The median preoperative scleral thickness was similar in all 3 groups : AMT = 0.45 mm , LST = 0.48 mm , and LCT = 0.52 mm ( P = 0.257 ) ; however , 6 months after surgery , the median thickness in the AMT group ( 0.19 ) was significantly less than that of the LCT group ( 0.57 ) ( P = 0.27 ) or the LST group ( 0.76 ) ( P = 0.19 ) .