Schools used to perform vision and hearing screening, possibly they no longer do, or not in your area. Schools also used to require a signed form following an annual exam with the child's pediatrician or family doctor (during which vision and hearing screening was ostensibly conducted, with referrals to specialists if needed).
A standard hearing test (done either by the school or ped) will not necessarily pick up APD. A kid might hear perfectly well, but can still have APD. I gather the same is true with certain vision problems; they won't be picked up with standard screenings.
