Eyelashes protect the eye by catching dust and triggering a blink when touched.

The longer version

Eyelashes act as a first line of defence for the eye. Their length and spacing let them intercept dust, sand and small flying particles before those reach the delicate surface, and they also reduce airflow directly across the eye, slowing evaporation of the tear film.

Each follicle is richly supplied with nerve endings, so the lightest touch triggers a blink through a fast reflex arc. The blink sweeps the lash line clean and closes the eye for a moment. Their curve directs most stray material away from the eyeball rather than toward it. Like other body hair, lashes follow a growth cycle, so individual hairs are shed and replaced over time.

Where this entry sits

These facts look at how the human body works in ordinary moments, from breathing and blinking to balance and sleep. They focus on anatomy, senses, and small reactions that happen constantly without any conscious effort. The full list sits on the Human Body page, where every entry is listed in order.