AIM:To observe the effect of krypton laser peripheral iridoplasty(LPI) for acute attack of primary angle-closure glaucoma(PACG).METHODS:Eighty-five patients 85 eyes diagnosed with the acute attack of PACG were prescribed the base treatment.One hour later,they were randomized into two groups:the LPI group 45 eyes with IOP still above or equal 40 mmHg and the medical treatment group 40 eyes with IOP below 40mmHg.Symptoms,visual acuity,corneal clarity,the depth and flare of the anterior chamber,IOP were observed before treatment and 30,60,120 minutes,24 hours after treatment.And the time used to lower IOP to 21 mmHg and the opening of anterior chamber were observed.RESULTS:After one hour,compared with the medical treatment group,the LPl group:symptoms and the corneal edema dissolved faster;the visual acuity rose more and fasten,the differences were statistically significant in IOP at 60,120 minutes after treatment in the two groups,however,no statistical difference at 30 minutes and 24 hours.Compared with IOL before treatment,there was no statistical difference at 30 minutes after treatment,but at 1,2,24 hours after treatment there was statistical difference in LPI group,so was the medical treatment group.The time used to lower IOP to 21mmHg and the opening of anterior chamber were statistically different in two groups(P<0.05).CONCLUSION:With an effective method,LPI can rapidly reduce the IOP of the acute attack of the PACG,especially better than medical treatment.