I have a 9 week old pullet that I noticed this morning is keeping her right eye closed. I can open it and if I pick her up she opens it, but once she calms down she closes it again. Checked her over, no lice, mites, no worms in poo(or blood). She is eating and drinking. She is walking but I have not seen her try to fly yet this morning. No discharge either. She just keeps it closed. I cannot tell when it is open if she is seeing out of it. I know once my hand or something comes into view of her left eye she reacts. What could it be, injury or illness. She and her 2 "sisters" were free ranging with the big kids yesterday for a couple of hours(these 3 are in the grow-out tractor working on integration into big flock) and she had both eyes open when I closed them in the tractor. It did get down to about 34 where I live, but they are on their last night of brooder light in the tractor(75W bulb, so keeps roost around 40-45). I am stumped on this one. It would be different if both eyes were closed and not just one. Someone please help me. Thanks