Objective To elucidate the potential mechanisms by which Chinese herbal medicine (CHM) regulates gut microbiota (GM) to influence the development of primary open-angle glaucoma (POAG).

Methods Data mining, network pharmacology, and Mendelian randomization (MR) analyses (two-sample design) were conducted in integration to systematically explore the CHM-GM-POAG axis. Literature-based data mining method was applied to identify frequently used herbs and herb pairs for POAG, and the properties and meridian tropism of the herbs were analyzed as well. Target prediction and pathway enrichment analyses were performed to identify shared molecular pathways among CHM components, GM, and POAG. MR analysis was performed to assess the genetically predicted causal associations between specific microbial taxa and POAG risk.

Results Our data mining work indicated that commonly used CHMs were mainly bitter and sweet in flavors and cold in property, with meridian tropism toward the liver, lung, and kidney. The predominant therapeutic effects of the CHMs included soothing the liver and regulating Qi, promoting blood circulation, and reducing fluid retention. Representative herb pairs were Shudihuang (Rehmanniae Radix Praeparata)-Gouqi (Lycii Fructus) with Zexie (Alismatis Rhizoma), Gouqi (Lycii Fructus)-Fuling (Poria) with Shudihuang (Rehmanniae Radix), and Juhua (Chrysanthemi Flos)-Gouqi (Lycii Fructus) with Zexie (Alismatis Rhizoma). Network pharmacology revealed overlapping targets involving antioxidative, anti-inflammatory, and metabolic regulation pathways. MR analysis demonstrated that higher abundances of Ruminiclostridium 6 odds ratio (OR) = 0.73, 95% confidence interval (CI): 0.58 – 0.92, P = 0.007, Ruminococcaceae UCG-002 (OR = 0.77, 95% CI: 0.63 – 0.96, P = 0.018), Ruminococcus torques group (OR = 0.71, 95% CI: 0.57 – 0.90, P = 0.004), and Victivallis (OR = 0.82, 95% CI: 0.70 – 0.96, P = 0.016) were causally associated with reduced POAG risk, whereas Actinomyces (OR = 1.34, 95% CI: 1.06 – 1.68, P = 0.013) and Blautia (OR = 1.39, 95% CI: 1.01 – 1.90, P = 0.042) showed positive associations.

Conclusion This study revealed potential causal links between GM and POAG and provided integrative evidence that CHM may modulate the microbiota to exert neuroprotective effects. These findings offer new integrative insights into the gut-eye axis and a theoretical basis for developing microbiota-targeted CHM strategies in glaucoma management.