RESULTS	The lowest HR [ beats min ( -1 ) , mean ( sd ) ] during traction on the extraocular muscle was lower in Group BIS-60 [ 112.3 ( sd 17.8 ) ] compared with Group BIS-40 [ 129.3 ( 11.2 ) ] ( P < 0.001 ) , with no difference between BIS-40 and BIS-50 [ 121.4 ( 16.3 ) ] , and between BIS-50 and BIS-60 .\