A new study appearing in the Journal of Agricultural and Food Chemistry has found that the healthful substances in green tea can penetrate the tissues of the eye and potentially help fight eye diseases such as glaucoma.

Researchers in China conducted experiments on laboratory rats that had been given green tea. Analysis of the animals’ eye tissues showed that eye structures absorbed significant amounts of individual catechins, which are the protective antioxidants found in the tea that include lutein, zeaxanthin as well as vitamins C and E.

They found that the retina, for example, absorbed the highest levels of gallocatechin, while the aqueous humor tended to absorb epigallocatechin. The effects of green tea catechins in reducing harmful oxidative stress in the eye lasted for up to 20 hours.

"Our results indicate that green tea consumption could benefit the eye against oxidative stress," the report concluded.

Green tea has been used for medicinal purposes in China for thousands of years. Recent research has confirmed its usefulness in treating and preventing several conditions including rheumatoid arthritis, high cholesterol, cardiovascular disease and some types of cancer.