Glaucoma: Omega-3 supplements reduce intraocular pressure and therefore the risk of developing the disease

Only three months of treatment with omega-3 supplements is enough to reduce eye pressure by 8%, the main risk factor for glaucoma, a disease that affects the optic nerve causing irreversible damage to vision. The research, involving healthy young Australians, paves the way for new studies on the treatment and prevention of glaucoma, which represents one of the leading causes of blindness worldwide.

This is reported in an article published in the journal Translational Vision Science & Technology, presenting results obtained by two researchers from the University of Melbourne (Australia).

Omega-3: Allies of Eye Health 

Glaucoma is a disease affecting the optic nerve and represents the second leading cause of blindness worldwide after cataracts. Elevated intraocular pressure (IOP) is the main modifiable risk factor for glaucoma, making IOP reduction the primary goal in disease prevention. Eye pressure is determined by the amount of clear fluid, called aqueous humor, present in the eye, and its drainage.

The more fluid in the eyeball, the higher the pressure value, which should remain between 12 and 22 mmHg. It is interesting to note that intraocular pressure tends to increase with age in Western populations, while the opposite trend occurs in Japanese populations, who have a higher intake of polyunsaturated fatty acids through their diet.

Besides being involved in the prevention of cardiovascular diseases, hyperlipidemia, and inflammatory conditions, omega-3s seem to have positive effects on eye health. Diets rich in omega-3s are associated with a lower risk of various eye diseases, such as age-related macular degeneration. Previous studies have also reported that insufficient omega-3 intake may predispose to conditions like dry eye and glaucoma.

A large European study involving over 17,000 participants demonstrated an association between the ratio of omega-3 to omega-6 consumed and glaucoma, especially among older subjects. Another study, the National Health and Nutrition Examination Survey, enrolling 3,865 participants from the United States, reported that increased daily consumption of EPA and DHA is associated with a lower likelihood of glaucoma; the disease risk is nearly three times higher in those consuming low amounts of omega-3 compared to those with higher intake. Reducing intraocular pressure is therefore the cornerstone of glaucoma treatment, and current therapies rely on eye drops with this effect.

Identifying other risk factors, such as omega-3 deficiency, could expand intervention options for disease management.

EPA, ALA, and DHA reduce intraocular pressure after only three months of supplementation

Building on these premises, researchers at the University of Melbourne conducted a study to determine the effect of omega-3 supplements on IOP in young adults with normal blood pressure. Results revealed that after three months of treatment with EPA, ALA, and DHA, intraocular pressure had decreased by 8%, while it slightly increased in the group that did not take the supplements.

These results were consistent with previous animal studies. The effect of omega-3s is thought to result from several mechanisms that together may help reduce pressure: vascular regulation, neuroprotective properties, and anti-inflammatory effects. DHA, in particular, as widely demonstrated, has therapeutic potential for a broad range of neurodegenerative conditions, and increased omega-3 intake is beneficial for retinal function, the thin layer of cells in the eye that receives the image.

Other studies have shown that omega-3 supplementation has neuroprotective effects on the sensory peripheral nerves of the cornea in patients with dry eye disease. Additionally, omega-3 metabolism leads to increased production of substances called docosanoids, which help reduce IOP. Another relevant consideration concerns the contribution of vascular insufficiency to intraocular pressure, particularly reduced blood flow to the optic nerve, which plays a key role in glaucoma onset.

Omega-3s have been shown to reduce blood viscosity, which may beneficially affect optic nerve blood flow. A clinical study reported that people with a particular type of glaucoma (open-angle) had lower blood omega-3 levels compared to age-matched controls. Consistent with this finding, DHA levels in red blood cells of individuals with glaucoma decrease before clinical signs of glaucoma appear. Thus, sufficient dietary intake of EPA and DHA could allow effective modulation of ocular microcirculation and help prevent glaucoma development.

Some details of the research

To conduct the study, researchers analyzed data from 105 young adults, 73 women and 32 men, aged between 33 and 38 years, with no past or present glaucoma diagnosis and intraocular pressure below 21 mm Hg. Participants were randomly assigned to either a daily omega-3 treatment, composed of 1000 milligrams of EPA, 500 milligrams of DHA, and 900 milligrams of alpha-linolenic acid; or a placebo (1500 milligrams per day of olive oil). After three months of treatment, intraocular pressure was measured again, showing a relatively modest absolute reduction (~8%) in those who followed omega-3 supplementation, while IOP slightly increased in the control group.

The study paves the way for new investigations on the preventive role of omega-3

According to the study authors, this research is the first to demonstrate a reduction in intraocular pressure in humans after three months of supplementation with EPA and DHA in normotensive young adults. These results suggest further clinical investigation of the therapeutic potential of omega-3 supplements to reduce eye pressure and to prevent or treat pathological conditions such as ocular hypertension and glaucoma.

Source:

Laura Elizabeth Downie, Algis Jonas Vingrys. "Oral Omega-3 Supplementation Lowers Intraocular Pressure in Normotensive Adults". Translational Vision Science & Technology.