Have You Ever Seen A Rabbit With Glasses?
Yes, the answer to every kid's question; "Why do I have to eat carrots? How do you know they'll make my eyes better?"
As a child, I had no reason to doubt that my parents were correct, but as I got older, doubt crept in.
First, the obvious: How could a rabbit wear glasses? The glasses would just fall off if you tried to put them on.
It was actually a rumor started during World War II by the British to cover up a newly developed system they invented for their fighter pilots: Airborne Interception Rader, also known as AI. British Intelligence didn't want the Germans to find out about the new technology so they created a rumor that all of their pilots increased their daily intake of carrots to improve their eyesight in the dark. They hoped that explanation would explain why the Brits had suddenly increased the number of German bombers they were shooting down.
Here's the full article with the scientific explanation also.