The closed eye harbours a unique microbiome in dry eye diseaseOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study asked whether the closed-eye tear microbiome differs in dry eye disease. Researchers collected tears on awakening from sleep during a randomized dry eye trial. They used 16S rRNA metabarcoding to characterize the bacterial community. Samples were taken at baseline and after one month. One trial arm used daily saline eye wash to test if the microbiome could be normalized.
Who was studied?
Participants were adults enrolled at the University of Alabama at Birmingham, USA. After stratification, 36 were classified as normal and 36 as dry eye, based on symptom scores and clinical tests. Arms were randomized to daily saline eye wash or no intervention. Baseline and one-month samples yielded 144 pooled two-eye tear collections. Dry eye subjects were older than controls, a noted limitation.
What were the most important findings?
The closed dry eye microbiome was distinct from the healthy closed eye. Dry eye communities were more diverse in richness, evenness, and Shannon diversity (all p below 0.001). PERMANOVA of Bray-Curtis dissimilarity confirmed distinct clustering. Dry eye differed in the relative abundance of 113 genera; at the phylum level Verrucomicrobia and Proteobacteria shifted most. Daily saline eye wash did not normalize the community. A support vector machine classified samples with 94 percent accuracy at baseline and 97 percent at one month.
What are the greatest implications of this study?
The findings implicate a distinct ocular surface microbiome in dry eye disease. Increased diversity may reflect breakdown of host control or incorporation of pathobionts. Because saline eye wash did not shift the community, moisture alone may not drive it. The study is observational and cannot prove the microbiome causes dry eye. The closed-eye microbiome could still inform future diagnostics and therapy targets.