University of Western Sydney (UWS) student Chendur Palaniappan analysed his own tears to find clues to producing better and longer lasting lubricants to help millions of people with painful dry eyes. And the secret is in how proteins and oils interact, he found.
The stresses of modern life-smoke, air conditioning, staring at television and computer monitors without blinking-cause eyes to become sore and irritated. This condition, known as “dry-eye”, is the world’s fastest growing eye complaint. Globally one in five people, including half those over 65 suffer from the condition. It is difficult to treat because it has so many causes. Left untreated it can lead to infection and blindness.
“The key to the problem is to understand how tears spread across the eye surface and then stay there. In dry eye, this does not happen. The tears break up and evaporate quickly-within five seconds as opposed to 20 seconds normally,” says Chendur, a post graduate student in the School of Natural Sciences.
“The current solution is to use artificial tear drops. But they are expensive, don’t last long, and at best provide only temporary relief. To solve the problem I looked at the structure of tears,” he says.
Tears not just water, but contain a thin oily layer at the surface. The oils are released from small openings in the eye. It was previously thought they alone acted as a barrier to prevent breakdown and evaporation from the eye surface. But previous work at UWS unexpectedly found the outer oily layer also contains several different types of proteins and mucous.
It became clear that interactions between the proteins and oils in the tear film were the key to ensuring that tears spread over the eye surface and did not evaporate or break down. But how this happened remained a mystery.
“I collected samples of my own tears to extract the compounds needed for my experiments. It was a little uncomfortable at first but I got used to it. And it meant I never ran out of source material,” Chendur says.
From his own tears, Chendur isolated the proteins–lysozymes, lactoferrins and tear lipocalin-and evaluated their interaction with the oily layer. “The major proteins of the tear film bind with each other. It’s their combined interaction with the outer oily layer that leads to a more stable tear film,” he says.
It is believed these protein interactions could be responsible for the remarkable viscous and elastic properties that allow the tears to spread over the eye surface. “The tear film is spreadable and resistant to breakdown. It’s viscous like honey, yet elastic like a rubber band,” Chendur says.
Chendur’s research team is using high speed digital cameras and fluorescence microscopy to record how the molecules behave at the tear film surface, and to investigate how tears can last longer.
The ultimate goal is to use the knowledge of how tears work and how artificial compounds can interact with them to create eye drops that bring long lasting relief to the millions of people suffering from dry eye. The research could also be the key to understanding interactions of proteins at other surfaces in the body including cell membranes and lung films.
Chendur Palaniappan is one of 16 early-career scientists chosen for Fresh Science, a national program sponsored by the Federal and Victorian governments. He is presenting his research to the public for the first time at the Melbourne Museum.