go to to here http://au.answers.yahoo.com/question/index;_ylt=Al5dNgzM5Rn742QxxRBdAGnh5gt.;_ylv=3?qid=20081121071549AAHBc40&show=7#profile-info-PpqsB1THaa go to the question i answered.vitamin is not all the factor, but it is a factor lacking in it will cause problems, and serious lack will cause vision problems,but taking vitamin often will not harm you and even improve your overall health, but don't take to much vitamin A, or anything that cause is toxic affect when overdose, read the label and search up all the ingredient. but habit in our major cause in western country, kale, or spinach, bilberry, (lutein 6mg - 20mg) eat a lot of fruit and vegetable, stop eating rubbish, http://health.nutralife.co.nz/Product.aspx?id=1076 here's the websites - http://www.cleareyesight.infoor if you want to spend money use eyerelax, eyepower from japan, eye exercise device from china or accommotrac - http://www.accommotrac.com/ - http://www.roffereyecare.com/http://www.eyecollege.com/http://www.central-fixation.comhttp://web.singnet.com.sg/~hanwen/nvifaq.htmgood luck and wish all the best