Bilateral amblyopia can get better if you persevere and ask him to use his eyes as much as he likes but make sure that he is wearing and looking through appropriate glasses. Light should be adequate when he is reading or doing any close work. Book should be kept at best visible distance from eyes. Sometimes closing one eye at a time and using the other eye even for about an hour daily helps. More over try to find what has caused the condition in the first place so that other diagnosis does not get missed.