All surgery has some risk, but the risks involved with PECG are minimal. The largest risk is that the pterygium returns. The rate of recurrence of the pterygium with the PECG technique is about 5%. (The risk of recurrence if an autograft is not used is about 50%.)
Another risk is that the graft does not stay in place after the surgery. This is uncommon (less than 1% risk.) If the graft does not stay in place, then there is a greater chance that the pterygium can return. Other rare risks include eye infections, and changes in vision.
