Carrots are rich in beta-carotene, a carotenoid pigment found in many orange fruits and vegetables. Beta-carotene is an important precursor for vitamin A. An extreme lack of vitamin A can cause blindness. In fact, in the developing world, vitamin A deficiency is the leading cause of blindness [source: Web MD].
Lack of vitamin A can also lead to xerophthalmia, a condition in which the eyes can no longer produce tears, dryness in the eyes, swollen eyelids and corneal ulcers. Vitamin A can prevent the formation of cataracts and macular degeneration, the world's leading cause of blindness [source: All About Vision]. However, if your vision problems aren't related to vitamin A, your vision won't change no matter how many carrots you eat.
Carrots aren't the only vegetable that contain the essential beta-carotene that can help your eyes. Other orange-colored foods, such as sweet potatoes, mango, pumpkins, apricots and cantaloupe, are also sources of beta-carotene. This nutrient can also be found in dairy products like milk and cheese as well as egg yolks and liver.
But watch how much beta-carotene-rich fruits and veggies you eat. Since beta-carotene is a pigment, your skin might become orange. Although this likely is harmless, if it happens to you, you might want to consult a health care professional to make sure you're consuming a balanced diet.
In addition to beta-carotene, carrots also contain lutein, an antioxidant. Foods rich in lutein have been found to increase pigment density in the macula, the oval-shaped yellow area near the retina of the eye. The greater the pigment density in the macula, the better protected your retina is and the lower your risk for macular degeneration. In addition to carrots, spinach, kale, Swiss card and dark, leafy greens also contain lutein.