Omega-3 Fatty Acid and Dry Eyes

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Dry eye is one of the most common problems faced by people living in urban settings. It is multi etiological, but the cause is frequently narrowed down to pollution and digital eyestrain.

Various over the counter eye drops and ointments are used to alleviate the symptoms of ocular discomfort and irritation, but the relief is usually temporary. But new researches have emerged that claims including Omega 3 fatty acids in the diet help effectively manage the dry eye condition.

 

What is Omega-3 fatty acid?

Omega-3 fatty acid (n-3 FA) is a type of polyunsaturated fatty acid (PUFA). There are several types of omega-3 fatty acid the most common examples are DHA, ALA, and EPA. The primary function of this fatty acid is to form and maintain the integrity of the cell membrane. Additionally, they also provide energy and have an integral function in well being of the heart, lungs, endocrine system, and immunity.

Dietary Recommendation

The dietary recommendation according to NIH is
  • Men = 1.6 gram
  • Women = 1.1g for women
  • The requirement is slightly higher for pregnant and lactating women. [1]
The deficit of omega 3 fatty acid can cause problems ranging from dry, scaly skin, dry eyes to risk of cardiovascular diseases, ARMD, and rheumatoid arthritis.

Sources of Omega-3

  • Fish and sea food are the most common and richest source of n-3 FA
  • Nuts and seeds: flaxseed, chia seeds, walnut, etc
  • Oils of canola, soyabean, sunflower
  • Other fortified items and pills
However, the plant-based sources provide ALA (Alpha Lineloic Acid), and only less than 15% of this gets converted into DHA and EPA in our bodies.

Omega−3 fatty acids and dry eyes

Omega−3 fatty acids has a very important role in the overall maintenance of ocular health. Few studies have proven its anti-inflammatory effects in both acute and chronic inflammation of ocular tissues.
A study by Miljanovic Et al with a sample size of 40 thousand women linked the decreased incidence of dry eyes to increased dietary intake of food rich in n-3 FA. [2] Similarly, Bhargava Et al conducted various studies in India on Rosacea patients, patients with computer vision syndrome contact lens wearers who experienced dry eye symptoms. Each study had around 500 participants and found improved symptoms and results with n-3 FA.[3,4,5]
However, a recent study conducted by DREAM (Dry Eye Assessment and Management) on 923 patients in the US found no improvement in the symptoms and signs of dry eyes in patients and concluded that the omega 3 fatty acid is nothing but a placebo. [6]
Many research projects are still being conducted on dry eyes and n-3 FA. A molecule called ‘resolvin’, derived from EPA and DHA appears to have a significant role in this process in mural cells. A study by Na li et al on the effect of resolving on mural cells concluded that Resolvin E1 (RVE1) promotes tear production.[7] RVE1 was also seen to inhibit corneal inflammation and protect goblet cells in mice.
Clinical trials for RVE1 are already taking place as prospective therapy options for dry eye management. Phase II study for RX-10045, an RVE1 prodrug, has already been completed by Celtic therapeutics. Further studies and trials show great potential for other resolvin types in the therapeutic management of dry eyes.

Other research

n-3 FA also appears to have a substantial role in visual transduction. A study by Litman Et al found that optimal DHA levels were vital in rhodopsin activation and the visual signaling process in the mural retina.[8]

 Furthermore, It also has good angiogenic effects, which can be beneficial for a wide range of ocular vascular diseases. Multiple researches have found that n-3 FA suppress the activities of various factors like VEGF (Vaso Endothelial growth factor), Platelet derived Vaso Endothelial Growth Factor (PdVEGF), Cyclo-oxygenase 2 (COX-2), and Prostaglandin-E2 (PgE2). [9]
There is few conclusive evidence in the benefit of n-3 FA in diseases such as ARMD, DR, RVO, RP and cataract.10However, the potential for the therapeutic use of n-3 FA for these conditions is being actively investigated.
 
Article By: Manashwi Karki, Optometrist, Nepal

References

1. National Institute of Health. Omega-3 Fatty Acids- Health Professional Fact Sheet.[internet]. USA. Updated Nov 30 2020. Available from [pubmed].

2) Miljanovic et al. Relation between dietary n−3 and n−6 fatty acids and clinically diagnosed dry eye syndrome in women.[internet].The American Journal of Clinical Nutrition. 2005 Oct 1[cited 2020 Dec 23]; 82(4): 887-893.[pubmed]

3. Bhargava R et al. Oral omega-3 fatty acids treatment in computer vision syndrome-related dry eye. Cont Lens Anterior Eye. 2015[cited 2020 Dec 23]; Vol 38:206–10. 

4. Bhargava R et al. A randomized controlled trial of omega 3 fatty acids in rosacea patients with dry eye symptoms. Curr Eye Res. 2016[cited 2020 Dec 23];41:1274–80. 

5. Bhargava R, Kumar P. Oral omega-3 fatty acid treatment for dry eye in contact lens wearers. Cornea. 2015[cited 2020 Dec 23];34:413–20. 

6. The Dry Eye Assessment and Management Study Research Group. Omega-3 fatty acid supplementation for treatment of dry eye disease.[internet] N Engl J Med. 2018[cited 2020 Dec 23]; 378(18): 1681–1690.[pubmed]

7. Na Li et al. Resolvin E1 improves tear production and decreases inflammation in a dry eye mouse model.[internet] J OculPharmacolTher. 2010 Oct[cited 2020 Dec 23];26(5):431-9.[pubmed]

8.Litman BJ et al. The role of docosahexaenoic acid containing phospholipids in modulating G protein-coupled signaling pathways: visual transduction. [internet]J MolNeurosci. Apr-Jun 2001;16(2-3):237-42. [pubmed]

9.  Spencer L et al. The effect of omega-3 FAs on tumour angiogenesis and their therapeutic potential. [internet]Eur J Cancer. 2009 Aug [cited 2020 Dec 23];45(12):2077-86.[pubmed]

9.  Hodge W et al.Effects of Omega-3 Fatty Acids on Eye Health: Summary[internet] AHRQ Ev Rep Summ. 2015 [cited 2020 Dec 23] [pubmed]

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