Some well-placed eyeliner can make a look. It can make someone look entirely different with the right application. But Julie Beck from The Atlantic highlights a small study that says those countless beauty videos you've been watching on YouTube may have been giving out bad advice that's counter to what health experts would suggest.

Most beauty experts will tell you to get as close to your eye's “waterline” or on the lash line. The study, published in the journal Eye and Contact Lens Science and Clinical Practice, recommends putting on that eyeliner as far away from the waterline as possible, otherwise you might as well be drawing it on your cornea.

The study consisted of researchers drawing glitter eyeliner “on the lash line” on three female participants to track the movement of the eyeliner particles (hence the glitter). The participants' eyes were filmed to see how many glitter particles wound up in the tear film (the outer layer of the eye).

Alison Ng, from the Centre for Contact Lens Research at Waterloo who led the study, noted in a press release that "the makeup migration happened quicker and was greater when eyeliner was put on the inner lid margin."

There were 15 to 30 percent more particles in the participants' eyes. But after two hours, their eyes were able to filter out the glitter particles, so contamination is temporary. Still, the researchers concluded that “it would be beneficial to advise patients to reserve the application of eyeliner pencils to anterior to the lash line.”

However, Ng had a special message for contact lens wearers:

"People who wear contact lenses are most likely to notice some problems. If they have eyeliner stuck to their lenses, increasing deposits might cause vision disruption as the lens becomes cloudier."

You may not realize it (I sure didn't), but eyeliners are harborers of bacteria. Ng recommends that before each application you should “thoroughly sharpen your pencil eyeliner before each application and get rid of the stuff that's stuck to the end.” Even with twist-up eyeliners, you should “cut some off the end before each use. And always make sure to fully remove eye makeup before bed."

This study echoes other recent research about concerns over other eye-related makeup, particularly mascara. Researchers claim you shouldn't play with your lash length — they're the size nature intended them to be. Indeed, the eye is such an essential part of our lives, allowing us to see and take in information; it would be a shame to damage it for the sake of beauty.

Geoff Jones, a professor of Business History at Harvard Business School, talked about how the idea of beauty has become quite homogenized in recent times. Before TV and movies, the beauty industry in different countries had their own ideas on the subject. For example, white faces and blackened teeth were considered the epitome of female beauty in early 19th Japan. So, define your own beauty: