This is because pumpkin contains a nutrient called beta - carotene, which a form of vitamin A that helps improve eyesight and the health of skin cells. (yurielkaim.com)
Sweet potatoes contain high levels of Vitamins A and Beta - carotene, a powerful anti-oxidant which aids in improving eyesight. (lovingpetsproducts.com)
When researching these methods of improving eyesight naturally, I found the books The Bates Method for Better Eyesight Without Glasses and Relearning to See helpful. (wellnessmama.com)