A pterygium may not cause problems other than redness and eye irritation however, if it continues to grow onto your cornea, it may cause vision problems.
Therefore, failure to have the treatment performed when recommended by an experienced Pterygium Ophthalmologist can increase the risk of long term damage to your vision.
Removal of recurrent pterygium usually performed by another surgeon increases the risk of persistent double vision. This could require further surgery to correct the situation.