I've been wondering about how often kids should have eye exams. My son, who's 6, hasn't had one since he was a toddler, and I'm starting to think we might be overdue. A friend of mine told me her daughter had an eye exam at 4, and they found out she needed glasses, even though she didn't show any signs of having vision problems. That made me think maybe I should get my son checked, just to be safe. But is once every few years enough at this age, or should it be more frequent?