Dr Carlos Vergés, Dra Irene Sassot.
Area Oftalmológica Avanzada.
In previous articles we have pointed out the importance of nutrition and chronic stress as the main cause of many diseases. Oxidative stress occurs with increased levels of free radicals, which would be the pathogenic origin of various general and ocular diseases 1, such as cataracts, macular degeneration associated with age, glaucoma and dry eye syndrome.
Oxidative stress is a high intracellular concentration of reactive oxygen species (ROS), such as oxygen ions (O2-), hydrogen peroxide (H2 O2), among others. These elements are also known as free radicals and its concentration increases due to endogenous and exogenous antioxidants can not remove them properly. The consequences of oxidative stress is the appearance of widespread inflammation that affects all body tissues and especially the eyes. (If you want to know more about stress, click).
In dry eye, the focus is inflammation that affects the lacrimal glands, meibomian glands of the eyelid (figure 1) and eye surface. This inflammation is responsible for a decrease in tear production and changes in lipid composition (fat-secreting meibomian glands), (figure 2), which lubricate the eyeball and form the outer layer of the tear film, which prevents evaporation and thus the eye surface from drying out. These changes are responsible for the microtrauma when blink, because the continuous friction on the cornea, increase tear osmolarity, instability of the tear film (figure 3), and surface inflammation, effects that are added causing tissue damage in a continuous and progressive manner. It’s a vicious circle centered on inflammation.
Figure 1. Meibography of the upper eyelid showing areas without Meibomian glands (blue arrows).
Figure 2. Interferometry analysis of the external lipid layer. Iridescent areas of lipids (blue stars).
Figure 3.- Noninvasive break up time videokeratography (NIBUT) of the tear film, showing break areas (arrow) and the rupture time graph (star).
There is increasing evidence pointing out the importance of nutritional factors in the inflammatory basis of dry eye. Perhaps the most significant study is the Women’s Health Study 2, where 39,876 women are analyzed and the relationship between diet and the presence of dry eye is found. When the diet was rich in Omega 3 and low in omega-6 fatty acids, the incidence of dry eye was low, whereas when descending omega 3 and increased omega 6, the incidence of dry eye shot.
Other studies also show that a diet rich in omega 3 and low in omega-6, is associated with a beneficial effect on patients with dry eye and has even been seen to prevent their occurrence in the population at risk, as in postmenopausal women, older 65 years 3. On the same line of investigation, was evident that the composition of the lipids of the meibomian glands and tears was anomalous in diets low in omega-3 and omega-6 excess. Lipid composition in meibomian glands was normalized when food intake was corrected, boosting omega 3 and reducing omega 6 4,5.
The beneficial effect of omega-3 in dry eye is due to its anti-inflammatory effects 6-10, both in primary and secondary forms (when associated with other diseases such as Sjögren, rheumatic or autoimmune processes). The inflammation of the ocular surface is responsible to the tissue injury and for the subjective complaints that patients notice.
A breakthrough in this field is the fact of having a test, very simple to implement, which detects inflammation (metalloproteinase 9) and directs us for diagnosis and treatment. One problem that arises is that we can not use anti-inflammatory drugs for a long time, so it is as effective rebalance the diet, the anti-inflammatory effect enhancing omega-3, reducing omega-6 and increasing the intake of antioxidants.
A very important factor and little-known when it comes to diets high in omega 3, is the fact that the food we eat and especially supplements rich in omega 3, are degrade just to enter the body, undergo a process of oxidation and lose its beneficial effect. To avoid this circumstance, it is essential to raise the level of antioxidants, both endogenous and exogenous. There is already evidence that points out the combination of omega 3 supplements and antioxidants, such as vit C and E and polyphenols, present in black chocolate and red wine, with high antioxidant activity and the capacity to potentiate the action of omega-3.
For the treatment of dry eye, through diet and stress control, to be effective, it is important to know the oxidation state of each patient, the level of free radicals, and the curve of DHEA and cortisol and also, levels omega 3 and omega 6 in erythrocytes. Currently we can detect these biomarkers and adjust suitable therapeutic measures in each case. We have seen that it is not enough general recommendations. The data we get from these analyzes allow us to tailor treatment and, importantly, allows us to better assess the effectiveness of the measures we have taken.
1.- Richer SP, Rose RC. Water soluble antioxidants in mammalian aqueous humor: interaction with UV B and hydrogen peroxide. Visión Res 1998;38:2881-8.
2.- Miljanovic B, Trivedi KA, Dana MR, et al. Relation between dietary n-3 and n-6 fatty acid and clinically diagnosed dry eye syndrome in woman. Am J Clin Nutr 2005:82:887-93.
3.- Oxholm P, Asmussen K, Wiik A, et al. Essential fatty acid status in cell membranes and plasma of patients with primary Sjogren´s syndrome. Correlation to clinical and immunologic variables using a new model for classification and assessment of disease manifestation. Prostaglandins Leujot Essent Fatty Acids 1998;59:239-54.
4.- Sullivan BD, Cermak JM, Sullivan RD, et al. Correlation between nutrient intake and the polar lipid profiles of meibomian glands secretions in woman with Sjogren´s syndrome. Adv Exp Med Biol 2002;506:441-7.
5.- Viau S, Pasquis B, Maire MA, et al. No consequences of dietary n-3 polyunsaturated fatty acid deficiency on the severity of scopolamine-induced dry eye. Graefes Arch Clin Exp Ophthalmol 2011;249:547-57.
6.- Aragona P, Bucolo C, Spinella R, et al. Systemic omega 6 essential fatty acid treatment and pge 1 tear content in Sjogren´s syndrome patients. Invest Ophthalmol Vis Sci 2005;46:4474-9.
7.- Barabino S, Rolando M, Camicione P, et al. Systemic linoleic and gamma-linoleic acid therapy in dry eye syndrome with an inflammatory component. Cornea 2003;22:97-101.
8.- Creuzot-Garcher C. Lacrimal film and the ocular surface. J Fr Ophtalmol 2006;29:1053-9.
9.- Macri A, Giuffrida S, Amico V, et al. Effect of linoleic acid and gamma-linoleic acid on tear production , tear clearance end on the ocular surface after photorefractive eratectomy. Graefes Arch Clin Exp Ophthalmol 2003;241:561-6.
10.- Wojtowicz J, Butovich I, Uchiyama E, et al. Pilot prospective, randomized, double-masked, placebo-controlled clinical trial of an omega-3 supplement for dry eye. Cornea 2011;30:308-14.