High eye pressure: what to eat to lower it?

Nutrition can prove to be a valuable ally of vision. What, then, to put on your plate when your eye pressure is high? Among the ingredients to favor are sources of omega-3s and carotenoids. Two, in particular, are needed by the eyes: lutein and zeaxanthin. Let's find out what their main sources are.

Ocular (or, rather, intraocular) pressure is the pressure of the fluid inside your eye. In fact, you can imagine this organ exactly as if it were a balloon containing water: if it were not full enough, it would droop; adequate pressure from the inside out, exerted precisely by the water, on the other hand, allows it to stay in shape. However, this pressure must not be excessive, or risk damage that can seriously impair vision.

The limit not to be exceeded is 21 mmHg; otherwise, the eye may develop a form of glaucoma-which is one of the leading causes of blindness in the world. But high eye pressure is not enough to diagnose the disease: in the absence of damage to the optic nerve (the one that transmits nerve signals from the retina to the brain) and signs of glaucoma or other eye diseases, it is more simply called ocular hypertension.

While not a disease, ocular hypertension should not be neglected, even if it affects only one of the eyes. But how to lower eye pressure? Are there natural remedies to lower high eye pressure, or are medications the only allies to keep it under control? Is there, for example, a link between eye pressure and nutrition that can be exploited to limit the risks associated with any elevations above 21mmHg?

High eye pressure: what does it depend on?

Precisely because an increase can seriously damage structures within the eye, intraocular pressure is carefully regulated by a fluid drainage system that keeps it within acceptable levels ("normal" ocular pressure is between 10 and 21 mmHg). However, it can happen that there is an imbalance between the production and drainage of fluid in the eye, and this can raise the pressure inside the eye-just as would happen inside a balloon where water is added.

This fluid is produced by cells located in the posterior part of the anterior eye; after accumulating in the posterior chamber it flows to the anterior chamber passing through the pupil. From the anterior chamber it then flows into veins that drain it outside the eye, while only a small amount returns to the posterior chamber by passing through the iris. Its secretion is regulated by the sympathetic nervous system; it is, then, the intraocular pressure itself that stimulates phenomena that ultimately lead to drainage of the fluid outside the eye.

Here, then, is what affects ocular pressure: first of all, the proper drainage of the fluid in the eye. Next, it is known that as we age, intraocular pressure slowly increases; therefore, the risk of ocular hypertension increases after the age of 40. Other risk factors for ocular hypertension and its most dreaded complication (which, as mentioned, is glaucoma) are high blood pressure (hypertension) and, at the same time, too low a pressure (hypotension), diabetes, severe myopia, a thin cornea, bleeding at the optic nerve, trauma or surgery to the eye, prolonged intake of steroids, certain specific diseases (pigment dispersion syndrome and pseudoexfoliation), and stress.

When is ocular pressure dangerous high?

Early-onset cases of ocular hypertension are of particular concern, because an eye exposed to high pressure for so many years has a greater chance of being damaged. Any increases, however, should not be taken lightly at any age. In fact, a sudden rise in intraocular pressure can always stress the optic nerve fibers. If, then, this increase remains constant, the eye pressure can contribute to the development of what is known as primary open-angle glaucoma.

The latter is a chronic degeneration of the optic nerve. Its link with ocular hypertension could depend on mechanical damage or alteration of the associated cells and blood vessels, which seem to be promoted precisely by the increased pressure inside the eye. For its part, on the other hand, the increased intraocular pressure that leads to glaucoma appears to be associated with the malfunctioning of the mitochondria (the organelles within the cell that are responsible for energy production) and oxidative stress.

What are the symptoms of eye pressure high?

Open-angle glaucoma is a progressive disease in which the effects of optic nerve damage can take a long time to manifest. What is more, in most cases high eye pressure is not associated with particular symptoms. Only rarely is it possible to feel pain in the eyes by moving or touching them. In contrast, there is no association between high eye pressure and headaches or between high eye pressure and dizziness.

The absence of symptoms should not make one underestimate the risks of high eye pressure. Precisely because glaucoma is a slow and progressive disease, even if the optic nerve is not yet damaged and vision is not yet impaired, it is a good idea to undergo appropriate checkups to manage the situation as best as possible and thus reduce the risk of visual field impairment.

What to do in case of high eye pressure?

