Science classes can teach you about an awful lot, from why dogs look like wolves to the nature of reality, but it always seems to avoid getting to the bottom of one burning question: what the hell is that tiny hole on the bottom of your eyelid?
Well, first things first, this fleshy little pinprick is completely normal. Some people's are larger and more obvious than others. However, if you go up close to a mirror, most people should be able to see a small almond-shaped hole around 2 millimeters away from the inner corner of each lower eyelid. This is scientifically known as your lacrimal punctum.
Despite misconceptions and know-it-alls on Yahoo Answers, the hole does not produce tears, although it is part of your eye’s guttering and drainage system. It’s also the reason why you get the sniffles after you cry. Knowledge is power.
As mentioned, it doesn’t produce the tears themselves. That job is, of course, given to the tear duct. The hole’s task is to drain these tears. It’s a bit like the opening of a canal that connects the eye to the lacrimal sac. From that sac, the tears drain through the lacrimal duct into the nose, hence why you get a runny nose after you shed a few tears or why you can sometimes taste eye drops at the back of your throat.
This next part is not for the faint-hearted.
There’s a medical procedure that involves placing tiny cylinder-shaped plugs into these holes in order to stop dry eyes. This helps to stop the eye from draining so much fluid out, keeping it moist, healthy and better at fending off infections.
Equally squeamishly, the drainage system of the lacrimal punctum can sometimes backfire and reverse the flow. That means that it has been known for tears, discharge, air, and even blood to squirt out of these holes. It's also how some people pull off the rather gross "party trick" of squirting milk out of their eyes.
In fact, a Turkish guy called lker Yilmaz holds a world record for squirting milk from his eye a distance of 279.5 centimeters (9 feet 2 inches). Seriously though, don't try this at home, it's a sure-fire way to give yourself a nasty eye infection.
See, who would have thought a tiny hole in your eye could so interesting?