Tommy Edison (previously) routinely makes videos to answer questions about what it's like to be blind. Some things he doesn't know, because he hasn't experienced them, like vision. Christine Ha (previously), on the other hand, went blind later in life. Here they discuss their experiences.
There's a big difference between the two. Once you know what sight is like, you can miss it terribly. But you can remember it, too. Also notice the difference in how they use their eyes. Edison keeps his shut just about all the time, while Ha is very aware of what she looks like on camera and what it means to follow someone's eye gaze, even when you know it's not working. -via Laughing Squid