Key Points
Omega-3 EFA deprivation may predispose individuals to ocular disease in later life. Another significant eye disease that shows an age-dependent increase in prevalence is glaucoma, the second major cause of blindness worldwide. Currently, the major modifiable risk factor for glaucoma is elevated intraocular pressure (IOP). The effect of omega-3 supplementation on IOP in normotensive adults has not been investigated previously. This study analyzed pooled data from two double-masked, randomized, placebo-controlled trials (RCTs) to investigate whether a 3-month period of oral omega-3 supplementation significantly alters IOP in a population of normotensive adults consuming a typical Western diet. The data demonstrated that 3 months of systemic omega-3 supplementation significantly reduces IOP in young normotensive adults consuming a typical Western diet. The findings indicated a modest (8%) reduction in IOP; however, the Cohen’s effect size (d = 3.2) implied a substantial effect of major clinical significance. These data were consistent with previous experimental investigations, in animal models, showing that increasing dietary omega-3 fatty acid intake can lower IOP. Potential benefit(s) of omega-3 fatty acid dietary enhancement in modifying glaucoma risk may relate to neuroprotection and/or vascular regulation. Systemic anti-inflammatory modulation by omega 3 may contribute to the observed IOP-lowering effects, possibly through effects on outflow resistance through the trabecular meshwork and/or modulation of uveoscleral outflow. The findings justify further clinical investigation into the therapeutic potential of omega-3 fatty acid supplements for reducing IOP, to prevent and/or treat conditions that are associated with an elevation in IOP, such as glaucoma.
ABSTRACT
Purpose: Elevated intraocular pressure (IOP) is the major modifiable risk factor for the sight-threatening eye disease, glaucoma. We investigated whether oral omega-3 supplements affect IOP in normotensive adults. Methods: We undertook a pooled analysis of data from two double-masked, placebo-controlled randomized trials (Australian New Zealand Clinical Trials Registry, ACTRN12614001019695, ACTRN12615000173594) that investigated the efficacy and safety of oral omega-3 supplementation for treating ocular surface inflammation. Recruitment involved adults (n = 105) with IOP <21 mm Hg, and without a current or prior glaucoma diagnosis. Participants were randomly allocated to either an oral omega-3 (∼1000 mg/day eicosapentaenoic acid + ∼500 mg/day docosahexaenoic acid ± 900 mg/day α-linolenic acid) or placebo (olive oil, 1500 mg/day) supplement. IOP was quantified at baseline and after 3 months of supplementation (day 90). Change in IOP, relative to baseline, was compared between groups. Results: At baseline, participants were of similar age (omega-3/placebo groups: mean ± SEM, 33.7 ± 1.7, n = 72/35.6 ± 3.0 years, n = 33), sex (65%/79% female), and had similar IOP (14.3 ± 0.3/13.8 ± 0.5 mm Hg). At day 90, IOP was reduced to 13.6 ± 0.3 mm Hg in the omega-3 group; controls had a slight IOP increase to 14.2 ± 0.4 mm Hg (P < 0.05). Conclusions: Oral omega-3 supplementation for 3 months significantly reduced IOP in normotensive adults. To our knowledge, this is the first study to report that omega-3 fatty acids lower IOP in humans. Translational Relevance: These findings justify further investigation into the therapeutic potential of omega-3 supplementation for reducing IOP, to prevent and/or treat conditions with IOP elevation, including ocular hypertension and glaucoma.
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