Purpose To evaluate the long-term morphologic changes in the anterior segment structures after nonpenetrating filtering surgery (NPFS) supplemented with 5-fluorouracil (5-FU) and no scleral implant using ultrasound biomicroscopy (UBM). Methods Thirteen eyes of 13 consecutive patients who underwent NPFS with intraoperative 5-FU under the conjunctiva and the scleral flap and no implant were evaluated in an observational nonrandomized, consecutive case series study conducted 2 years postoperatively. Patients were assessed for the presence of a subconjunctival filtering bleb, the volume of an intrascleral cavity, and a suprachoroidal hypoechoic area. The intraocular pressure (IOP) was measured preoperatively and postoperatively at the time of UBM. Results The IOP decreased significantly (p=0.01) from 24±7.6 mmHg to 13.7±4.1 mmHg. In most patients (69.2%), the postoperative IOP decreased at least 30% from the preoperative value without medications and in 84.6% with medication. UBM showed a subconjunctival empty space in 92.3% of eyes. In 84.6% of patients, an intrascleral cavity was seen, the mean volume of which was 1.68 mm3 (range, 0–4.07). We found a negative correlation between the height, width, and volume of the intrascleral lake and the IOP. In 92.3% of eyes, a hypoechoic area in the suprachoroidal space also was seen. Conclusions UBM showed a filtering intrascleral cavity, subconjunctival filtering bleb, and a suprachoroidal space after NPFS supplemented with 5-FU under the conjunctiva and the scleral flap without an implant.