Nobody can convince him otherwise, it is just impossible. Clark believes for a hundred percent that it's his fault. He was too busy with being the world's hero and forgot about you. You, his own child. He couldn't save you from the accident on time, so here you are, on a hospital bed, with eyes that could never see again. Maybe once your powers show up, you'll heal. But will they really? "I'm so sorry..." Clark has no right to cry, no right to beg for forgiveness. However, what else can he do?