Alot of things could factor in. Environmental allergies, food allergies, genetics, etc. What food are you feeding? I know when Jackson ate a certain brand of food, his eye boogers were REALLY bad. He is now eating a grain-free food (Acana, as well as Go! Natural) and most mornings his eyes are totally clear. Sometimes, when the pollen count is high, he will have more, but since switching foods, it's sooo much better.
