Do you know that you blink 10-20 times a minute? Every time it happens, your eyes get a few milliseconds of protection and quick moisture bath. Blinking also washes away the mucus your eyes make all day long.

When you're asleep, you don’t blink that gunk away. It collects in the corner of your eye closest to your nose -- where your lashes meet your eyelid. The proper name for it is rheum, but you probably call it sleep.

You might spot cream-colored mucus from time to time. That's also normal. It forms when an irritant, like sand or dirt, gets in your eye.

But eye discharge can signal something you can’t blink or wipe away.

Pinkeye. Your eyelid is lined with a see-through membrane called the conjunctiva. It also covers the white part of your eyeball. This layer is full of tiny blood vessels you normally can't see. When they get infected, the whites of your eyes look red or pink, hence the name pinkeye. Your doctor could also call it conjunctivitis.

It’s caused by allergies or a viral or bacterial infection. Eye discharge is a common symptom. Babies can get it if a tear duct hasn't opened all the way.

Blocked tear duct. You have a tear gland above each eyeball. They make the fluid that gets wiped across your eye when you blink. It drains into ducts in the corner of your eye closest to your nose. If a tear exit duct is blocked, that fluid has nowhere to go. The duct can get infected and cause discharge.

Dry eye. Tears are made up of four things: water, oils, mucus, and antibodies. If their balance is off, or if your tear glands stop making tears, your eyes get dry. When your eye doesn't get enough fluid, it tells your nervous system to send some. That sometimes comes in the form of emergency tears, which don't have the same nourishing balance as regular tears. Emergency tears with too much mucus can lead to strings of gunk in or around your eye.

Corneal ulcer. The cornea covers your iris, the colored section of your eye, and your pupil, which lets the light in. It’s rare, but an ulcer could happen when there's an eye infection or extreme case of dry eye. It can create discharge.