Laser treatment was found to reduce the IOP fluctuation during the daytime.IOP fluctuation decreased from ( 3.6 1.0 ) mmHg to ( 2.3 1.0 ) mmHg in the standard-energy group , and decreased from ( 3.9 1.4 ) mmHg to ( 2.4 0.9 ) mmHg in the sub-threshold energy group , which was significant different ( t = 4.911 , 4.679 ; P < 0.05 ) .