@bluedolphin-- Have you guys spoken to an eye specialist?
I'm not a doctor but I don't think that a cornea transplant can be used for irregular astigmatism. Cornea transplants actually result in irregular and regular astigmatism for many people. I know someone who had the procedure and developed irregular astigmatism as a result. So using a cornea transplant for irregular astigmatism will possibly land the boy back where he started. Moreover, a donor has to be found for a cornea transplant and that's difficult as well.
Special glasses, and possibly laser treatment seem to be the best options right now. But I suggest speaking to an expert about this, or maybe even several, for the best advice.