In previous articles we have pointed out the importance of nutrition and chronic stress as the main cause of many diseases. Oxidative stress is produced, with an increase in the levels of free radicals, which would be the pathogenic basis of various general and ocular diseases. ¹as the cataracts, age-related macular degeneration, glaucoma and the syndrome of dry eye and nutrition.

Ophthalmologists and nutritionists must collaborate for their treatment.

Oxidative stress is characterized by 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 their concentration increases due to the fact that endogenous and exogenous antioxidants cannot eliminate them properly. The consequences of stress Oxidative is the appearance of generalized inflammation that affects all the tissues of the body and especially the eyes.

Nutrition and dry eye

One of the consequences of the relationship between poor nutrition and dry eye is the inflammation of the lacrimal glands, of the meibomian glands of the Eyelids (figure 1) and the ocular surface. This inflammation is responsible for a decrease in tear production, alterations in its composition due to lipid deficiency (the fat secreted by the meibomian glands), which lubricate the eyeball and also form the outer layer of the tear film (figure 2), which prevents its evaporation and thus prevents the tear film from breaking (figure 3) and drying out the ocular surface.

These alterations are responsible for the fact that in the blink there is a continuous friction on the cornea, that the osmolarity of the tear is increased and more inflammation is generated, effects that add up, damaging the tissues continuously and progressively. It's a vicious cycle centered around inflammation.

Figure 1.- Meibography of the upper eyelid with absence of Meibomian glands (blue arrows).

Figure 2.- Analysis of the tear lipid layer by interferometry. Iridescent areas of lipids (blue stars) are visible.

Figure 3.- Non-invasive videokeratography of tear film tear time, showing the break areas (arrow) and the break time graph (star).

There is increasing evidence pointing to the importance of the nutritional factor in the inflammatory basis of the Dry Eye.

Perhaps the most significant study corresponds to the Women's Health Study ², where 39.876 women are analyzed and the relationship between diet and the presence of dry eye is verified. When the diet was rich in omega 3 fatty acids and low in omega 6, the incidence of dry eye was low, while when omega 3 decreased and omega 6 increased, the incidence of dry eye skyrocketed.

Omegas and dry eye

Other studies also show how 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 its appearance in the population at risk, such as postmenopausal women, older 65 years old ³. In the same line of research it was evidenced that the composition of the lipids of the meibomian and tear glands was abnormal in low diets in omega 3 and with an excess of omega 6, normalizing when food intake was corrected, enhancing the omega 3 and reducing the omega 6 ^4,5.

Omega 3 and dry eye

This is a key factor between dry eye and nutrition The beneficial action 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 Sjogren's, processes rheumatic or autoimmune type. The inflammation of the ocular surface will be responsible for the subjective discomfort that patients notice, as well as the triggering factor for the tissue damage to advance and the dry eye condition to worsen.

A breakthrough in this campor is the fact of having a test, very simple to apply, that detects inflammation (metalloproteinases 9) and that guides us for diagnosis and treatment. One of the problems that arise is that we can not use anti-inflammatory drugs for a long time, so it is so effective to rebalance the diet by boosting omega 3, reducing omega 6 and increasing the intake of antioxidants.

Take omega 3 for the eyes

A very important and little known aspect when we talk about diets rich in omega 3, is the fact that the foods we eat, and especially the supplements rich in omega 3, degrade when they enter the body, undergo an oxidation process 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 pointing to the combination of omega 3 with antioxidant supplements such as vita C and E and polyphenols, present in dark chocolate and red wine, with great antioxidant capacity and that enhance the action of omega 3.

Diet and dry eye

For the dry eye treatmentThrough effective control of diet and stress, it is important to know the oxidation status of each patient, their level of free radicals, the cortisol curve and DHEA as well as the levels of omega 3 and omega 6 in the red blood cells . Currently, the levels of these biomarkers can be detected to adjust the appropriate therapeutic measures in each case. We have seen that general recommendations are not enough. The data we obtain with these analyzes allow us to adjust the treatment and, very importantly, allows us to better assess the effectiveness of the measures we have taken.

REFERENCES

1.- Richer SP, Rose RC. Water soluble antioxidants in mammalian aqueous humor: interaction with UV B and hydrogen peroxide. Vision 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 immunological 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 women 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 Ophthalmol 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.