Consuming large amounts of caffeine increases the risk of glaucoma by more than 3 times for people genetically predisposed to high eye pressure.
The danger of coffee for eyesight was discovered by scientists from the Icahn School of Medicine.
Experts analyzed the records of more than 120 000 participants in the period from 2006 to 2010.
The volunteers were between 39 and 73 years old. They completed dietary questionnaires, noting how many caffeinated beverages they drink daily, as well as what caffeinated foods they consumed and in what portions.
Three years later, the participants had their intraocular pressure measured and their eyes examined.
In a quarter of the volunteers with the highest genetic predisposition to glaucoma, the love of coffee and caffeinated foods was associated with a high risk of developing IOP and glaucoma.
Specifically, consuming over 480 milligrams of coffee a day (4 cups of coffee) contributed to an eye pressure of 0.35 millimeters of mercury.
With high genetic risk, consumption of about three cups of coffee a day increased the risk of glaucoma by 3.9 times compared with those who drank little or no caffeine.
In glaucoma, intraocular pressure exceeds normal, resulting in irreversible visual defects, including decreased visual acuity, decreased visual field, and optic nerve atrophy. This disease leads to blindness.