Blindness

When i first read that the theif went blind I thought it was good karma because how dare you! That was the guilt of his wrongdoing putting shame on him. I feel like i could picture his panicking from the text. When I  his scene of him going blind it seemed to me that since he came in contact with the old blind guy he helped home, he gained blindness but the other part of me was saying like blindness cannot be contagious so i was confused but then i read on in the chapter...