In group 1 , IOP was reduced from a mean preoperative value of 29.7 7.7 mm Hg ( n = 3.5 glaucoma medications ) to a mean postoperative value of 21.3 6.7 mm Hg ( n = 3.5 glaucoma medications ) and 20.1 6.7 mm Hg ( n = 3.2 glaucoma medications ) at 6 and 12 months , respectively .