It makes me mad that a doctor would recommend that you get eyeglasses for a 4 year-old with 20/40 vision. My apologies to people who have followed that advice and I mean no disrespect, but there is no way I would follow that recommendation. Many children have 20/40 vision at that age. Your daughter's eyes are still developing and I would bet that she can see really well. I thought the article below was pretty informative about the eye exam industry. Also, if you can get a hold of the book, "How to Raise a Healthy Child in Spite of Your Doctor," by Robert Mendelsohn, (it should be in any library) he has a whole chapter on pediatric eye exams, etc. called, "Protecting your Child's Vision." Best of luck!
http://www.smartmoney.com/spending/d...ell-you-11382/