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Omega-3s Lower Intraocular Pressure: Implications for Glaucoma

9/18/2018 1:58:21 PM
Glaucoma is a chronic condition that progressively damages the optic nerve, leading to vision loss and potential blindness. Because increased intraocular pressure (IOP) can contribute to optic nerve damage, a primary goal in glaucoma management is to lower IOP. IOP-lowering eyedrops are first-line therapy, and surgery is indicated in more advanced cases. Few other options exist to slow the progression of glaucoma.
Two recent randomized controlled trials, evaluating the effects of omega-3 supplementation on dry eye disease and contact lens discomfort, happened to evaluate IOP as part of their safety measures and secondary analyses. Those safety data caught the attention of the researchers, who subsequently published the pooled data specific to omega-3 supplementation and IOP. The article appeared in Translational Vision Science and Technology in 2018.
In total, the 2 studies included 105 adults with normal IOP (<21 mm Hg) and without a current or prior diagnosis of glaucoma. Participants consumed relatively low levels of dietary omega-3 fatty acids, consistent with a Western diet pattern. Participants were randomized to take omega-3 fatty acids from krill oil or fish oil or fish oil plus flax oil (~1000 mg/day eicosapentaenoic acid + ~500 mg/day docosahexaenoic acid) or placebo for 90 days. IOP was measured at baseline and the end of each 90-day trial. 
Participants in the omega-3 and placebo groups had similar mean IOP at baseline (14.3 mm Hg). After 90 days, mean IOP decreased by 8% in the omega-3 group (to 13.6 mm Hg) and increased slightly in the placebo group. The difference in the change of IOP between groups was significant (p <.05). 
These data are the first from clinical trials to suggest that omega-3 supplementation might lower IOP in humans. Although the magnitude of IOP change was small, it should be noted that the daily dosage of omega-3 fatty acids was moderate (~1500 mg/day), the duration of the study was short (90 days), and the study population had normal IOP at baseline. Omega-3 fatty acids have previously been shown to reduce the risk of glaucomatous optic neuropathy (by neuroprotective mechanisms) and may improve blood flow to the optic nerve (by reducing blood viscosity). Given that omega-3 fatty acids now also show promise in lowering IOP, further research should explore their potentially protective role in glaucoma.
Downie LE, Vingrys AJ. Oral Omega-3 Supplementation Lowers Intraocular Pressure in Normotensive Adults. Transl Vis Sci Technol. 2018; 7: 1.

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