Microbial diversity seen in closed eye microbiome of dry eye
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The closed eye microbiome of a dry eye has more microbial diversity compared with the closed eye microbiome of a control eye, which may result in dysregulation of closed eye neutrophils.
“Increased microbial diversity is something that is seen as largely favorable because it’s more resistant to perturbation. However, the increased diversity could actually be an indication of a decreased ability to regulate the microbiome, or it could also indicate an increase of pathobionts into the system,” Cameron K. Postnikoff, MASc, PhD, FAAO, said at the virtual Association for Research in Vision and Ophthalmology meeting.
Postnikoff and colleagues evaluated closed eye microbiomes in a therapeutic trial to test the effectiveness of an eye wash for dry eye disease. The clinical trial included 36 participants with normal eyes and 36 participants with dry eyes randomly assigned to perform eye washes, at awakening for either 1 month or once every 2 weeks, with phosphate buffered saline. Researchers took aliquots from tear washes at baseline and after 1 month. Metabarcoding was performed using the microbial 16S rRNA gene, Postnikoff said.
The closed eye microbiome of dry eye participants did not significantly change with daily eye wash. However, after analysis, the researchers noted the closed eye microbiome in dry eyes was distinct from control eyes. Five genera were identified that were distinct in the dry eye compared with the control subjects. The genera identified were OPB56, Bacteroidetes, Pseudomonas, Meiothermus and Methylobacteriaceae.
“The increased microbial diversity could result in dysregulation of the closed eye neutrophils, or it could be that the closed eye neutrophils are somehow dysregulated, leading to an increased microbial diversity in dry eye disease,” Postnikoff said.
The increased microbial diversity may also alter Th17 responses at the ocular surface and in dry eye disease, Postnikoff said.
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Postnikoff CK, et al. The closed eye harbors a distinct microbiome in dry eye disease: A randomized clinical trial of the efficacy of a saline rinse upon awakening. Presented at: Association for Research in Vision and Ophthalmology annual meeting; June 12, 2020 (virtual meeting).
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