Investigating the Ocular Surface Microbiome: What Can It Tell Us?

Abstract

While pathogens of the eye have been studied for a very long time, the existence of resident microbes on the surface of healthy eyes has gained interest only recently. It appears that commensal microbes are a normal feature of the healthy eye, whose role and properties are currently the subject of extensive research. This review provides an overview of studies that have used 16s rRNA gene sequencing and whole metagenome shotgun sequencing to characterize microbial communities associated with the healthy ocular surface from kingdom to genus level. Bacteria are the primary colonizers of the healthy ocular surface, with three predominant phyla: Proteobacteria, Actinobacteria, and Firmicutes, regardless of the host, environment, and method used. Refining the microbial classification to the genus level reveals a highly variable distribution from one individual and study to another. Factors accounting for this variability are intriguing - it is currently unknown to what extent this is attributable to the individuals and their environment and how much is artifactual. Clearly, it is technically challenging to accurately describe the microorganisms of the ocular surface because their abundance is relatively low, thus, permitting substantial contaminations. More research is needed, including better experimental standards to prevent biases, and the exploration of the ocular surface microbiome’s role in a spectrum of healthy to pathological states. Outcomes from such research include the opportunity for therapeutic interventions targeting the microbiome.

Keywords:

• ocular surface
• ocular surface microbiome
• 16s rRNA gene sequencing
• whole metagenome shotgun sequencing

Abbreviations

OSM, ocular surface microbiome; OS, ocular surface, CALT, conjunctiva-associated lymphoid tissue; WA, weighted average; WM, weighted median; HPV, Human papilloma virus; MCV, Merkel cell polyomavirus; BRiSK, Biome representational in silico karyotyping; TTV, Torque teno virus; ITS, internal transcribed spacer; MA, mean abundance; GO, Gene Ontology.

Disclosure

VGP reports a grant from Peter Mayor Gedächtnis-Stiftung. MSZ reports grants from Foundation Bertarelli Catalyst Fund, EPFL (Ecole Polytechnique Fédérale de Lausanne) and Lausanne, Switzerland (CF10000044 – EPFL SCR0237812), during the conduct of the study. He also reports grants, personal fees from Bayer, personal fees from Novartis, non-financial support from Heidelberg Engineering, outside the submitted work. Dr Denise C Zysset-Burri reports grants from OPOS foundation, St. Gallen, Switzerland and Foundation Bertarelli Catalyst Fund, EPFL (Ecole Polytechnique Fédérale de Lausanne), Lausanne, Switzerland (CF10000044 – EPFL SCR0237812), during the conduct of the study. The authors report no other conflicts of interest in this work.