Optical illusions that play on viewers' eye-brain co-ordination, have been taking the world by storm.
Here is a set of puzzles/illusions that have been designed to test the sharpness of your eyesight and quick-thinking skills.
Some of them have been created by the geniuses at playbuzz.com, who say "only the keenest eyes can pass" these tests.
So, what are you waiting for? Give it a go! Put yourself to the test and let us know (honestly!) how many you were able to crack.