Vitamin A is responsible for good eyesight. It is the first fat-soluble vitamin. It plays an important role in the functions of the retina of the eye. Retinol is a kind of preformed vitamin A which usually occurs only in animal foods. However, carotenoids in fruits and vegetables can provide vitamin A too. I think you can get enough vitamin A through food rather than buy some vitamin pills in the stores.
I'd like to tell you a story. Once upon a time, there was a boy who didn't want to eat carrots. His father told him that carrots which are rich in vitamin A are good for his eyes. But he didn't believe that so the father quip," You've never seen a rabbit wearing glasses, have you?" Though that is not the real reason, but the carrots which are rich in vitamin A is best known for its role in maintaining good vision. There are four types of photopigments in human retina. It is a place to store vitamin A compounds. They can help us to see things clearly especially when we are in the dark room. You can buy vitamin pills in any chemist's shops. It is recommended that daily allowances for Vitamin A range from 700 mcg for women to 900 mcg for men. As for children, it is 300 mcg for ages 1-3 years, 400 mcg for ages 4-8 years, and 600 mcg for ages 9-13.