I found mike suffered show a sign of "crossed-eyes" when he was doing his homework or looking at something not far from him! The eye doctor told me that they may have trouble changing their focus when looking from the blackboard to their books, he suggest me to buy him a pair of bifocal eyeglasses, how can such a young kid need bifocals?

Really and truly, it's wired if you find some kids wearing bifocal eyeglasses in the street,but they have the effect to reduce the amount of eye strain during close work, and they will improve the kids vision for near view and distance vision.