Can excessive caffeine consumption cause blindness?

Switching to decaf could save your sight, claims the Daily Mail. The newspaper reports that drinking three or more cups of coffee a day is linked with vision loss and blindness.

The story is based on a study that looked at the association between caffeine consumption and exfoliation glaucoma. Exfoliation glaucoma is a condition in which fluid builds up inside the eye, putting pressure on the optic nerve. This leads to a degree of sight loss and, in serious cases, total blindness.

In the study, researchers compared rates of exfoliation glaucoma with drinking habits, focusing on caffeinated drinks such as coffee, tea and cola.

The study found that drinking three or more cups of caffeinated coffee daily was linked with increased risk of developing exfoliation glaucoma. Curiously, a similar increase was not found with other caffeinated products.

This was a large, well-conducted study, but it does not directly or conclusively show that caffeinated coffee causes vision loss. This is because it relied on people recalling their coffee intake over long periods and involved relatively few people with the condition.

By far the greatest risk of exfoliation glaucoma was among those with a family history of glaucoma – which is a factor already known to be linked with developing glaucoma.

Coffee has been linked in the past with both health problems and health benefits. So, despite the headlines, there’s no need to ditch the cappuccino altogether, but it makes sense to drink coffee and other caffeinated products in moderation.