Paired nasal mucosa and lacrimal sac microbiome features in recurrence after endoscopic dacryocystorhinostomy

PURPOSE: The nasal cavity and lacrimal sac are anatomically continuous; however, whether their resident microbiota influence surgical outcomes after endoscopic dacryocystorhinostomy (DCR) remains unclear. This study aimed to determine whether preoperative lacrimal sac microbiome features are associated with postoperative recurrence after endoscopic dacryocystorhinostomy. METHODS: In this prospective study, paired lacrimal sac and ipsilateral nasal mucosa samples were collected intraoperatively from 17 patients (22 operated sides) with acquired nasolacrimal duct obstruction. Bacterial communities were analyzed using 16S rRNA sequencing. Microbial diversity, composition, and nasal-lacrimal similarity were compared between relapse and non-relapse groups. RESULTS: Overall microbial richness, evenness, and community structure of the lacrimal sac did not differ between relapse and non-relapse groups (all p > 0.05). Both groups were predominantly composed of Proteobacteria with similar phylum-level distributions. Despite overall compositional stability, relapse samples showed enrichment of Staphylococcus lugdunensis, Pseudomonas balearica, and Corynebacterium, whereas non-relapse samples exhibited higher relative abundance of Mesorhizobium, Reyranella, and Ralstonia (p < 0.05). Functional prediction revealed increased representation of bacterial invasion and signaling-related pathways in relapse cases, while metabolic and regulatory pathways were more prominent in non-relapse cases. Nasal-lacrimal microbial similarity within individuals did not differ by outcome (all p > 0.05). CONCLUSION: The lacrimal sac microbiome remains compositionally stable in patients undergoing DCR; however, subtle differences in commensal composition and predicted microbial function are associated with postoperative outcomes. These findings suggest that the preoperative microbial environment may influence mucosal healing rather than reflect overt infection or disruption of the nasal-lacrimal continuum.