk: the ChristensenellaceaeR.7 group ( P =0.00175, odds ratio [OR]=0.995, 95% confidence interval [CI]: 0.991-0.998), Sellimonas ( P =0.0309, OR=0.998, 95% CI: 0.997-1.000), and Eubacterium ruminantium group ( P =0.0498, OR=0.998, 95% CI: 0.997-1.000) were negatively correlated with cataract, whereas Eggerthella ( P =0.0157, OR=1.002, 95% CI: 1.000-1.005) and Odoribacter ( P =0.0471, OR=1.004, 95% CI: 1.000-1.007) were positively associated with cataract. Heterogeneity was not observed in any of the five bacteria.

Conclusions: Our analysis provides evidence supporting a potential causal relationship between the gut microbiota and cataract risk. However, more research is needed to further elaborate on how gut microbiota affects cataract development.