Joni, I wondered about this and have asked many people who research in this
field. The eyes change shape and, to a tiny extent, size with different
emotions. A fine layer of water may cover the eye giving the twinkle
people talk about, or an eye may become dry causing the person to appear
Most sighted people learn to interpret these things without ever being taught. Even when I could see, I was but a partial, so never could see eyes all that well, hence my interest in understanding.
Even the way the eyelids are held is a powerful nonverbal communication. A fluttering of the lids may be a flirt by a woman, eyelids at half mast may be what are called bedroom eyes, meaning a seductive intent, very wide open eyes mean surprise or shock, and so forth.
It is fascinating stuff. The estimate is that 70% to 80% of all communication between humans is nonverbal. This would suggest that we miss out on a lot, but it turns out that we become experts at interpreting voices and perhaps, of feeling ferrimones in the air that suggest emotional states.