A study published in the American Journal of Ophthalmology reveals a significant association between low vitamin D levels and an increased risk of developing dry eye disease (DED) among over 11 million adults. This longitudinal analysis indicates that individuals with vitamin D deficiency have a higher cumulative incidence of DED across various follow-up periods, suggesting a potential biological connection involving vitamin D signaling and eye health.
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DED is a common condition that can severely impact quality of life, with existing treatments often yielding inconsistent results and side effects. Researchers have explored vitamin D for its anti-inflammatory properties, with previous studies producing mixed conclusions. To clarify its role in DED, researchers analyzed data from the TriNetX US Collaborative Network, focusing on adults aged 18 and older.
The study involved two cohorts: 5.8 million patients diagnosed with vitamin D deficiency and 5.9 million controls without such a diagnosis, excluding those with a prior DED diagnosis. Findings showed that vitamin D deficiency was associated with a 28.6% increased hazard ratio (HR) for developing DED. Specifically, DED occurred in 3.3% of vitamin D-deficient individuals, compared to 2.7% of the controls. The cumulative DED incidence was notably higher in the vitamin D-deficient group over time; for example, after five years, the incidence was 3.58% versus 2.89% for controls, and after 20 years, it rose to 17.87% compared to 14.16%.
The authors noted the biological plausibility of a link between vitamin D deficiency and DED, stating that vitamin D is metabolized in the eye and that the vitamin D receptor (VDR) is present in ocular tissues. Experimental data indicate that active vitamin D can mitigate inflammation and oxidative stress in the corneal epithelium, supporting its potential protective role in eye health. The study also highlights the importance of maintaining a balanced micronutrient status for ocular health.
Limitations of the study include reliance on ICD-10 codes for defining deficiencies and dry eye, absence of serum vitamin D level data, and potential residual confounding factors. Additionally, social determinants of health were not captured in the database.
Given the significant association identified, the authors advocate for early screening and targeted intervention strategies to enhance ocular surface health, particularly for individuals at risk of vitamin D deficiency. They suggest that vitamin D supplementation may be a valuable adjunct to standard treatments for DED, though it should be guided by broader medical considerations. To solidify these findings, further prospective, randomized controlled studies are warranted to examine causality and assess whether vitamin D supplementation can effectively reduce DED incidence or severity.