Patients with dry eye disease (DED) suffer from chronic ocular discomfort. Even with current therapeutics and techniques in the management of DED, it is not unusual for these symptoms to be stubbornly persistent. There is a great amount of interest in the use of essential fatty acids (EFAs) as an adjunct in the treatment of DED. In other diseases, such as atherosclerotic heart disease, EFAs have been shown to play a role in inflammatory processes leading to observed pathologic changes. The cause of dry eye is often inflammatory in nature, so methods of modifying inflammation with EFAs may prove helpful to patients with DED.

Foods and supplements containing essential fatty acids (EFAs) are used to treat DED, some with more success than others. It is widely believed that omega-3 essential fatty acids, of which North Americans in particular are believed to have a very low normal dietary intake, may have benefits for maintaining normal tear production.¹ The two best sources of omega-3s are dark, oily, cold-water fish, and flaxseed. They are known to have a multitude of health benefits, yet, as a population, Americans are omega-3 deficient. In fact, Americans' dietary intake of omega-3s is among the lowest in the world.

Omega-6s are another group of essential fatty acids. Americans obtain an excess of omega-6s through their consumption of beef, dairy, vegetable shortening and cooking oils (i.e. hamburgers, cheeseburgers, pizza, ice cream, potato chips, etc.). It is thought that intake ratio of omega-3 to omega-6 EFAs ideally should be at least 1:4 and preferably 1:2.3.² However, the ratio is typically much lower (1:10–30) in a diet typical of developed countries which tends to be high in meat and processed food. In one study, a high intake ratio of omega-3 to omega-6 EFAs resulted in a decreased likelihood of suffering from dry eye syndrome (DES) in women, while women with lower than a 1:15 omega-3/omega-6 EFA ratio had a 2.5 times greater prevalence of DES.³ If too much omega-6 EFA is ingested due to a diet high in processed meats and low in unprocessed oils and omega-3 EFAs, then increased levels of pro-inflammatory prostaglandin E2 (PGE2), and low levels of anti-inflammatory agents PGE1 and PGE3, may lead to dry eye.⁴ The effectiveness of EFAs as a treatment for DES is dependent on the proper balance of omega-6 and omega-3 EFAs.⁵

The effectiveness of EFA treatment of DED is also dependent on specific nutrient cofactors that aid the metabolic conversion to anti-inflammatory prostaglandins.⁶ These nutrient cofactors stimulate the production of healthy goblet cells⁷ and enhance production of clearer and thinner meibomian gland secretion. Omega-3 EFAs also play an important role in the synthesis of meibum, the oil secreted by meibomian glands. People with omega-3 EFA deficiency typically have a thicker meibomian gland secretion.⁸ The use of omega-3 EFA supplements results in clearing and thinning of meibomian gland secretions which in turn improves symptoms of dry eye.⁸ Properly designed formulations also encourage lacrimal gland secretion⁹ and the production of tear lactoferrin.

To take advantage of the benefits of high omega-3 to omega-6 ratios, supplementation with oral compounds has become favorable. There are many options for EFA supplementation and, as these are unregulated by the United States Food and Drug Administration (FDA), it is very difficult to recommend a standardized formulation or dosage for patients. Typical omega-3 fish oil preparations contain 300mg of combined eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) per 1000mg capsule.¹⁰ Prescription omega-3 acids such as Lovaza, which are FDA-approved as treatment for hypertriglyceridemia, contain approximately 840mg EPA and DHA per 1000mg capsule. There are no formal recommendations or FDA-approved formulations for dietary consumption of EFAs in the treatment of eye disease, or the promotion of eye health.^11,12 From the cardiovascular point of view, the American Heart Association recommends two servings per week of fish high in omega-3 EFAs. It might be that these recommendations carry similar ocular benefits.

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