Essential fatty acids in the treatment of dry eye

Essential fatty acids (EFAs) play many important roles in human biology, affecting organ systems and cellular and intracellular function. Omega-3 and omega-6 EFAs are the precursors of eicosanoids, locally acting hormones involved in mediating inflammatory processes. It is largely via the production of these eicosanoids that the essential fatty acids influence human health and disease. In general, the omega-3 derived eicosanoids are anti-inflammatory while the n-6 pathway eicosanoids promote inflammation. To date, EFAs have been primarily studied with regard to systemic diseases, particularly cardiovascular disease. Currently, no dietary recommendations of EFAs for the prevention or treatment of eye disease exist. The majority of studies concerning EFAs and eye disease have focused on diseases of the retina. This article provides an overview of the current literature regarding EFAs and dry eye disease (DED). Eight studies were identified, including six randomized controlled trials. All the studies preliminarily confirmed that there is a relationship between EFA supplementation and improvement in DED. However, strong conclusions cannot be made yet because of limitations in the research reported. The role of essential fatty acids is an important topic that would benefit from a large, multicenter, randomized clinical trial powered to reach a conclusion regarding the efficacy of essential fatty acids in the treatment of dry eye disease.