Many people believe that eating carrots helps you to see better at night, and this idea comes in part from Cunningham's wartime reputation as a night fighter pilot - which was popularly attributed to his eating carrots. Here's the real story:
The eye's retina detects light via rods and cones. The cones detect detail and colour, but need plenty of light to function (like a 'slow' film emulsion). The rods have low acuity and can't distinguish colour at all but need less light (like a 'fast' emulsion) so are used for night vision.
The rods work by virtue of something called rhodopsin (visual purple), an ingredient of which is vitamin A. Therefore a deficiency of vitamin A can lead to night blindness, and night blindness caused in this way can be treated with supplements or foods rich in Vitamin A (carotene) - this includes carrots, but also (better) apricots, dark-leaved vegetables such as spinach, and bilberries.
However, this is about correcting defective night vision by correcting a vitamin deficiency; there is no basis for believing that you can enhance night vision beyond normal levels by taking an overdose of carotene - any more than you can put more petrol in an already full tank. Excessive amounts of carotene can cause the skin to turn orange, though.