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Is That Morning Cup of Coffee Good or Bad for Your Eyes?

The latest research on how caffeine affects five different eye conditions

spinner image a brown eye iris and pupil in coffee mug from overhead
gerenme / Getty Images

Over the past few years, the headlines about caffeine and eye health have been confusing, to say the least: “Too much caffeine may raise the risk of blinding eye diseases,” one headline blared. Meanwhile, another headline asked: “Can coffee protect our eyesight?”

It’s no wonder average people are confused.

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“We get this question [about caffeine] over and over again,” says Mina Massaro-Giordano, MD, professor of clinical ophthalmology at Penn Medicine.

Some 90 percent of Americans consume caffeine each day, whether from soda, tea, energy drinks or coffee. In fact, coffee consumption is at a 20-year high, with two out of three Americans grabbing a daily cup of joe, according to the National Coffee Association. At the same time, the number of Americans with major eye diseases is increasing, in large part because the population is aging.

Whether you already suffer from an eye condition or you simply want to prevent one, it’s important to know how your java habit impacts your eye health — and what you can do to lower your risk.

The good news is, although the research is mixed, moderate amounts of caffeine do not appear to increase the risk of eye disease for most people, Massaro-Giordano says.

However, your actual risk depends on a variety of factors including how much caffeine you drink, if you already suffer from an eye problem or if you are predisposed to one.

In general, Massaro-Giordano and other experts say their advice on caffeine is the same as it is for other aspects of your health: everything in moderation.

For healthy adults, the Food and Drug Administration recommends no more than 400 milligrams of caffeine a day — that's about four cups of coffee.

Read on for more specifics about the research on how caffeine affects different eye conditions:

1. Dry eye: Caffeine may help  

If you’ve developed dry eye — a common condition characterized by itchy and irritated eyes — you may worry that your daily pick-me-up could make things worse. After all, caffeine is believed to be a mild diuretic, meaning it forces more water from your body.

However, a 2022 study of 85,000 participants published in the journal Cornea found that caffeine consumption does not increase the risk of dry eye or make it worse.

In fact, the latest research reveals caffeine may actually improve the condition by stimulating the gland that produces tears, says Christopher Starr, an ophthalmologist at Weill Cornell Medicine in New York City.  

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Two placebo-controlled studies have shown that participants who were given caffeine produced more tears than those who were given only water or another placebo.

2. Glaucoma: Caffeine may increase risk — if you are genetically predisposed

Although caffeine is known to temporarily increase eye pressure, the latest studies indicate that most people who consume caffeine are not at increased the risk of glaucoma, a blinding disease caused by too much pressure in the eye.

However, a 2021 study published the journal Ophthalmology revealed that caffeine does increase the risk for those who have a family history of glaucoma or a genetic predisposition to the disease, said coauthor Anthony Khawaja, a glaucoma researcher at the University College London Institute of Ophthalmology in London and an ophthalmic surgeon at Moorfields Private Eye Hospital.

For those patients, the risk increases as much as three-fold if they consume caffeine, the study shows.

“If you've got a high genetic risk, it might be that limiting your caffeine consumption can help protect you,” Khawaja said. “And that's really interesting, because we're moving into a world where more and more now, we are finding out our genetic code.”

If you have a family history and want to know if you are at increased risk of glaucoma, you can ask your doctor about genetic testing. 

3. Eyelid twitch: Caffeine makes it worse

Most people have had occasional moments when their eyelids flutter or twitch involuntarily. Sometimes, the condition — called myokymia — can last for hours or days.

Too much caffeine is a common cause of myokymia, Starr says, especially if you’re also tired or under a lot of stress. How much is too much? Use the FDA recommended maximum of 400 milligrams a day as a general guide. But for this condition, fatigue and stress both play a role, so the amount may vary by person.

The good news is that the condition usually goes away on its own if you lower your caffeine consumption and reduce stress. If not, medications and Botox injections can help.

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4. Cataracts: Caffeine may help

Your daily cup o’ joe may not only wipe away your grogginess in the morning; a growing body of evidence indicates it may also help prevent cataracts.

A large study published in Clinical Ophthalmology in 2016 found that those who drank more coffee were significantly less likely to develop cataract blindness compared to those who drank less.

Researchers believe caffeine helps counter the effects of UV light on your eyes. “It helps with oxidative stress, and that’s what causes cataracts,” Massaro-Giordano says.

5. Retinal disease: Caffeine/coffee may help slow progression

The strong antioxidants in coffee may also help prevent or slow the retinal damage caused by aging and certain diseases, research shows.

One study, published in 2022 in Frontiers in Pharmacology, found that caffeine could potentially suppress the inflammatory response that causes retinal damage from age-related macular degeneration and diabetic retinopathy.

In another study, Korean researchers found that those who drank more than two cups of coffee a day had lower odds of diabetic retinopathy and vision-threatening diabetic retinopathy.

Those same anti-inflammatory properties are believed to be why coffee has been shown to reduce the risk of other diseases including Parkinson’s, diabetes and Alzheimer’s disease.

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