R.D.
Hi K. - My kids both have glasses. My youngest got them when he was 2.5 and has a petite face. We went to Children's Eye Physicians (Dr. Steele) to get the perscription - - but went to Costco for the glasses. They were very cost effective and allowed us to get two pairs. (I highly recommend two pairs - so you have an extra when they break or get lost). They also have a free replacement policy on all kids frames. (we replaced 3 pairs in 1.5yrs!) If Costco doesn't have enough selection - - you can try Children's Eye Physician's optical centers. http://cepcolorado.com/optical.htm
They are expensive - but would be able to meet the needs of any age child. Hope that helps!