I think it's exaggerated somewhat, but in ways that make sense for the medium, like smoothed-over dialogue and the lack of regular potty breaks.

But, then, I spend a lot of my time looking at faces for cues (consciously so) in an effort to avoid foot-in-mouth disease. It doesn't feel *that* unreal to me: I notice a shift in the set of a face, and because the eyes are where I'm usually looking, I'll often think of it as something seen in someone's eyes, though the jaw and the lips and the cheeks were silent partners in the deal.

It's not only eyes darkening in text; they change color a lot too, and sometimes other characters can interpret the different colors. It's that, the interpretation, that really gives me pause.

I've had people swear this in real life, too. "My eyes do such and such at so an so a time." I'm not sure if I believe it. I do know that mine shift along the grey-blue-green range depending on the light, on if they're bloodshot, and on what my pupils are doing. So if I'm upset, and it's made me slightly teary, one could purple up my expressions by saying something along the lines of: "Her eyes glinted wet and turquoise with unspoken upset." and not have it be to much of an exaggeration.