The Science of Eye Crust

What is that crust in the corner of your eyes in the morning and why

does it show up overnight? The medical term is rheum. It is basically

leftovers from the eye's cleaning system. Your eyes constantly make tears, mucus,

and oils to keep the surface smooth and trap dust. During the day,

blinking spreads tears and drains debris through the tear ducts. While you sleep,

you blink far less so that material can collect and dry at the corners.

What is in it? A mix of dried tears, mucus,

skin cells, oils, and trapped dust. Amount varies. Dry air,