Caffeine & Eye Pressure

Cup of hot coffee
Coffee is a major source of daily caffeine consumption. (Image: AlexRaths/iStock/Getty Images)

Caffeine does more than just boost energy levels. It can also increase pressure within the eye. This is concerning, because high eye pressure over time can lead to glaucoma, a potentially blinding disease of the optic nerve. Whether or not this pressure increase will have long term visual effects depends largely on a person’s genetics and family history of glaucoma. (see references 1 & 2)

Caffeine Consumption

Caffeine is a major component of commonly consumed beverages such as coffee, tea and soda and is found in foods such as chocolate candy or cake. (see reference 3) Just one cup of coffee (approximately 230ml) contains 150 to 180mg of caffeine (see references 1 & 3). It is estimated that individuals consume over 200mg of caffeine daily in the United States and over 400mg a day in Europe. (see reference 3) One study published in Eye showed that after 60 minutes of ingesting 1 cup of caffeinated coffee, the intraocular pressure increased by 1 mmHg. The majority of the study participants were Caucasian and ranged in age from 40 to 80 years old. (see reference 1)

Mechanism of Action

Caffeine elevates intraocular pressure in several ways. It directly increases production of aqueous humor, the fluid that fills the front part of the eye. Increases in this fluid increase the eye pressure. Caffeine also decreases smooth muscle tone. This slows down the rate at which aqueous humor is filtered out of the eye. Further, aqueous fluid formation is also stimulated through caffeine’s blood pressure- elevating effects. However, for every 1 mm Hg increase in eye pressure that caffeine produces, there is an equal 1mm Hg increase in ocular perfusion pressure, or the rate at which aqueous is released from the eye. This, in effect, negates the pressure increase ( see references 1 +2)

Glaucoma Risk

Primary open angle glaucoma (POAG) is a disease whereby the optic nerve is slowly damaged over time. It is a major cause of blindness throughout the world. Studies on caffeine effects have shown that people with naturally higher eye pressure showed a higher elevation in their eye pressure with caffeine ingestion. West Africans who have a genetic predisposition to developing glaucoma, had higher transient eye pressure spikes at lower levels of caffeine (30-50mg). Another study reviewed the effects of caffeine through food/drink consumption over a twenty year period. It found that although caffeine itself is not associated with glaucoma risk, it did increase the risk among people with a family history of glaucoma. (see reference 2)

Lifestyle Modification

Because high intraocular pressure is a major risk factor for the development of glaucoma, understanding what causes eye pressure to rise is key in lowering the chances of developing this disease. Halting coffee or tea consumption would be an easily modifiable lifestyle choice if doing so lowers glaucoma risk. However, based on study results so far, further investigation is needed regarding how a person’s genetics, family history and race may play a role in how their eye pressure responds to caffeine. If you have a family history of glaucoma or you have high eye pressure, you should visit with your ophthalmologist to discuss your caffeine use and potential risk of developing glaucoma. (see references 1 & 2)

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