The results of a 535-participant strong trial showed that there was no significant difference in the extent of symptom improvement between the Dry Eye patients who were taking daily omega-3 supplements and those who were taking placebo Olive Oil capsules. The trial aimed to study the effects of supplementation on patients with moderate to severe dry eye. Of the 535 participants, 349 were randomly assigned omega-3 while the remaining 186 got olive oil. Neither the participants nor the researchers in the study knew their group assignment. The research was conducted by the independently-led Dry Eye Assessment and Management (DREAM) Research Group and funded by the National Institutes for Health's (NIH) National Eye Institute (NEI).

Why were omega-3 supplements studied?

Omega-3 supplements have been thought to curb the inflammation caused by dry eye (also known as dry eye syndrome). Even though there has never been strong evidence to support this idea, both patients and clinicians have supported their use as an addition to standard treatments. Dry eye is usually treated using artificial tears or anti-inflammation eye drops. Without treatment, dry eye can cause the eye's front surface to become scarred and can also lead to having light-sensitive eyes as well as blurry vision.

What happened in the trial?

The omega-3 group was given three grams of fish-derived omega-3 fatty acids through five daily supplements. The placebo group was given five grams of olive oil instead in the form of identical-looking capsules.

Patients were allowed to continue using their normal dry eye treatments in the trial to mimic real-life conditions where supplements are only used as add-on treatments.

What were the trial results?

Blood tests from both groups after 12 months showed that the mean EPA levels for the omega-3 group, a component of omega-3, had quadrupled, while levels remained the same for the placebo group.

But for both groups, the mean levels of oleic acid, a component of olive oil, remained the same. There was also no significant difference found in the extent of symptom improvement between both trial groups at the end of the trial, despite both groups reporting a significant improvement in symptoms.

Symptom improvement was measured by looking at the difference between the scores of patient-reported symptoms on the Ocular Surface Disease Index (OSDI) at the beginning and the end of the trial.

The OSDI uses a 100-point scale to measure the severity of patient symptoms and higher values indicate worse symptoms. A reduction of at least 10 points on the OSDI is considered to be significant enough for a patient to notice an improvement in symptoms. 61 percent of the omega-3 group reported a significant improvement in symptoms, whereas the figure for the placebo group was 54 percent. The omega-3 and placebo groups reported mean reductions of 13.9 and 12.5 points respectively. Standardized clinical tests were also unable to show significant differences between the groups when it came to the improvement of signs of the condition.