The best approach to the management of ocular hypertension is careful monitoring of the pressure within the eye, to be combined with assessment of the presence of any damage to the optic nerve and other structures and verification of visual acuity. It is therefore essential to undergo all scheduled eye examinations.

Some cases may require treatment with medication. The goal is to lower the pressure before vision pays the price. It will be the ophthalmologist who will assess the need for drug treatment, with a view to individualized management; in particular, the choice of whether or not to use drugs will depend on the risk of developing glaucoma, the presence of signs of optic nerve damage, and the balance of advantages and disadvantages of treatment.

The use of surgical treatment is rarer; in the case, laser is usually used.

What to eat to lower eye pressure?

There is no specific diet for lowering eye pressure. However, a healthy and balanced diet helps to protect, in general, eye health. Foods to favor undoubtedly include fish - a source of Omega-3s, allies of vision - and fruits and vegetables, especially green leafy vegetables (such as kale and spinach), a source of carotenoids that are allies of vision.

The benefits of Omega-3 for eyesight are certified by Efsa (the European Food Safety Authority), according to which docosahexaenoic acid (DHA, one of the Omega-3s in fish) "contributes to the maintenance of good visual abilities." Not coincidentally, the retina of the eye is rich precisely in DHA. To get your fill of it at the table, it is good to eat fatty fish, such as salmon, mackerel, anchovies, sardines, sardines and tuna; in case of increased need, allergies or a diet that excludes fish by ethical choice, it can be taken in the form of dietary supplements (remember: there are also sources of DHA suitable for those who cannot or do not want to eat fish).

As for carotenoids, however, those found in food and going into the eye are lutein and zeaxanthin, which, unlike the well-known beta-carotene, are not vitamin A precursors. By themselves, lutein and zeaxanthin do not help lower intraocular pressure; however, they appear to be useful in the management of glaucoma because of their strong antioxidant properties.

A review of studies published in the scientific literature that appeared in the pages of Nutrients in 2021 showed an association between a diet rich in carotenoids and reduced risk of glaucoma; in addition, higher levels of carotenoids in the macula (the central part of the retina, which is very important for image perception) is associated with better visual abilities in eyes affected by glaucoma. More specifically, lutein has been associated with neuroprotective effects exerted at the level of the retina.

As mentioned, spinach and kale are rich sources of lutein and zeaxanthin; following a diet richer in these vegetables for at least 4 weeks has been associated with a 4-5% increase in pigment optical density in the macula. Other foods to fill up on include broccoli, peas, lettuce, egg yolk, parsley, and durum wheat. As with Omega-3s, for an extra dose, or to meet increased needs, dietary supplements can also be relied upon; their intake, when continued for sufficient periods (140 days), has been associated with a significant increase in circulating levels of lutein in the body.

Other nutrients allied to vision are the aforementioned vitamin A, abundant in both plant (such as carrots and apricots) and animal (particularly liver) foods; vitamin B12, typically found in foods of animal origin; and zinc, abundant in nuts, meat and fish. A varied diet, which does not exclude any food group, allows for good intakes of these molecules as well. Not only that, a healthy, balanced diet without excess salt also keeps certain risk factors for ocular hypertension (such as high blood pressure and diabetes) at bay.

High eye pressure: what to avoid?

In contrast, to protect eye health, it is good to avoid tobacco smoke. In the particular case of ocular hypertension, there is food for thought about the link between increased pressure and oxidative stress, which is known to be promoted by smoking itself.

Bibliographical references

Abdel-Aal el-SM, Akhtar H, Zaheer K, Ali R. Dietary sources of lutein and zeaxanthin carotenoids and their role in eye health. Nutrients. 2013 Apr 9;5(4):1169-85. doi: 10.3390/nu5041169

Cleveland Clinic. Ocular Hypertension. Last viewed: 4/30/24

European Community. Eu Register of Health Claims. Last viewed: 30/04/24

Lem DW, Gierhart DL, Davey PG. Carotenoids in the Management of Glaucoma: A Systematic Review of the Evidence. Nutrients. 2021 Jun 6;13(6):1949. doi: 10.3390/nu13061949

Machiele R, Motlagh M, Patel BC. Intraocular Pressure. [Updated 2022 Jul 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532237/

Salgle G, Montelongo M, Chu l, Mojica S. Carotenoid Supplement Use and IOP Control in Glaucoma Patients. ARVO Annual Meeting Straccar. June 2020. Available from: https://iovs.arvojournals.org/article.aspx?articleid=2768458