Glaucoma: omega-3 supplements reduce intraocular pressure and thus the risk of developing the disease

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

This is reported in an article published in the journal Translational Vision Science & Technology, outlining the findings of two researchers from the University of Melbourne, Australia.

Omega-3 allies of ocular health 

Glaucoma is a disease that affects the optic nerve and is 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 of disease prevention. Ocular pressure is determined by the amount of clear fluid, called aqueous humor, found in the eye and its drainage. 

The more fluid in the eyeball, the higher the pressure value, which should remain in the range of 12 to 22 mmHg. Interestingly, intraocular pressure tends to increase with age in Western populations, but the opposite trend occurs in Japanese populations, who have a higher dietary intake of polyunsaturated fatty acids. 

In addition to being implicated in the prevention of cardiovascular disease, hyperlipidemia and inflammatory conditions, omega-3s appear to have positive effects on eye health. In fact, omega-3-rich diets are associated with a lower risk of several eye diseases, such as age-related macular degeneration. Previous studies have also reported that insufficient omega-3 consumption may predispose to conditions such as dry eye and glaucoma.

A large study conducted in Europe, involving more than 17,000 participants, showed an association between the ratio of omega-3 and omega-6 consumed in food and glaucoma, especially among older individuals. Another study, the National Health and Nutrition Examination Survey, which enrolled 3865 participants from the United States, reported that increased daily consumption of EPA and DHA, is associated with a lower likelihood of glaucoma; and the risk of the disease is almost three times greater in subjects consuming low amounts of omega-3, compared to those consuming more. Reducing intraocular pressure is therefore the cornerstone goal of glaucoma treatment, and currently, therapies are based on the use of eye drops with this effect. 

Identifying other risk factors, such as precisely omega-3 deficiency, could increase intervention options for managing the disease.

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

Based on these assumptions, 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. The results revealed that after three months of treatment with EPA, ALA and DHA, IOP had decreased by 8 percent, while it had increased slightly in the group of subjects who had not taken the supplements. 

Such findings were consistent with those of previous animal studies. The effect of omega-3s would be due to several mechanisms that together may contribute to pressure reduction: vascular regulation, neuroprotective properties, and anti-inflammatory properties DHA, in fact, as has been widely shown, has therapeutic potential for a wide range of neurodegenerative conditions, and increased dietary omega-3 consumption is beneficial for the function of the retina, the thin film of the eye composed of image-receiving cells. 

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

Omega-3 has been shown to reduce blood viscosity, and this may produce beneficial effects on optic nerve blood flow. One clinical study reported that people with a particular type of glaucoma (open-angle), had lower blood omega-3 levels than age-matched controls. Consistent with this finding, it has been reported that DHA levels in the red blood cells of individuals with glaucoma, are reduced before the onset of clinical signs of glaucoma. Thus, sufficient dietary intake of EPA and DHA could allow effective modulation of ocular microcirculation, and help prevent the development of glaucoma.

Some details of the research

To conduct the study, researchers analyzed data from 105 young adults, 73 women and 32 men, aged 33 to 38 years, with no past or present diagnosis of glaucoma and an intraocular pressure of less than 21 mm Hg. Participants were randomly assigned either a daily omega-3 treatment, consisting of 1000 milligrams of EPA, 500 milligrams of DHA, and 900 milligrams of α-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 reduction in absolute terms (~8 percent) in those who had followed omega-3 supplementation, while IOP was slightly increased in the control group. 

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

According to the study authors, the research is currently 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 into 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.