Not a dry eye in the house

What are tears made of?

A new understanding of the composition of tears, based on work by a young Sydney researcher, may bring relief to the millions of people worldwide who suffer from the eye irritation, constant blinking and sensitivity to wind, smoke or air conditioning known as ‘dry eye’.

Tears are not just water. During each blink of the eye, water is mixed with oil and mucous components, and then distributed over the surface of the eye. In people with dry eye, this tear film dries very quickly-about 5 seconds as opposed to 20 seconds normally.

“Dry eye is one of the most common eye problems, particularly in Australia. Globally about one in five suffers from it,” says Sophia Tragoulias , who undertook research into the problem at the Vision Cooperative Research Centre in Sydney, and is now working for Parexel International. “To solve the problem, we need to able to produce a good tear film.”

By comparing the surface characteristics of complete tear films with those of the component compounds, Tragoulias was able to develop a more accurate picture of the structure of the film itself. She was able to show that the film actually consists of an outer oily layer containing several different types of proteins and mucous. Underneath this, in contact with the eye surface, is a second layer composed of the same components, but in different proportions.

“Current treatments for dry eye usually involve rewetting drops, which mostly add to the watery component of tears. But this can provide temporary relief, but it doesn’t help to produce a stable tear film to solve the problem. We believe, with our new knowledge of the structure of the tear film, we can potentially design better contact lenses, and tailor more effective drops to soothe dry eye.”

Although dry eye can occur at any age, it is estimated that nearly three quarters of people over 65 experience it. Dry eye is also a major problem for about three quarters of the people who wear contact lenses. More than half the people who discontinue using contact lenses give dryness and discomfort as the reason for doing so.


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