ABSTRACT
Introduction
Microbiome research has grown exponentially, but the ocular surface microbiome (OSM) remains an area in need of further study. This review aims to explore its complexity, disease-related microbial changes, and immune interactions, and highlights the potential for its manipulation as a therapeutic for ocular surface diseases.
Areas Covered
We introduce the OSM by location and describe what constitutes a normal OSM. Second, we highlight aspects of the ocular immune system and discuss potential immune microbiome interactions in health and disease. Finally, we highlight how microbiome manipulation may have therapeutic potential for ocular surface diseases.
Expert Opinion
The ocular surface microbiome varies across its different regions, with core phyla identified, but with genus variability. A few studies have linked microbiome composition to diseases like dry eye, but more research is needed, including examining microbiome interactions with the host. Studies have noted that manipulating the microbiome may impact disease presentation. As such, microbiome manipulation via diet, oral, and topical pre- and probiotics, and hygienic measures may provide new therapeutic algorithms in ocular surface diseases.
Article highlights
The composition of the normal ocular surface microbiome (OSM) varies by ocular site, with a relatively pauci-bacterial cornea contrasted with a higher bacterial burden found within the conjunctiva and eyelid.
The composition of the OSM may change with disease, including with dry eye, among other conditions.
The natural immune system of the ocular surface relies heavily on a barrier function as well as intricate cell-mediated processes orchestrated by dendritic cells, macrophages and lymphocytes that interact with commensal bacteria.
Ocular commensal bacteria may stimulate the inflammasome to produce IL-1β, which can further exacerbate inflammation in autoinflammatory syndromes.
While techniques such as fecal microbiota transplant have yet to prove therapeutic in ocular surface disease, manipulation of the microbiome through diet, pro-biotics, topical therapy, and other medications may be a future therapeutic avenue.
Declaration of financial/other relationships
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
Reviewer disclosures
Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.