Uncovering the relationship between the human ocular surface microbiome and gut microbiome

The human body harbors diverse microbial communities that play essential roles in health and disease. While the gut microbiome (GM) has been extensively studied and linked to numerous systemic conditions, the ocular surface microbiome (OSM) remains less well understood due to its low microbial biomass and technical challenges in sequencing. Previous work has suggested possible connections between gut dysbiosis and ocular disease, but whether the OSM and GM are directly related remains unclear. This study investigated the relationship between the ocular surface microbiome (OSM) and the gut microbiome (GM) by analysing matched samples from both niches in the same individuals. Using high-throughput sequencing, we characterised microbial composition and diversity at each niche, followed by statistical analysis to show common taxa. A Mantel test was applied to assess potential correlations between the two microbial communities. Our results revealed no significant correlation between the composition of the OSM and GM, neither in structure nor in diversity. This study suggests that the two niches are shaped independently, likely due to their distinct environmental conditions and microbial densities. These findings highlight the uniqueness of each microbiome and underscore the need for niche specific approaches when investigating host microbiome interactions. ClinicalTrials.gov, TRN: NCT02438111, Registration date: 28 April 2015, and TRN: NCT 04658238, Registration date: 01 December 2020.