AIM:To evaluate the efficiency and safety of selective laser trabeculoplasty (SLT) on primary open angle glaucoma (POAG) and compare the effect under different condition:POAG with previous trabeculoplasty,POAG with medical therapy and POAG without therapy.·METHODS:46 eyes of 46 patients with uncontrolled POAG(group A with previous trabeculectomy,group B with medical therapy and group C without therapy)were treated with a frequency-doubled,Q-switched Nd:YAG laser,intraocular pressure(IOP)was measured 1 hour,1 day,1 week and 1,3,6 months after treatment.·RESULTS:The average IOP was(16.9±3.2)、(18.7±3.3)、(18.9±3.3)、(19.8±3.2)、(20.0±3.4)mmHg at 1 day,1 week and 1,3,6 months after SLT,respectively.There was significant IOP decrease after SLT and no difference among group A,B and C.·CONCLUSION:SLT is an effective and safe method to lower IOP of POAG no matter whether the patient had previous trabeculoplasty,medical therapy or without therapy.