Eyelashes’ special features help fling water from the eyes

Next time you’re caught in the rain, thank your eyelashes for keeping your vision clear.

Experiments with human eyelashes and eyelash-mimicking fibers pinpoint several features that help fling water away from the eyes, researchers from the Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences report December 20 in Science Advances. 

The exterior of an eyelash, or cuticle, acts like a “micro-ratchet,” the researchers report. Water can flow easily from root to tip but not in the opposite direction, thanks to scales that overlap like shingles on a roof. When the scientists dipped loose eyelashes in water and pulled them out again, more force was required to move the eyelash when the water was working against the ratchet than when going with it. And by dripping water on loose eyelashes, the researchers showed that the hairs are hydrophobic, meaning that water beads up on them and tends to roll off.