Dietary omega 3 fatty acids decrease intraocular pressure with age by increasing aqueous outflow

PURPOSE. To determine whether there is an association between dietary omega-3 (ω-3) fatty acid intake, age, and intraocular pressure (IOP) caused by altered aqueous outflow. METHODS. Sprague-Dawley rats were fed either ω-3-sufficient (ω-3⁺) or ω-3-deficient (ω-3^-) diets from conception. The diets had 7% lipid content. The ω-3⁺ diet contained safflower, flaxseed, and tuna oils (5.5:1.0:0.5), and the ω-3^- diet contained safflower oil only. Intraocular pressure was measured at 5 to 40 weeks of age under light anesthesia (ω-3⁺, n = 39; ω-3^-, n = 48). Aqueous outflow was determined at 45 weeks in a subgroup of animals (ω-3⁺, n = 15; ω-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 ω-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 ω-3⁺ group showed a 23% decrease (P < 0.001). This lower IOP in the ω-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 ω-3⁺ group showed a 3.3 times increase in ciliary body docosahexaenoic acid (P < 0.001). CONCLUSIONS. Increasing dietary ω-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.