I have different body language, some of which includes the eyes. I've noticed my eyebrows, and how big my eyes are change. Also, one part just stares in her lap or scrunches her eyes tight because she's scared of eye contact, while another glares right at the person they are talking to because she's more defiant. it is interesting that you've noticed. Do you know why the difference? It migth help you learn more about them, what they find safe, what they are stressed about. If there is something on a shelf that one likes or a picture on the wall, etc, that might give you some clues as to their interests, to help build trust and communication between you.

Not sure if that's what you're looking for, but it interested me!
IJ