The laser used for PRK and LASIK is the same and both can treat even high amounts of astigmatism. The only difference is the amount of healing time between the two.
The laser that is used to treat your nearsightedness or farsightedness is the same laser that treats your astigmatism, whether you have PRK or LASIK. There are maximum amounts of nearsightedness, farsightedness, and astigmatism that the FDA has approved these laser for, but assuming you fall within the range, you should have no problem have your astigmatism treated during your PRK procedure. Thanks, Dr. Kang