Photo/Illutration A cup of coffee (Asahi Shimbun file photo)

KYOTO--A new study is casting doubts on the notion that drinking coffee might lead to worse eye health.

Researchers at Kyoto University performed an eye-health analysis of about 9,000 people, and the results suggest there is no need to refrain from enjoying a cup of joe out of fear of glaucoma or other eye disorders.

They found that habitual coffee drinkers, in fact, tend to have lower eye pressure than non-drinkers, although the reason has yet to be determined.

But experts do not recommend consuming coffee for the purpose of prevention or medical treatment.

“We will continue with our research, as the rate of glaucoma development and other data will be revealed through follow-up studies,” said Masahiro Miyake, a special assistant professor of ophthalmology at the university.

The research started after a patient asked an eye doctor whether coffee is bad for the eyes, but the doctor could not find a clear answer. 

It inspired scientists to examine the relationship between coffee intake and intraocular pressure, which is an indicator of eyeball hardness. Lower pressure suggests better health prospects, whereas abnormally high pressure is one of the causes of glaucoma.

The researchers asked 9,418 people, who were sampled because they are not glaucoma patients that are using eye lotion to reduce intraocular pressure, how often they drink coffee. The data was combined with their intraocular pressure levels measured at a health screening.

The study participants were not classified based on what kind of coffee they consume, such as regular, instant or canned.

The findings showed those who drink coffee three or more times a day have lower eye pressure than people who drink the beverage less than once a day. The difference in their eye pressure was comparable to about 3 percent of average intraocular pressure.

The more frequently a person ingested coffee, the lower their intraocular pressure.

But the study comes with big caveats.

The jury is still out on whether drinking coffee will reduce intraocular pressure. On top of that, even people with healthy levels of eye pressure can still develop glaucoma.

The scientists said patients should therefore not rely on a coffee break to prevent or cure eye problems.