Purpose To investigate the effects of intervention with Tanakan on anterior ocular segment in diabetic retinopathy (DR) after retinal photocoagulation． Methods Prospective random controlled study was performed on 72 patients (72 eyes) with ultrasound biomicroscopy (UBM),by obtaining and quantitatively analyzing the changes of anterior ocular segment including anterior chamber, anterior chamber angle, ciliary body and choroids before and the 3rd day and the 7th day after retinal photocoagulation. Results Three days after photocoagulation, significant elev ated IOP and narrowed chamber angle were observed in control group and 4 eyes (1 1.11%) in Tanakan group (Plt;0.01)． Choroidal detachment in 32 eyes (88.89%) in control group and in 2 eyes (5.56%) in Tanakan group and the severity of ciliochoroidal detachment in tanakan group was significantly lower than that in control group． Conclusion Tanakan is effective to prevent the complications of anterior segment, such as ciliochoroidal detachment, elevation of IOP, narrowing of chamber angle occurring early after retinal photocoagulation and reduce the severity of ciliochoroidal detachment． (Chin J Ocul Fundus Dis, 2001,17:187-189)