Characterization of the Microbial Profile in Tears of Patients with Primary Open-Angle Glaucoma: Results from a Pilot Study

Abstract This pilot study aimed to characterize the tear microbiota in patients with primary open-angle glaucoma (POAG) and compare to healthy controls. Tear samples from 22 participants (10 with POAG, 12 controls), matched by age and sex, were analyzed using 16S rRNA sequencing to assess microbial diversity and taxonomic composition. While alpha diversity showed no significant differences, beta diversity analyses revealed distinct microbial community structures between groups. Patients with POAG exhibited a more uniform microbiota and fewer bacterial genera overall. Notably, three phyla—Fusobacteriota, Planctomycetota, and Synergistota—were significantly more abundant in the glaucoma group (p < 0.0001). At the genus level, 23 genera displayed significant differences in relative abundance: 10 genera were significantly less abundance, and 13 genera were significantly more abundant in POAG compared to controls. These findings support the hypothesis of ocular dysbiosis associated with POAG and highlight specific microbial shifts potentially linked to inflammatory or immune mechanisms involved in disease progression. The study suggests that microbiota-based therapies such as probiotics or postbiotics might represent novel adjunctive strategies for managing glaucoma and calls for larger, longitudinal studies to validate these preliminary results and explore clinical applications.