In group A ( n = 46 ) mean visual acuity changed from 0.50 to 0.58 ( p = 0.003 ) , and from 0.55 to 0.55 in group B ( n = 59 , p = 0.83 ) ; mean percent change was 22.3 % in group A and 3.5 % in group B ( p = 0.03 ) .