The connection between the gut and the eye continues to deepen, and a new Korean cohort study has added a compelling piece to the puzzle: patients who undergo gastrectomy appear to face a measurably higher long-term risk of developing dry eye disease (DED). Conducted using the Korean National Health Insurance Service–National Sample Cohort, the analysis examined more than 5,400 surgical patients and nearly 22,000 matched controls to determine whether major gastrointestinal (GI) surgery alters the trajectory of ocular surface health. The answer, at least for gastrectomy, is yes.
The idea that gut dysbiosis influences ocular surface inflammation is not new, but this is the first study to directly assess whether surgical alteration of the GI tract — a profound disruption to the microbiome, nutrient absorption, and immune signaling — is associated with later development of DED. Gastrectomy, in particular, is known to affect microbial diversity, gastric acid production, vitamin absorption, and mucosal immunity — all factors implicated in ocular surface integrity.
Among 2,346 gastrectomy patients and 9,384 matched controls, the authors found that gastrectomy was significantly associated with a higher risk of dry eye, with an adjusted hazard ratio (HR) of 1.09. Strikingly, total gastrectomy carried substantially greater risk, with an adjusted HR of 1.40 — a pattern consistent with the degree of physiological disruption caused by complete removal of the stomach.
The association was most evident in patients aged 60 years or older, males, urban residents, and those in lower-income groups — demographic nuances that may reflect disparities in postoperative nutrition, access to care, and systemic inflammatory burden.
In contrast, colectomy showed no increased risk. Among 3,086 colectomy patients and 12,344 controls, the adjusted HR was 1.00, with no significant findings across age, sex, or comorbidity subgroups. This divergence may underscore the anatomical specificity of the gut–eye axis: alterations to the upper GI tract — with its key roles in nutrient absorption and immune modulation — may exert more direct influence on ocular surface homeostasis than changes to the colon.
For ophthalmologists managing patients with complex systemic histories, the results carry several practical implications: post-gastrectomy patients may warrant closer monitoring for early signs of dry eye, especially after total gastrectomy; nutritional assessment — including vitamin A, omega-3 fatty acids, and zinc — may be relevant in patients with persistent ocular surface symptoms; the findings reinforce the bidirectional nature of ocular and systemic disease, highlighting the need for a collaborative approach between ophthalmology and gastrointestinal surgery.
While the study cannot prove causality, its large scale, long follow-up, and rigorous adjustment strategies provide some of the strongest epidemiologic evidence to date linking GI surgery and DED risk. As research continues to explore the gut–eye axis — from microbial metabolites to immune pathways — ophthalmologists may increasingly find that what happens in the gut does not stay in the gut.
