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Thursday, 26 February 2015


Have you ever noticed that tears flow out of your eyes at instances outside when you are really crying. In cold weather or in a chilly breeze or even when you yawn, tear drops flow out of your eyes. Its no magic!!! Science have got the answer...

Our eyes are constantly producing tears. Every time we blink, tears spread across the surface of the eye, moistening it and clearing out miniscule dust particles. Those tears then drain into the lacrimal canals, where they’re funneled into the nasal cavity — which explains why we suddenly get runny noses in the cold. But when it’s cold and windy at the same time, the cold dry air causes this tear film to evaporate faster, Amador said, thus forcing the eyes to produce more tears.

“Following our study, eyelashes will help minimize the amount of air reaching the eye surface, so if someone doesn’t have eyelashes or has very long eyelashes, they will experience more discomfort and their eyes will produce even more tears,” Amador told Medical Daily in an email. “I think eyelashes help to reduce the amount of fluid our eyes have to produce to keep our eyes moist.

"For the study, the researchers first examined the eyes and eyelashes of 22 mammalian species at the museum, including hedgehogs and giraffes. Then, they built a wind tunnel to recreate airflow on an imitation human eye, made of a 4-millimeter deep, 20-millimeter diameter aluminum dish serving as the cornea; an acrylic plate to mimic a face, and mesh to replicate eyelashes. Their intention was to see how varying the length of the mesh would affect airflow on the cornea.

"As short lashes grew longer, they reduced airflow, creating a layer of slow-moving air above the cornea,” said lead author David Hu, an assistant professor at the university, in the press release. “This kept the eye moist for a longer time and kept particles away. The majority of air essentially hit the eyelashes and rolled away from the eye.” Once they went over the one-third ratio, however, they channeled the air directly to the eye.

The researchers said the findings could help people considering fake eyelashes, as they may affect eye health if they’re too long. Other uses could include everything from eyelash-inspired filaments to protect solar panels, photographic sensors, or robots in dusty environments. Or, we could just use the findings as a confirmation of why some people cry more than others when it’s cold and windy.

Culled From Medical Daily.