***** NOT A TEACHER *****
Hello, EnglishHobby:
I was wondering whether you have had a chance to check Mr. Michael Swan's very popular Practical English Usage.
Mr. Swan says this:
"Big and large are used mostly with concrete nouns -- the names of things you can see, touch, etc. Big is most common in an informal style."
He then gives these two examples:
"Get your big feet off my flowers."
"I'm afraid my daughter has rather large feet."
An ophthalmologist (eye doctor) talking with Mr. Smith would probably say, "I notice that your wife has large eyes, so I have decided to ...."
Surely, she would never say, "Wow! Your wife has big eyes!" (That's my opinion, at least.)
*****
When I was a child (a million years ago), my teacher would scare me when she read a story entitled "Little Red Riding Hood."
Little Red Riding Hood was a girl who decided to visit her grandmother in the forest.
She did not know that a wolf had done something bad to her grandmother. Then the wolf put on her grandmother's clothes.
When Little Red Riding Hood arrived, she saw her grandmother (who was really the wolf). She said, "Grandmother, what big eyes you have!"