Ocular conjunctival microbiome profiling in dry eye disease: A case control pilot study.

Purpose:Keratoconjunctivitis sicca (KCS) or dry eye disease (DED) is a multifactorial disease that results in discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. A pilot study was undertaken to determine if there were any major substantial differences in the ocular microbiome in DED patients versus healthy controls. Methods:The bacterial communities residing in the conjunctiva of patients with DED (n = 4) and healthy controls (n = 4) were assessed by 16S ribosomal RNA (rRNA) gene sequencing of the V4-V5 region. Results:The phyla Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes were most dominant and accounted for 97% and 94.5% of all bacterial sequences in patients and controls, respectively. At the genus level, 27 bacterial genera were found with more than two-fold difference between patients and controls. Four of these - Acinetobacter, Corynebacterium, Lactobacillus, and Pseudomonas spp. - dominated the ocular microbiome of all subjects, but were proportionately lower in DED (16.5%) compared to controls (37.7%). Several bacterial genera were found to be unique in DED (34) and controls (24). Conclusion:This pilot study is an attempt to profile the ocular microbiome in patients with DED that demonstrated a higher concentration of microbial DNA compared to controls, with Firmicutes phyla dominating the bacterial population in patients with DED.