Hi BrainStuff, Cristen here.
Today’s question is “What are eye boogers?”
If you’ve ever had to wipe gunk out of the
corners of your eyes, it’s not because you
were visited by the Sandman or a magical mucus
fairy.
Nope!
We live in a cruelly mundane universe.
I’m sorry if I’m the first to break it
to you.
Eye boogers are a buildup of the “precorneal”
or “basal” tear film that coats and protects
your eyes -- plus any foreign particles it
catches.
This tear film is just 3 micrometers thick,
which is less than half the diameter of a
red blood cell, but it’s made up of 3 components:
the mucin, the aqueous, and the lipid.
The aqueous component is the operative one:
It nourishes, lubricates, and flushes your
eyes’ cells.
It also smoothes over the microscopic lumps
and bumps on the surface of your eyes, creating
a smooth lens that optimizes light transfer
into your retina.
The other two components are a support system
for the aqueous one: The mucin component underneath
allows it to temporarily stick to your eyes.
Mucins are the proteins that make mucus slimy.
And the lipid component outside holds it in
place, so that you’re not just crying constantly
like you’ve got Moulin Rouge playing on
loop.
Without the lipid layer, our tear film would
drip right off of our eyeballs.
But how do these components become eye boogers,
and why do they accumulate in the inner corners
of your eyes?
I’ll tell ya.
When you blink, your entire eyelid doesn’t
close simultaneously.
It shuts like a meaty clapperboard, from the
outer corners of your eyes inward toward your
nose.
Your tear film gets pushed along by the motion.
Upon reaching the inner corner of your eye,
most of the film drains out through the tear
ducts, which empty into your nasal cavity.
But some of the film – the mucins, oils,
and debris – can clump together and get
stuck.
When enough of that builds up, it forms the
goop known as eye boogers.
And when it accumulates and dries overnight
because you’re not blinking it away, it
forms the crusty gunk known as sleep or sand.
Isn't this the sexiest science you've ever
heard?
So that answers today’s question, but I’ve
got a question for you: What other gross stuff
do you want to know about?
Let us know in the comments.
And to learn more about everything from tears
to space telescopes, head over to HowStuffWorks.com.
