A new study suggests that there’s much more to eyelashes than meets the eye
It turns out eyelashes are much more than just fine hair at the end of out eyelids. According to a new study by two Georgia academics, a good set of lashes will reduce evaporation from the eye by up to 50%.
The study was published in Tuesday’s edition of the Journal of the Royal Society Interface. The research discovered that the right size eyelash will also cut 50% of the airborne particles that land on the surface of the eye.
That likely explains why people without eyelashes typically suffer more eye infections than those who do, notes study co-author David Hu, a professor at the Georgia Institute of Technology.
“People think eyelashes are cute,” Hu commented. “But they’re actually protecting us from a lot of extra illness.”
Hu became fascinated with eyelashes after the birth of his first child. Amazed at his daughter’s tiny, perfect lashes, he wondered about the purpose of lashes and what other animals also have them..
One-third eye width is “golden ratio”
In an interesting finding, the research discovered that in both human and other mammals, eyelashes are always around one-third as long as the width of the eyes. To determine why, the team created an artificial “eye” out of a water-filled dish and a ring of plastic mesh that simulated lashes. A small fan provided airflow over the “eye”. The researchers the calculated how much water evaporated and how many particles blown by the fan landed on the “eye’s” surface.
The results confirmed the utility of the “golden ratio” as both evaporation and dust and pollen particles onto the surface of the eye were the lowest when lash length was around one-third of eye width.
The researchers then developed computer models that showed that short lashes do help to divert some air away from the eye’s surface. Moreover, longer lashes kept even more air away, but not above a certain length. It turned out that eyelashes that are greater than one-third eye width actually direct more air toward the eye.
Possible applications in technology
The research offers strong support for the authors’ beliefs about the adaptive value and function of eyelashes, noted University of Delaware mathematician Richard Braun, who studies the films made by tears, in an email to National Geographic. He also said he agrees with the researcher’s hypothesis that eyelash-like filaments could be an effective method for keeping dust off large objects which need to remain clean such as solar panels.