Forget going to the eye doctor (or opthamologist) to find out whether you need glasses, ASAP Science has devised a way to figure it out in a few seconds by looking at this GIF!
Do you see Marilyn Monroe or Albert Einstein?
You should see both. If you never see Einstein, chances are you need glasses.
The reason the image appears to transform is because Einstein's image is made up of super dense pixels, making his details stand out while the other image is made up of far fewer pixels, causing only Marilyn's basic features to show up. Freaky!
ps: If you already wear glasses, try taking them off and then see the gif.