Comparative analysis of microbiota in the ocular surface of patients with atopic keratoconjunctivitis and Stevens-Johnson Syndrome with severe ocular complications.

Introduction: The interplay between host immunity and the microbiome is increasingly recognized as an important factor in ocular surface diseases. Although cutaneous and intestinal dysbiosis have been implicated in atopic dermatitis (AD), the role of the ocular microbiome in its severe ophthalmic manifestation, atopic keratoconjunctivitis (AKC), remains incompletely understood. Methods: We performed 16S rRNA gene sequencing to characterize the ocular and fecal microbiota of patients with AD and severe AKC, AD without severe ocular involvement, Stevens-Johnson syndrome (SJS) with severe ocular complications (SOC), and healthy controls. Microbial community composition was compared using principal coordinate analysis (PCoA) and taxonomic profiling. Results: Ocular microbiota composition differed among the study groups. PCoA demonstrated that SJS samples clustered separately from healthy controls, whereas AKC samples occupied an intermediate position between the healthy control and SJS groups. Taxonomic analysis revealed enrichment of Corynebacterium 1 (a SILVA genus-level taxonomic assignment) in SJS, while AKC samples exhibited increased relative abundances of both Corynebacterium 1 and Staphylococcus. In contrast, AD patients without severe ocular involvement maintained an ocular microbial community broadly similar to that of healthy controls, including the presence of Neisseria. Analysis of paired fecal samples did not reveal disease-associated clustering or major compositional differences among the study groups. Discussion: These findings suggest that, using genus-level 16S rRNA sequencing, disease-associated microbial alterations are more readily detected on the ocular surface than in the fecal microbiome in this cohort. The results support a potential contribution of the local ocular microenvironment to microbial signatures associated with immune-mediated ocular surface inflammation and provide a framework for future studies investigating the role of the ocular microbiome in disease pathogenesis.