Dysbiosis of Ocular Surface Microbiota in Patients With Refractive Allergic Conjunctival Diseases

We investigated ocular surface microbiota dysbiosis in patients with refractory allergic conjunctival diseases (ACDs; stratified into mild and severe groups) treated with topical tacrolimus.

Patients (n = 21) with refractory ACDs (including vernal and atopic keratoconjunctivitis) actively treated with topical tacrolimus and 6 healthy controls were evaluated. Based on clinical scores and expression of specific cytokines on the ocular surface, patients with ACDs were divided into mild and severe groups using cluster analysis. The microbial composition of tear specimens collected from patients with mild and severe ACD and control subjects using the Schirmer test paper was determined through next-generation 16S rRNA sequencing analysis.

Compared with healthy controls, patients with ACDs exhibited significantly decreased ocular surface microbiota α-diversity. Ocular surface microbiota mainly comprised members of the phyla Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria in all groups. The relative abundance of ocular surface microbiota in patients with ACDs was increased for phylum Firmicutes and decreased for phylum Proteobacteria (compared with control subjects). The genera Blautia (vs. mild ACD group) and Morganella (vs. control group) exhibited significantly increased abundance only in the severe ACD group.

The ocular surface microbiota in patients with severe ACD exhibited decreased diversity and exacerbation of dysbiosis compared with that in patients with mild ACD and control subjects. Patients with mild refractory ACD also exhibited decreased diversity of these microbiota. These alterations in microbiota indicated a change in the ocular surface of patients with refractory ACD (be it because of disease pathogenesis or topical immunomodulatory treatment).