Sorry for the late update
Mexi is doing great. The vet, thank doG, didn't have to make an incision in her eye. The thorn pulled right out. He sent it home in a vial for me, and I have some pictures to post so you guys can see how big it was (my camera is dead right now, so have to wait for it to charge). I felt so bad, it had to hurt like a mother, especially having in it her eye for as long as she did.
I have to put drops in her eye for a couple of weeks, but I don't think there is going to be any lasting damage. The cloudy spot in her eye where the thorn was is already clearning up.
Thank you guys for the positive thoughts!
She came out friendly with the kennel guy, too, so I felt much better leaving her there. Mexi doesn't like many people, so I was impressed that she liked him!
Love me, Love my dogs.