Findings from a recent study published in Translational Vision Science & Technology found that omega-3 fatty acid supplementation was linked to lower glaucoma risk in patients with dry eye disease (DED), spanning multiple glaucoma subtypes and the need for first-line glaucoma medications.
With 14,168 patients and a 5-year follow-up, this represents one of the larger longitudinal views on this question to date.
Give me some background first.
Some context: Omega-3s already hold the strongest supplement evidence in eye care for dry eye, with recommended daily doses running 420 to 3,000 mg.
But whether they do anything for glaucoma has stayed an open question.
Go on …
The plausibility is there. Patients with primary open-angle glaucoma (POAG) carry reduced blood levels of two major omega-3 fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).
In practice: Smaller clinical work has pointed the same way.
Case in point:
- A randomized controlled trial in 105 dry eye patients found oral omega-3 lowered intraocular pressure (IOP) more than placebo over 3 months
- And a separate analysis of POAG eyes reported improved visual field mean deviation with supplementation
But here's the issue: Those studies were short and small, and they tracked IOP rather than whether omega-3 lowers the odds of developing glaucoma.
And while a cross-sectional analysis of national U.S. nutrition survey data hinted at lower glaucoma risk with higher dietary omega-3 intake, cross-sectional data can't establish timing.
Which brings us to this new study.
Indeed. Researchers ran a multinational retrospective cohort study using deidentified records from the TriNetX Global Collaborative Network, pulling from more than 160 health care institutions across 21 countries between 2013 and 2023.
The design: Patients who received omega-3 prescriptions were matched 1:1 by propensity score against patients who never did, balancing age, sex, race, smoking, comorbidities, and corticosteroid use.
- A matched Cox proportional hazards model estimated risk, reported as hazard ratios (HRs) with 95% confidence intervals (CIs)
Worth noting: To limit reverse causation, outcomes were only counted starting 3 months after the index date, with follow-up running up to 5 years.
Who was included in the study?
Adults aged 18 or older with DED who had at least 1 year of follow-up. To flag continued use, the omega-3 group needed a second omega-3 prescription within a year of the first.
Investigators excluded anyone with a prior glaucoma diagnosis, previous glaucoma medications, laser trabeculoplasty, or autoimmune conditions that drive dry eye and often get treated with glaucoma-raising corticosteroids.
Demographics: After matching, 7,084 patients sat in each arm.
- Mean age was about 62.7 years, and mean follow-up ran 3.6 to 3.8 years across the two groups
- Baseline characteristics balanced cleanly, with all standardized mean differences under 0.1
And the findings?
Glaucoma, regardless of subtype, presented in 5.00% of the omega-3 group (354 patients) versus 10.43% of controls (739 patients), a hazard ratio (HR) of 0.48 (95% CI, 0.42 to 0.54).
The protective signal held across every subtype:
- Ocular hypertension: HR 0.57 (95% CI, 0.43 to 0.75)
- POAG: HR 0.45 (95% CI, 0.33 to 0.63)
- Normal-tension glaucoma (NTG): HR 0.41 (95% CI, 0.19 to 0.88)
- Primary angle-closure glaucoma (PACG): HR 0.45 (95% CI, 0.21 to 0.94)
As such: Omega-3 users were less likely to develop glaucoma and, subsequently, require first-line glaucoma medications (HR 0.65; 95% CI, 0.53 to 0.80). Kaplan-Meier curves separated for all outcomes, with log-rank P values below 0.05.
Tell me more.
The POAG benefit stayed consistent when investigators sliced the data by subgroup.
- In fact: It held for patients aged 60 or older (HR 0.51), females (HR 0.43), males (HR 0.47), and White patients (HR 0.27), as well as across hypertension, diabetes, and hyperlipidemia status.
Were there any exceptions to this?
No significant difference turned up among Asian participants. The authors tied this to a small sample and wide confidence intervals rather than a true absence of effect, and flagged racial differences as a question for future work.
Also worth noting: The NTG result.
- NTG develops without elevated IOP, leaning instead on vascular and neurodegenerative mechanisms, so a lower risk there points to omega-3 effects beyond pressure-lowering alone.
Any limitations to consider?
This was observational, so causation was off the table. The authors ran sensitivity analyses excluding glaucoma cases diagnosed within 1 to 12 months of omega-3 initiation—and the associations held— but residual confounding can't be ruled out.
Other gaps: TriNetX carries no dosage data, so there's no way to assess a dose-response relationship or pin down an optimal dose. The deidentified records also blocked independent verification of glaucoma diagnoses, which is partly why investigators tracked multiple subtypes plus medication initiation to tighten specificity.
That said: Patients on omega-3 may simply visit doctors more often, raising the odds glaucoma gets caught, while some controls may have taken over-the-counter omega-3 that went unrecorded.
- Both biases would shrink the gap, yet the lower risk persisted anyway.
Expert opinion?
The authors argued the consistency with prior trials and the biologic plausibility from animal work together suggest omega-3 could complement existing glaucoma prevention strategies.
They pointed to proposed mechanisms spanning lower IOP, better ocular blood flow, neuroprotection, and reduced oxidative stress and inflammation.
Anything else?
The supplement's reach goes past the eye.
The authors noted omega-3s also carry lipid-lowering, atherosclerosis-reducing, and heart-rhythm benefits, alongside potential value in dry eye, age-related macular degeneration (AMD), and cataract.
As such: They framed adequate omega-3 intake as a reasonable support for general health, while calling for randomized trials to confirm causality and work out dosing.