I am scheduled for cataract surgery later this week.  My doctor prescribed and gave instructions for me to use Acuvail (drops) twice daily and Zymar 4 times daily, for three days before surgery and afterward.  When I picked up the prescriptions, he had changed the Acuvail to Nevanac 3 times daily. What is the difference between Acuvail and Nevanac, and why might he have changed the prescription?  I believe both are NSAIDs.