The proportion of patients gaining 15 letters was 56.1 % versus 12.3 % ( P < 0.001 ) at week 24 , 55.3 % versus 30.1 % ( P < 0.001 ) at week 52 , and 49.1 % versus 23.3 % ( P < 0.001 ) at week 100 in the IAI 2Q4 + PRN and sham + IAI PRN groups , respectively .