Some research suggests a link between how much coffee you drink and your risk of developing glaucoma if you have a family history. But no evidence suggests that coffee causes glaucoma or blindness.

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A quick internet search of whether coffee causes blindness brings up many articles with alarmist and misleading titles.

Many of these articles reference statistics from a 2012 study by researchers at Brigham and Women’s Hospital, Harvard Medical School, and other research centers in the Boston area.

In this study, researchers found that adults who drank 3 or more cups of caffeinated coffee per day had a 66% higher risk of developing glaucoma than those who didn’t drink coffee.

Many news outlets misinterpreted this as meaning coffee causes glaucoma or blindness. But the results of the study didn’t find a cause-effect relationship, and more research is needed to understand the connection fully. Some other studies suggest that coffee may have benefits for your lens and retina.

Stay with us as we examine what the latest research has found about how drinking coffee affects your eyesight.

The relationship between coffee consumption and your eyesight is complex, and it’s likely that coffee affects people in different ways. Research from 2012 suggests drinking very large amounts of coffee may increase your risk of glaucoma, especially if you have a family history.

Glaucoma is a group of conditions characterized by damage to your optic nerve. It’s the second leading cause of blindness worldwide, with most cases occurring in developing countries. The most common type of glaucoma, primary open angle glaucoma, results in chronically high pressure in your eye.

What the research says

In the same 2012 study, drinking 3 or more cups of caffeinated coffee per day was linked to a higher risk of developing glaucoma. The link was strongest among women with a family history of glaucoma.

People who consumed 500 milligrams (mg) or more of caffeine per day trended toward having a higher risk of glaucoma than people who consumed less than 125 mg of caffeine per day. But the difference wasn’t statistically significant.

In a 2021 study, some of the same researchers evaluated the risk of glaucoma in over 120,000 regular coffee and tea drinkers. They didn’t find a relationship between drinking coffee and glaucoma overall. However, they did find an increased risk in people who consumed more than 321 mg of caffeine per day and whose genes made them more likely to have higher eye pressure.

In a smaller 2020 study using data from South Korea, researchers found a link between drinking coffee and the risk of glaucoma in men but not women.

Some research suggests that caffeinated coffee may increase pressure in your eye. It may also increase levels of an amino acid called homocysteine, which is associated with an increased risk of glaucoma.

There’s also increasing evidence that caffeine constricts the blood vessels in your eye and reduces blood flow. This reduced blood flow may increase the risk of optic nerve damage from glaucoma.

Who’s at risk for glaucoma?

Risk factors for glaucoma include:

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Some evidence suggests drinking coffee is linked to a decreased risk of cataracts. Cataracts are cloudy areas that form over your lens. They’re the leading cause of blindness worldwide.

Although researchers are still studying the connection, caffeine may inhibit oxidative stress in your lens.

A 2019 rodent study found evidence that caffeine and a chemical called pyrocatechol generated through the roasting of coffee beans may be key components of coffee responsible for protecting the lens.

Emerging research suggests that caffeine may also be protective against retinal inflammation and might be a future candidate for treating retinal disease.

In a February 2023 study, researchers found that higher caffeine intake was linked to a slightly lower risk of dry eyes. They didn’t find a link when they adjusted their data for pre-existing health conditions.

To maintain your eye health as you age, consider the following tips:

  • Undergo regular eye exams according to the schedule recommended by the American Optometric Association.
  • Eat a balanced diet and exercise regularly to prevent diabetes.
  • Eat plenty of dark leafy greens and fatty fish.
  • Find out if you have a family history of eye disease.
  • Protect your eyes when playing sports and activities with a high risk of eye injury.
  • Wear sunglasses when out in the sun.
  • Avoid smoking, or try to quit if you currently smoke.
  • Take regular breaks from your computer screen to reduce eyestrain.

Research is mixed on whether drinking coffee increases your risk of glaucoma, a leading cause of blindness. The strongest evidence suggests that drinking very high amounts of caffeine may increase the risk of glaucoma in certain people with a family history.

Some evidence suggests that coffee may help protect your eyes against cataracts or retinal damage. More research is needed to understand the relationship.