Role of gut microbiomes in different ocular pathologies: A systematic review.

Background: The gut microbiome is integral to human health, with emerging research underscoring its potential impact on ocular health through the gut-eye axis. Various ocular disorders, such as dry eye syndrome, retinal vascular diseases, macular degeneration, and glaucoma, may be influenced by gut dysbiosis, which could significantly contribute to their development and progression.

Aim: To evaluate the influence of the gut microbiome on the pathogenesis and progression of various ocular diseases.

Methods: An extensive search of the scientific literature was undertaken by adhering to Preferred Reporting Items for Systematic Reviews & Meta-Analyses standards, using PubMed (MEDLINE), Scopus, EMBASE, and the Cochrane Library as sources to locate studies addressing the relationship between the gut microbiome and human health. To capture all relevant publications, search terms were systematically applied across these major databases, without limiting the search by language or publication date. Inclusion criteria covered randomized controlled trials, non-randomized controlled trial, prospective studies, cross-sectional studies, and case-control studies. Out of the 3077 articles, 36 full texts were included in the review.

Results: Ocular health appears to be shaped by the gut microbial community through mechanisms such as immune regulation, preservation of the blood-retinal barrier, and the generation of protective metabolites. Disturbances in this microbial balance can provoke measurable alterations in host immunity, providing a plausible immunopathogenic pathway that connects intestinal dysbiosis with eye disease. Both laboratory models and early human data suggest that targeted interventions, including prebiotics, probiotics, synbiotics, and faecal microbiota transfer, hold therapeutic potential.

Conclusion: The gut-eye relationship reflects a multifaceted interaction in which the intestinal microbiome contributes to ocular health through complex biological pathways. Integrating microbiome assessments into diagnostic methods can revolutionize disease management through early detection and targeted interventions. Further, randomised controlled clinical trials are necessary for ocular diseases to prove causal relationships.