When describing discourse between two characters, don’t focus on the movement of their eyes. It is lazy and becomes redundant when they are glaring, rolling, squinting or blinking at each other. I don’t care. If their eyes physically pop out – that would be good to include. Imagine the surprise if they remove their left eye, pull a hair off it, spit, wipe it on their sleeve and stick it back in. Definitely distracting! Otherwise, keep the action to bodily movements.
My dad is a child of the 60s. We can be on the phone or in person when something we say will jog a song lyric in his head and he will start singing – randomly. Sometimes he sways. That’s unique and diverting. Bouncing back and forth between dialogue without any hint as to what your character is doing or thinking in between isn’t.
As they speak, narrate their hands moving. Do they pace with some nervous habit to show frustration? Biting nails, grabbing hair or counting to cool a temper? What about reaching over to place a hand on their companions’ shoulder for support or nurturing? Watch people as they converse. I promise you no one talks standing still. I don’t! Heck, I use hand movements talking on the phone. I pace, I move my neck around to stretch or reach for coffee to drink. Heck, I took a friend on a tour of my house using Skype (not sure she enjoyed it however). People move and describing that takes your writing from one dimensional to something real. Now you are recording life. Go a step further, you are creating life.