PURPOSE. To determine whether there is an association between dietary omega-3 (-3) fatty acid intake, age, and intraocular pressure (IOP) caused by altered aqueous outflow.

METHODS. Sprague–Dawley rats were fed either -3–sufficient (-3+) or -3–deficient (-3–) diets from conception. The diets had 7% lipid content. The -3+ diet contained safflower, flaxseed, and tuna oils (5.5:1.0:0.5), and the -3– diet contained safflower oil only. Intraocular pressure was measured at 5 to 40 weeks of age under light anesthesia (-3+, n = 39; -3–, n = 48). Aqueous outflow was determined at 45 weeks in a subgroup of animals (-3+, n = 15; -3–, n = 22) using pulsed infusion. Ciliary body tissues (n = 6 per group) were assayed for fatty acid content by thin-layer and gas-liquid chromatography in both diet groups.

RESULTS. Animals raised on -3+ diets had a 13% decrease in IOP at 40 weeks of age (13.48 ± 0.32 mm Hg vs. 15.46 ± 0.29 mm Hg; P < 0.01). When considered as a change in IOP relative to 5 weeks of age, the -3+ group showed a 23% decrease (P < 0.001). This lower IOP in the -3+ diet group was associated with a significant increase (+56%; P < 0.001) in outflow facility and a decrease in ocular rigidity (–59%; P < 0.001). The -3+ group showed a 3.3 times increase in ciliary body docosahexaenoic acid (P < 0.001).

CONCLUSIONS. Increasing dietary -3 reduces IOP with age because of increased outflow facility, likely resulting from an increase in docosanoids. This indicates that dietary manipulation may provide a modifiable factor for IOP regulation. However, further studies are needed to consider whether this can modify the risk for glaucoma and can play a role in treatment of the disease.