DS failed the eye exam at school a few months back and we have an appointment with a pediactric eye doctor in a few weeks. I've noticed he seems to always get blue, red, and green mixed up. He will say literally every other color and properly identify it except blue, green, and red. He is 4 so he should be able to identify the colors. I'm starting to get concerned. Does anyone have experience with being color blind? How did you know you were and what colors can't you see?