An emerging study adds another benefit of why eating green leafy vegetables is necessary. Scientists from Brigham & Women's Hospital and Harvard Medical School in Boston found that green leafy vegetables can potentially lower the risk for glaucoma.

According to researchers, people who consume food rich in nitrate — found in green leafy vegetables such as spinach, kale and lettuce as well as other sources like beets and carrots — have a 20 to 30 percent lowered risk of developing primary open-angle glaucoma, the most common type that usually leads to loss of vision.

The scientists studied the diet and eye exam results of about 64,000 women and 41,000 men from 1984 to 2012. All participants were beyond 40 years old, with mean age of 66.8 years, and were not diagnosed with glaucoma prior to the study.

Every 2 years for over 25 years, they submit themselves for eye examinations. A total of 1,483 participants have acquired the disease.

Scientists depend on questionnaires and medical records to confirm its occurrence. When the researchers evaluated the dietary intake of the participants, they found a 20 to 30 percent lowered risk for glaucoma.

Furthermore, they also discovered that it can also decrease likelihood for paracentral visual field loss, a particular type of glaucoma that disrupts blood flow autoregulation, for up to 40 to 50 percent.

Primary open-angle glaucoma is a severe damage of the optic nerve that progresses over time. It involves increased intraocular pressure and diminished optic nerve blood flow autoregulation. Manifestations include gradual loss of visual field and peripheral vision, which may eventually lead to blindness if left untreated.

According to researchers, if these results are proven in observational and intervention studies, this can have significant public health implications. Nevertheless, scientists pointed out that it still needs further research to determine the causal relationship between nitrate-rich diet and glaucoma.

The journal JAMA Opthalmology published the research spearheaded by Jae Kang.