Glaucoma and Your Diet

Old man having coffee or tea
Getty Images/Juanmonino

In eye health care, it is well established that nutrition plays a huge role in the treatment and management of some eye diseases. However, there has not been a tremendous amount of research on the subject of nutrition and glaucoma­­. However, some nutritional proponents state that there may be some benefit to taking certain nutritional supplements to either help treat glaucoma or reduce the risk for developing glaucoma.

Testing for Glaucoma

In the past, most glaucoma testing included a visual field study, eye pressure testing, and optic nerve studies. The standard of care today is to test much more including visual field studies, eye pressure testing, optic nerve studies, pachymetry (corneal thickness measurement), nerve fiber layer testing and blood pressure.  However, should we be looking at a patient’s nutritional status as well?

Elevated Eye Pressure

The biggest risk factor for the development of glaucoma is elevated eye pressure or what doctor’s call IOP or intraocular pressure.  By definition, glaucoma is a disease of the optic nerve in which nerve fibers die off due to elevated eye pressure. Over time, if not treated, people with glaucoma will have vision loss. In most cases, vision loss starts in the periphery of your vision and then encroaches on central vision if not controlled.

One aspect of glaucoma that confuses practitioners is that there seems to be a whole subset of people with higher than average pressures who seem never to actually develop symptoms of glaucoma.  The question becomes what makes some people develop glaucoma with elevated eye pressure while some can have quite high eye pressure and never develop glaucoma? Clearly, the relationship between elevated intraocular pressure and glaucoma is not linear.

Risks for Developing Glaucoma

Researchers feel that other mechanisms most come in to play. Vascular dysregulation and oxidative stress are two mechanisms that may lead to a higher risk of developing glaucoma. Researchers feel that nutrition could possibly have an effect at altering these two mechanisms to lower one’s risk of developing glaucoma.

Vascular dysregulation – Discussion of vascular dysregulation gets quite complex very fast. In short, it deals with blood pressure and the pressure needed to supply blood and oxygen to the optic nerve, the nerve cable that connects the eye to the brain. One study found significantly lower blood flow values in the blood vessels behind the eye in patients with African descent. African descent is one risk factor for developing glaucoma.

Oxidative stress – Cells in the retina require a great deal of energy. Because of this high energy requirement, there are a lot of byproducts that can be harmful to our cells. However, most people have enzymes that counter-act these harmful byproducts. Patients that do not have these enzymes have a higher chance of developing glaucoma. It seems prudent that increasing our anti-oxidant in-take, which is good for all kinds of health issues, will also lower the risk of developing glaucoma.

Nutrition and Glaucoma

Certain nutritional supplements are being studied that can target both vascular dysregulation and oxidative stress.

  • Ginkgo biloba – One study showed that ginkgo biloba given at only 40 mg given three times per day was enough to improve blood flow to the optic nerve. Ginkgo biloba shows promise because it is absorbed easily allowing it to work on the energy factories in our cells that are vulnerable oxidative stress. One must be very careful taking this supplement as it can increase bleeding and increase blood pressure in some people.
  • Black currant anthocyanins – This supplement has been shown to lower intraocular pressure and also increase blood flow to the optic nerve.
  • Mirtogenol – Mirtogenol is a bilberry extract and a bark extract was shown in studies to reduce eye pressure and increase blood flow. It also had a synergistic effect when taken with latanoprost, a common glaucoma medication. Mirtogenol does not cause any side effects that we know of at this time.
  • Manganese – Elevated levels of manganese in the blood is thought to decrease one’s risk of glaucoma.

Even coffee is being investigated as a helpful food supplement to people suffering from glaucoma because of its wonderful antioxidant properties. Although it is not yet the optometric standard of care, in the future, glaucoma testing may include blood testing to check certain levels of nutrients in the body. For now, those of us with a family history of glaucoma should pay attention to research in glaucoma and nutrition.

SOURCE: Review of Optometry, Nutrition, and Glaucoma: Exploring the Link, Reed, Kimberly, November 15, 2015, p 58-63

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