why eating carrots is important for good vision?

Eating carrots will only help your vision if you're deficient in Vitamin A. However, most people in developed countries have sufficient Vitamin A and their eyes won't benefit no matter how many carrots they eat.

http://www.snopes.com/food/ingredient/carrots.asp

http://healthlibrary.epnet.com/GetContent.aspx?token=0d429707-b7e1-4147-9947-abca6797a602&chunkiid=156972

http://www.webmd.com/diet/carrots-good-for-eyes