Aim To evaluate the effects of phacoemulsification on intraocular pressure (IOP) and ultrasound biomicroscope (UBM) images of filtering bleb in eyes with cataract and a previous functioning filtering bleb. Methods The IOPs and UBM images of filtering bleb of 24 patients (27 eyes) who underwent phacoemulsification after successful trabeculectomy were recorded at each follow-up examination and at the 12 months after phacoemulsification, respectively. Preoperative IOP and two parameters of the UBM images, including visibility of a route under the scleral flap and reflectivity inside the bleb were evaluated for an association with postoperative success rate using Kaplan-Meier survival analysis.