So his vision is normal because the visual areas are normal, his emotions are normal, he'll laugh, he'll cry, so on and so forth, but the wire from vision to emotions is cut and therefore he has this delusion that his mother is an impostor.
Su visión es normal porque las áreas visuales están normales, sus emociones son normales -ríe, llora, etc.- pero la conexión de la visión a las emociones está rota y por lo tanto sufre del delirio que su madre es una impostora.