Is it abnormal for puppies not to open their eyes by 16 days old?

no not in my opinion. they don't just "boing"open one day;) youll see them opening a little first.what kid do u have if i may ask?

Answer

Puppies will ususally open their eyes arount 10 - 12 day's old.If they are not open yet, call or visit your vet.

Answer

puppies can take up to three weeks to open their eyes.

It depends on the breed of dog also, some breeds of puppies open their eyes sooner than others while others take longer.