Exploring the Ocular Microbiome: A New Frontier in Ophthalmology

Excerpt
“The eye, once thought sterile and immunoprivileged, is entangled in systemic crosstalk between microbial tenants and ocular health.”

In its September 2025 issue, The Ophthalmologist published a feature article co-authored by Prof. Farhad Hafezi and Dr. Mark Hillen that challenges long-held assumptions about sterility and immunity in the eye. It presents a bold thesis: that ophthalmology’s next revolution may come not from engineered molecules, but from microbes living within and around us.

The article introduces the gut–eye axis, showing how the ocular microbiome influences conditions as diverse as dry eye disease, glaucoma, uveitis, AMD, and diabetic retinopathy. The familiar narrative of the eye as an isolated, sterile organ is dismantled, replaced by an image of constant microbial dialogue between the gut, ocular surface, and intraocular compartments.

One striking example is the concept of the lacriome, the microbial community of the tear drainage system. Once regarded as simple plumbing, the nasolacrimal system emerges as a micro-ecosystem where shifts in microbial balance may determine whether surgery succeeds or fails. Similarly, in meibomian gland dysfunction, the usual explanation of gland obstruction is reframed: bacteria on the lid margin may be shaping gland health and ocular surface stability.

The article also questions the assumption of sterility in the anterior chamber. Evidence of microbial DNA in aqueous humor samples suggests that resident organisms could influence immune tone and even contribute to glaucoma pathophysiology. Equally provocative is the evidence linking gut bacteria to autoimmune uveitis, in which microbes may “train” T cells to attack retinal antigens.

Across these examples runs a common theme: dysbiosis—microbial imbalance—can tip the balance from health to disease. This perspective does not dismiss established mechanisms like intraocular pressure in glaucoma or complement dysregulation in AMD, but it adds another layer: the possibility that microbial communities, shaped by diet, environment, and medication, act as hidden co-authors of disease.

Therapeutically, the horizon is equally challenging. Microbiome modulation through probiotics, prebiotics, or even fecal transplants has shown promise in experimental models. But the risks—unintended inflammation, infections, or unpredictable immune responses—are real. The article cautions against premature translation, stressing the need for rigorous, multi-omics trials before clinical adoption.

For ophthalmology, this shift is profound. Health can no longer be equated with sterility, nor disease with contamination. Instead, the focus may turn toward symbiosis, acknowledging that the eye is part of a much broader microbial ecology.