You can eat a carrot to cure blindness (except from a cream pie). A pet can also eat a carrot to cure blindness. You can use a carrot as a treat for training an herbivorous pet such as a horse. Non-herbivorous pets also consider a carrot a treat if they are blind.
The use of carrots to cure blindness originates from the real life rumor that the vitamin A in carrots helps improve your vision, but snopes.com classifies it as a false legend.
Carrots are permafood.
"What is certain is that carrots and their eyesight enhancing properties were known to the Greeks and Romans, yet they declined to plant them on any notable scale, considering them to be an inferior vegetable.... Carotene is converted to Vitamin A by the body and A vitamins are great for your eyesight - the Greeks and Romans were right after all, they just didn't know why."
"Claim: Eating carrots results in improved vision. Status: False."