Omega-3 and omega-6 polyunsaturated fatty acids for dry eye disease.

Systematic review and meta-analysis of adults with dry eye disease from diverse causes and settings, including Sjögren's syndrome, meibomian gland dysfunction, post-LASIK or post-cataract surgery, computer vision syndrome, contact lens-related dry eye, rosacea, and other ocular or systemic comorbidities. Trials were conducted across multiple countries and compared oral omega-3 and/or omega-6 supplements with placebo, omega-6, combination formulations, or conventional therapy.

Oral long-chain omega-3 polyunsaturated fatty acid supplements, and in some comparisons omega-6 preparations or omega-3 plus conventional therapy, were evaluated for dry eye disease. Across trials, formulations, doses, and treatment durations varied substantially, and comparators included placebo, omega-6, combination regimens, or conventional therapy.

Overall, the evidence was mixed and generally of low to moderate certainty. For long-chain omega-3 versus placebo, there was no consistent improvement in subjective dry eye symptoms, although some trials showed modest benefits in objective signs such as tear production, tear osmolarity, and TBUT, with substantial heterogeneity. Adding omega-3 to conventional therapy may improve symptoms versus conventional therapy alone, but the certainty was low. When omega-3 was compared with omega-6, some analyses favored omega-3 for symptom improvement. The authors concluded that heterogeneity in formulations, doses, durations, populations, and risk of bias limits confidence in the findings.

Substantial heterogeneity in supplement formulations, doses, durations, and patient populations limited pooling and interpretation. The certainty of evidence was low to moderate, and risk of bias was a concern, including industry funding in several trials. Reporting was inconsistent across studies, with incomplete and uneven outcome data for many comparisons.