Too much caffeine can lead to blindness in people at high-risk for glaucoma

NEW YORK — Caffeine can be a major pick-me-up for many people needing a boost and to keep their eyes open. Unfortunately, a new study finds drinking too much coffee or other caffeinated beverages may come at a serious cost to your eye health. Researchers from the Icahn School of Medicine at Mount Sinai say caffeine drinkers with a higher genetic risk for glaucoma are nearly four times more likely to develop the blinding eye disease.

Study authors add their findings are the first to reveal a link between a person’s diet and the vision-robbing condition. Glaucoma is the leading cause of blindness in the United States. No matter what type of glaucoma a patients has, the results are the same. High eye pressure damages the nerve which connects the eye and brain, leading to increasing vision loss and eventually blindness.

Currently, the main treatments for glaucoma include medicated eye drops and surgery.

How many cups of coffee will impact vision?

An international team examined over 120,000 people, looking at the connections between caffeine intake and intraocular pressure (IOP) — a key measure of pressure in the eyes and a patient’s overall risk for glaucoma. For patients with elevated IOP, they typically have no symptoms until the disease begins to affect their eyesight.

Overall, results show regularly drinking high amounts of caffeine does not have a tremendous impact on IOP and glaucoma risk. However, among people who have the highest genetic risk of developing elevated IOP, drinking three cups of coffee daily led to a nearly four-fold spike in glaucoma cases.

“We previously published work suggesting that high caffeine intake increased the risk of the high-tension open angle glaucoma among people with a family history of disease. In this study we show that an adverse relation between high caffeine intake and glaucoma was evident only among those with the highest genetic risk score for elevated eye pressure,” says corresponding author Louis R. Pasquale, MD, FARVO, Deputy Chair for Ophthalmology Research for the Mount Sinai Health System, in a media release.

It takes less caffeine to cost a glaucoma patient their sight

Researchers analyzed DNA samples and health records from 2006 to 2010 for a group in the UK Biobank, one of the world’s largest medical databases. The group, between ages 39 and 73, also provided information about their caffeine habits, including how much they drink each day, how much caffeine-rich food they eat, and the times they consume these products. Additionally, participants revealed their family histories of glaucoma or other vision problems.

Three years into the study, the team checked each patient’s eye pressure again. For people who drank the most caffeine, 480 milligrams or roughly four cups of coffee a day, their IOP increased by an average of 0.35 mmHg.

Participants in the top 25 percent in terms of genetic risks for glaucoma however, were affected much more severely by daily caffeine consumption. Study authors discovered 321 milligrams of daily caffeine, about three cups of coffee, increased glaucoma prevalence by 3.9 times in these individuals.

“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,” says study co-author Anthony Khawaja, MD, PhD, from the University College London Institute of Ophthalmology. “The UK Biobank study is helping us to learn more than ever before about how our genes affect our glaucoma risk and the role that our behaviors and environment could play. We look forward to continuing to expand our knowledge in this area.”

The findings are scheduled to appear in the June issue of Ophthalmology.

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