After extensive research, a team of scientists from the Georgia Institute of Technology has discovered that 22 species of mammals, humans included, have eyelashes that are one third the width of their eye. This helps keep the eyes protected from dust and other things that could affect them.
According to the study, this is the perfect length of the eyelashes, and anything longer or shorter than this length allows airflow around the eyes, which causes dust to touch the eye surface.
Guillermo Amador, researcher at the George W. Woodruff school of mechanical engineering and one of the scientists involved in the study, explained that the role of the eyelashes is to form a barrier that controls the airflow and the evaporation rate on the corneal surface.
Professor Amador added that when the eyelashes are short or longer than the one third ratio, the effect on the air flow is diminished. If the eyelash is longer than the one third ratio, it funnels air and particles of dust into the eye.
Amador and his team of researchers went to the New York American Museum of Natural History in order to measure the eyelashes and the eyes of various species of mammals.
Except for the elephant, which has a pair of very long eyelashes, all the other studied species had the same ratio of lash length to their eye width.
The researchers then created a wind runnel to simulate the flow of air that comes in contact with the human eye.
The experiment suggested that when short lashes grow longer they reduce the air flow, which creates a layer of slow-moving currents of air above the cornea, keeping the eyeball moist for a longer period of time, and also kept dust particles away.
The experiment revealed that the air current hit the eyelashes and was directed away from the eye.
The authors of the study stated that long, fake eyelashes, even though they may look good, cannot really protect the eye from harmful particles.
The researchers detailed the findings of their new study in the Journal of the Royal Society of Interface.
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