Characterization of the aqueous humor microbiome in Posner–Schlossman syndrome: an exploratory metagenomic sequencing study

Objective This study aims to characterize the aqueous humor (AH) microbiome in Posner–Schlossman syndrome (PSS) patients and evaluate its potential as a diagnostic and therapeutic target. Methods Metagenomic next-generation sequencing (mNGS) was performed on 59 AH samples from patients diagnosed with PSS ( n = 28) and myopia patients who underwent intraocular lens (ICL) implantation ( n = 31). Taxonomic profiling and diversity analyses were conducted to characterize the microbial communities. Interactions among microbial community members were evaluated using correlation analyses. Results Key findings revealed that intraocular microbiomes existed in both normal and diseased eyes; however, PSS patients exhibited lower microbial diversity (Shannon index, p = 0.066; Simpson index, p = 0.065) and distinct community structures (PERMANOVA, p = 0.05). Disease-specific microbial signatures were identified: Paeniglutamicibacter was uniquely enriched in the PSS group, whereas Escherichia coli dominated in the ICL group. Moreover, ecological network analysis demonstrated contrasting interaction patterns. The microbiomes in the PSS group formed stable, tightly connected networks with balanced positive/negative correlations, whereas those in the ICL group exhibited antagonistic relationships, suggesting competitive exclusion. These results challenge the traditional view of ocular sterility and reveal dynamic microbiome shifts associated with PSS pathogenesis. The enrichment of Paeniglutamicibacter in PSS may represent an associated microbial signature that could potentially reflect compensatory responses to chronic inflammation, although experimental validation is needed to confirm this hypothesis. Conclusion Our study provides preliminary evidence supporting the concept of intraocular microbiome dysbiosis in PSS, which requires validation in future studies. These findings suggest that potential microbial biomarkers warrant further investigation for their diagnostic and therapeutic implications.