I’m not exactly sure how it works, but students at the Massachusetts Institute of Technology have created an image that seems like an optical illusion, but it’s really a vision test.
Look at the image above, or better yet, watch this video, from about a foot away on a typical computer screen. If you see Albert Einstein, your eyes are pretty good. If you see Marilyn Monroe, you need glasses. Kind of unbelievable, right? But it works. Check this out:
ASAP Science explains this phenomenon:
“Depending on how well you’re able to focus or pick up contrast, your eye will only pick out details. Up close, we’re generally able to pick up fine details like Einstein’s moustache and wrinkles. But as the distance increases, or if your vision is poor and creates a more blurred image in the first place, your ability to pick up details fades away.”
This isn’t a completely reliable test — you should still probably go see an optometrist or an ophthalmologist to take care of your eyesight. But it’s better than nothing!