Can a cup of hot tea every day keep glaucoma away?

New York: Your morning cup of tea may have more power than you thought. Researchers have found that drinking a cup of hot tea at least once a day may lower the risk of developing glaucoma, one of the leading causes of blindness worldwide.

Glaucoma causes fluid pressure to build up inside the eye, damaging the optic nerve. It currently affects 57.5 million people worldwide, and is expected to increase to 65.5 million by 2020.

The study, published online in the British Journal of Ophthalmology, found that compared with those who did not drink hot tea every day, those who did, had a lower glaucoma risk.

The new findings show that lifestyle changes could help prevent vision loss from glaucoma, lead study author Anne Coleman of the University of California, Los Angeles, was quoted as saying by Live Science.

However, the researchers noted that this was an observational study, and therefore, no firm conclusions can be drawn about cause and effect.

"Further research is needed to establish the importance of these findings," the researchers said.

The researchers looked at data from a National Health and Nutrition Examination Survey (NHANES) in the US. 

This is a nationally representative annual survey of around 10,000 people that includes interviews, physical examinations and blood samples, designed to gauge the health and nutritional status of US adults and children.

The survey also included eye tests for glaucoma. Among the 1,678 participants who had full eye test results, including photos, 84 (five per cent) adults had developed the condition.

They were asked how often and how much they had drunk of caffeinated and decaffeinated drinks, including soft drinks and iced tea, over the preceding 12 months, using a validated questionnaire.

The researchers found that hot tea drinkers were 74 per cent less likely to have glaucoma.

But no such associations were found for coffee -- caffeinated or decaffeinated -- decaffeinated tea, iced tea or soft drinks.

Tea contains antioxidants and anti-inflammatory and neuroprotective chemicals, which have been associated with a lowered risk of serious conditions, including heart disease, cancer and diabetes, the researchers said.

And previous research has suggested that oxidation and neurodegeneration may be involved in the development of glaucoma, they added.