As you say NIrish Guy, many do not seem to wear glasses. I used to take one of my friends to the dentist on my annual visit. One time he asked if he could get new glasses instead of going to the dentist. I took him to the Beauty Glasses across from Boys Town on Second Rd.
He chose white frames, that seems a bit much for me but he liked them so he was happy to replace his scratched glasses. While many do not seems to have glasses i suspect many have glasses but don't wear them as they are old, or scratched and just don't want to spend the baht to get new ones. As an aside, I also made sure my friend went to the dentist's office while I was there in Pattaya.