Are you seeing double? Good. Before you head to the optometrist for the most comprehensive check-up your insurance will cover, remember, not everything is as it seems. Case in point? these ultra-confusing real-life photos that somehow make our brains break, leaving us questioning what, exactly we're seeing on the screen before us. 

From the mind-bending powers of yoga to a very evocative paper cut, here are 21 real-life optical illusions that will have you questioning your eyes.