Find out the secret of tears

We shed tears when we were sad, angry or touched, but so far people still don't know much about its structure. A recent study showed that every tear is made up of water, mucus and many fatty acids.

These findings, published in the January issue of the Journal of Investigative Ophthalmology & Visual Science , may help scientists find effective treatments for dry eye - a condition that affects hundreds million people worldwide.

A research team at Ohio University (USA) said that each tear is made up of three layers. The outermost is fat with the main component of lipid. Next is a layer of mucus and the inside is pure water. Every time we blink, the outer layer will cover the front of the eye to maintain moisture.

Why do we cry?

Researchers have identified the substances that make up the fat layer and are surprised to discover a type of lipid that has never been known as fatty acid amides, Kelly Nichols, eye specialist at Ohio University, said. .

They also found oleamide - a type of lipid that only occurs in the brain and central nervous system. Oleamide is thought to have a function to control sleep and communication between nerve cells. Scientists claim that it can control communication between cells in the front part of the eye.

If there is not enough or too much oleamide - or any fat - the outer fat layer of tears loses its ability to retain moisture, causing dry eyes, Nichols said.

Why do we wink?

Dry eye disease, Nichols explains, is caused by many factors. Symptoms of the disease include pain, burning, dryness and excessive tears. People with the disease may also have decreased vision.

"Tears create a smooth, smooth refracting surface so that light can pass easily. Therefore, if the frontal area is not smooth, our vision will decrease , " she said.

According to Nichols, people wearing contact lenses are at higher risk of dry eye. The risk in women is higher than that of men. She believes that this finding could help scientists find a way to test dry eye by monitoring it on the screen someday."The doctor just needs to sample your tears, then press a button, then look at the composition of the tears to tell you if you have dry eyes and if so, how to treat them," she said.

Viet Linh