[just another ref]

I personally have always thought that this would get called a foul more often except for the fact that it is so difficult to see. There is little if any reason to look at any players face, therefore so often all we see is the offended player grab at his own eye after the fact. It could have been a bug or an eyelash, but usually it is obvious, after the fact, what happened.

4-19-1: .....contact which hinders an opponent from performing.........

One is hindered from doing most things if one cannot see.