Why do we have eyelashes?
For grown-ups: the science
Eyelashes help protect your eyes from dust, tiny bits, and moving air.
Eyelashes provide a physical barrier that intercepts some particles, trigger the blink reflex when touched, and reduce airflow and evaporation near the eye surface. They do not block everything, so tears and blinking also help protect and clean the eyes.
What about...?
Ask your child's own question
Transcript
Look at the tiny hairs along the edge of your eyelids. Why do we have eyelashes?
Eyelashes catch some dust and tiny bits before they reach your eye. This helps keep the eye's surface cleaner.
When something brushes your lashes, your eyelids can blink quickly. A blink helps move the tiny thing away.
Lashes also help slow down moving air near your eyes. This can help your eyes stay moist and comfortable.
So, eyelashes are little helpers for your eyes. They catch bits, start blinks, and slow the air.