Carrots contain beta-Carotene (bet you can't guess the etymology.) Beta-Carotene gets metabolized into various forms of vitamin A, including retinal, which is necessary for eye health.
So, it's not that carrots can help you see in the dark; it's more that some eye diseases (which have initial symptoms including diminished night vision) can be prevented by eating carrots, just like some gum diseases can be prevented by eating oranges.
So, it's not that carrots can help you see in the dark; it's more that some eye diseases (which have initial symptoms including diminished night vision) can be prevented by eating carrots, just like some gum diseases can be prevented by eating oranges.