is in darkness ... walketh - “is” marks his continuing STATE: he has never come out of “the darkness” (so Greek); “walketh” marks his OUTWARD WALK and acts.
whither - Greek, “where”; including not only the destination to which, but the way whereby.
hath blinded - rather, as Greek aorist, “blinded” of old. Darkness not only surrounds, but blinds him, and that a blindness of long standing.