Yes, we've got glasses with a UK prescription in Wal-Mart (good service, they arrive within a week) and they are much cheaper than in the UK. If you have any problems with them when you come home, Asda will fix them for you if you tell them you bought them in Wal-Mart.

You can also get them in places like J C Penney (http://www.jcpenney.com

You can even buy them online from http://www.eyeglass.com/ with shipping to the UK if you know your prescription!

Oh, I almost forgot... one tip is not to look for photochomic sunglasses (non-prescription) as they cost a fortune in Florida (like $150 upwards!) and you can buy them for about £20 in Boots in the UK.