According to new research, the optimum eyelash length is one third of the width of the eye.
Studying samples found in the American Museum of Natural History in New York, David Lu and colleagues from the Georgia Institute of Technology found that 22 species of mammal had the magic ratio of eyelash to eye length.
The group used a purpose built mini wind tunnel to test the aerodynamic properties of different models of lash lengths, finding that the lashes redirect the flow of air.
Shorter eyelashes did not stop the flow of air, creating a ‘stagnation zone’ above the eye’s surface. While longer lashes direct the flow of air to the ocular surface, increasing evaporation, and increasing the likelihood of the eye drying out.
The authors suggest that the optimum length minimises dust particles and evaporation of the eye surface. They suggest that “eyelash-inspired protection” could be used to protect optical sensors.
The research is published in the Journal of the Royal Society Interface.
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