When people hear the term 20/20, they generally imagine perfect vision—but that's not quite the case. Having 20/20 vision means that you can stand twenty feet from one of those iconic eye charts topped with the big E and successfully read the fourth line from the bottom without the aid of contacts or glasses. And while we aren't suggesting that this isn't a pretty significant feat—what it means is that you have amazingly normal vision.
Ever wonder what you’re supposed to put in the “PD” box when you’re entering your prescription online? Pupillary distance (PD) is the distance between the centers of the pupils of your eyes, and it’s used to determine the proper lens shape and alignment of your prescription to your line of vision.