To study the changes of the ocular anterior segment structure and the mechanism of angle-closure glaucoma after scleral buckling surgery.30 patients (33 eyes) who suffered from rhegmatogenous retinal detachment had been observed before and 3 - 7 days after the surgery. The quantitative measurement of the ocular anterior segment structure in vivo had been done by ultrasound biomicroscopy (UBM). The results were statistically analyzed.There was one eye with split-like ciliary body detachment before the surgery, there were 11 eyes with ciliary body detachment (33.3%) and the ciliary body was thickened and edematous after surgery. Before the surgery the thickness of the ciliary body was (821.32 +/- 64.21) microm and after the surgery it was (945.27 +/- 104.16) microm, the difference being statistically significant, P < 0.05. Parameters reflecting the changes of the anterior chamber angle before and after surgery were as follows: the anterior chamber angle became narrower, the angle open distance 500 decreased, the trabecular-iris angle decreased in degree, the angle of the scleral lateral side and iris long axis decreased, and all these differences were statistically significant, P < 0.05, but the depth of the central anterior chamber had no obvious change, and the difference was not statistically significant, P > 0.05.Ciliary body detachment and edema are often found after scleral buckling surgery, and post-operatively the central anterior chamber depth has no obvious change; ciliary body detachment and edema perhaps are related to the angle-closure glaucoma after the surgery.