Dry eye disease affects an estimated 344 million people globally, yet clinical management has long focused narrowly on topical treatments while overlooking systemic contributors. A growing body of evidence now points to diet and gut microbial health as meaningful upstream modulators of ocular surface inflammation — a shift that repositions dry eye as a systemic condition with dietary leverage points.
This review synthesizes current evidence on how polyunsaturated fatty acids, particularly omega-3s (EPA and DHA) and omega-6s, modulate the inflammatory cascades underlying dry eye disease by influencing eicosanoid and resolvin production — lipid mediators that regulate ocular surface immune tone. Antioxidant-rich dietary patterns, notably the Mediterranean diet, were associated with improved tear film stability and reduced oxidative stress markers at the ocular surface. Conversely, common food additives were flagged as potential disruptors of both systemic and ocular surface health. The review places particular emphasis on the gut-eye axis: gut dysbiosis — driven by poor diet, aging, or antibiotic overuse — was linked to amplified systemic inflammation, impaired immune regulation, and reduced short-chain fatty acid (SCFA) production, molecules that help maintain mucosal and immune homeostasis. The ocular microbiome itself was identified as an active participant in corneal immunity. Emerging therapeutic strategies including probiotics, prebiotics, and fecal microbiota transplantation (FMT) are discussed, though current evidence remains largely preclinical.
While the conceptual framework here is compelling, the practical clinical translation remains premature. Most supporting studies are small, observational, or animal-based, and no standardized probiotic strain or dietary protocol has demonstrated replicated efficacy in well-powered dry eye trials. The gut-eye axis hypothesis, though biologically plausible given parallels with gut-skin and gut-lung axes, still requires prospective mechanistic studies in human cohorts. This review is best read as a well-organized synthesis of an emerging paradigm rather than actionable clinical guidance — incremental but directionally important for both ophthalmology and nutritional medicine.
