WHILE WAITING AT A STOP LIGHT CONSUMER'S VEHICLE WAS REARENDED BY ANOTHER VEHICLE. THIS CAUSED THE DRIVER'S SEAT BACK TO COLLAPSE BACKWARDS, RESULTING IN LOSS OF VISIBILITY. THE VEHICLE WAS THEN PUSHED INTO ANOTHER VEHICLE. THE DRIVER'S HEAD HAD WENT THROUGH THE REAR WINDOW. VEHICLE AT REPAIR SHOP. DRIVER HAD EMERGENCY ROOM TREATMENT. *AK