@Ric****
is correct there is no such thing as a retirement visa. There are several things that people commonly refer to as one.
What you're talking about is getting a 90 day Non-Immigrant Type O visa based on being over 50. You'd meet the financial requirements and turn in the correct documentation, the application will go under consideration for 15 days (21 in chiang mai) and then you go back to get the 90 day Non-O inked into your passport. Then you wait 60 more days and go apply for a yearly extension of stay by turning in the same documentation and meeting the financial requirements again.