A recent study on the eye finds that the optimal eyelash length is one-third the width of the eye for humans, as well as 21 other mammals.
Georgia Institute of Technology researchers put together a wind tunnel about 2 feet tall with a makeshift eye. The wind tunnel was meant to recreate airflows equivalent to those that would affect a human, adult eye. A 4-millimeeter deep, 20-millimeter diameter aluminum dish acted as the cornea. Mesh surrounded this dish in order to replicate eyelashes.
The team was able to determine the optimal eyelash length that helps prevent certain levels of airflow around the eye, which in turn leads to less dust hitting its surface.
Eyelashes actually form a kind of barrier around the eye that controls this airflow and the rate of evaporation on the surface of the cornea. The researchers found that if the lashes were too short or too long they weren’t as effective at doing their job. When shorter lashes grew longer they reduced airflow, creating a layer of slow-moving air above the cornea keeping particles away. When eyelashes were too long it lead to faster evaporation.
The results of this study could potentially lead to eyelash inspired filaments to protect solar panels, photographic sensors or autonomous robots in certain atmospheres.