Too Much Caffeine May Put Some People At Risk Of Blindness

For people who are genetically prone to high eye pressure, drinking high levels of caffeine every day may drastically increase the risk of glaucoma. That's according to a new study led by Mouth Sinai's Icahn School of Medicine, which notes that glaucoma is the top cause of blindness in the United States. In this case, a high level of caffeine meant around four or more cups of coffee daily.

Glaucoma is a disease that involves an increase in pressure in the eye, which can cause damage that eventually leads to blindness. Some people have a genetic risk for glaucoma, meaning that, for example, they may have parents or grandparents who suffered from this eye disease.

The new study found that those who were at the greatest genetic risk of the disease were also more likely to experience increased eye pressure as a result of high caffeine consumption. High consumption refers to more than 480mg of caffeine every day, which can come from a variety of sources: coffee, caffeinated teas, energy drinks, and even energy tablets that feature caffeine.

The risk factor is apparently greater for those at the top of the genetic risk group; in that case, more than 321mg of caffeine daily was linked to 3.9 times greater risk of glaucoma compared to people who had low genetic risk and those who consumed little or no caffeine.

The study's co-author Anthony Khawaja, MD, Ph.D., said:

Glaucoma patients often ask if they can help to protect their sight through lifestyle changes, however this has been a relatively understudied area until now. This study suggested that those with the highest genetic risk for glaucoma may benefit from moderating their caffeine intake. It should be noted that the link between caffeine and glaucoma risk was only seen with a large amount of caffeine and in those with the highest genetic risk.