The man with sparkling eyes who made the sweets.
While wide eyed in anticipation...
Both these clauses use a causative form of a verb to describe a person's eyes.
In English when we use caustive to describe a person's expression it means that they deliberately made that expression. Whereas these sentences sound like the expressions are natural/spontaneous.
1) Would these sentences be wrong if I just used the plain form of the verb? If not how would the nuance change?
2) Is there a way to know when I should use causative for something like this? It's not at all intuitive to me.
3) What other things can be described by this structure? Is it limited to eyes, facial expressions, any body gesture, an even wider scope?