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New study: How caffeinated coffee affects eyesight

Posted May 7, 2014

In almost every part of the world people can be found sitting together in coffee houses enjoying their favorite coffee drink – the experience of meeting for coffee has become popular in social interactions. Coffee seems to be the standard drink next to water around the world and coffee statistics shows that this drink is the most popular beverage worldwide with over 400 billion cups consumed each year.

Coffee. Image credit: Kenny Louie, Vancouver, Canada. Via Flickr, CC BY 2.0

Coffee. Image credit: Kenny Louie, Vancouver, Canada. Via Flickr, CC BY 2.0

In recent years, coffee drinkers were happy to find out that their habit isn’t so bad after all. But now we can find many arguments that caffeine causes insomnia, headaches, abnormal heart rhythms; too much caffeine can make us restless or irritable. New study has found another negative health effect of coffee – heavy caffeinated coffee consumption is associated with an increased risk of developing exfoliation glaucoma.

A group of researchers at Harvard School of Public Health had the aim to find the link between caffeinated coffee and exfoliation glaucoma. What is really interesting and surprising is that the authors of this study suggested that people who consume heavy amounts of caffeine put themselves at a higher risk of losing their vision. How did they find this consequence?

What is Glaucoma?

Glaucoma is a group of diseases that can damage the eye’s optic nerve and retinal fibers resulting in a progressive, permanent loss a vision and blindness. It is one of the main causes of blindness in the United States. Typically, this damage results from increased pressure within the eye, usually due to fluid buildup. However, early detection and treatment can slow, or even halt the progression of the disease.

Exfoliation glaucoma is a secondary type of glaucoma, and in this type of glaucoma there is a white fibrillary material that can actually cover the lens, go on the iris or the colored part of your eye or also in the drainage system of the eye, and it physically blocks the fluid from actually leaving the eye. On the average across the globe, it is the most common identifiable cause of glaucoma worldwide, and in some countries accounts for the majority of glaucoma cases.

How was the study conducted?

The scientists analyzed the health and medical profiles of 79,120 women in the Nurses’ Health Study and 42,052 men in the Health Professionals Follow-up Study, who were 40 and above years old. Participants were followed up for at least 18 years, in whom comprehensive dietary histories were assessed multiple times, to examine the relation between caffeine consumption and risk of primary open-angle glaucoma. Primary open-angle glaucoma is called wide-angle glaucoma, this is the most common type of glaucoma. The structures of the eye appear normal, but fluid in the eye does not flow properly through the drain of the eye. All of participants did not have this type of eye-related damage.

The research team used questionnaires to obtain and validate the consumption of beverages containing caffeine. Firstly, they asked participants all about their lifestyle habits, addictions (cigarette smoking and drinking alcohol) including caffeine consumption, then compared them to their medical records if they reported a history of glaucoma, looking specifically for diagnoses of exfoliation glaucoma. Besides, they asked to report their average intake of a serving of a food or beverage over the preceding year.

An analysis of the data from this research showed that the volunteers, who consumed three cups of caffeinated coffee a day, had an increased risk of developing exfoliation glaucoma or exfoliation glaucoma suspect, when compared to those who drank no caffeinated coffee at all. And, interestingly, the researchers did not find any correlations with consumption of other caffeinated products, such as soda, chocolate or tea, as well as decaffeinated coffee.

This study was the first study to find the link between caffeinated coffee and exfoliation glaucoma in the U.S., but the fact is that the researchers perfectly revealed a high incidence of vision problems among men and women who drank couple of strong cups of coffee per day.

Health findings surrounding coffee consumption are mixed: many researchers have reported findings that coffee drinking is associated with a lower risk of depression among women, a lower risk of lethal prostate cancer among men, and a lower risk of stroke. But coffee doesn’t have just a good side, it also has negative effects, which may include higher blood pressure, making arteries stiffer, increasing levels of homocysteine and has a link with vision loss and blindness. The negative effects of coffee tend to emerge in excessive drinking so it is best to avoid heavy consumption. The researchers mentioned that a couple of cups a day are not going to pose a serious risk to your eyesight.

Sources and further reading: iovs.orgScienceDaily,, TheAtlantic, NYDailyNews, DailyMail, MedicalNewsToday,,

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