Intrigued, I decided to give the most affordable brand, Innoxa ($14), a try. They arrived this morning, so I popped them in. I took pictures of my eyes before and after the drops, so if you want to see if they really work, just keep reading.
When I put the drops in, I noticed that they're blue (the drops actually kind of dyed the skin under one of my eyes), which would explain the whitening claim; most people's eyes have yellow or red in their whites, so blue would counteract that to make your eyes look whiter and brighter. The drops also made my eyes extremely watery. That might explain the sparkle, and it definitely explains the stuffy nose I got after using them.
I can't really see much of a difference in vividness, at least no more than after you've been crying or used regular eye drops, but maybe there is one. Check it out for yourself: