['To determine if pars plana vitrectomy induces long-term changes in the anterior segment anatomy by means of ultrasound biomicroscopy.', 'A prospective case series study was undertaken of consecutive patients referred to a tertiary eye care centre for pars plana vitrectomy as the only procedure. Twenty eyes of 20 patients undergoing pars plana vitrectomy alone were studied by ultrasound biomicroscopy. Silicone oil or scleral buckle was not used in any of the included cases. The following morphometric parameters were compared before and after 3 months of surgery: anterior chamber depth, angle-opening distance at 500 microm from the scleral spur, trabecular-ciliary process distance, ciliary body thickness at 1, 2 and 3 millimeters from the scleral spur and measurement of the supraciliary space thickness, when fluid was detected.', 'No statistically significant differences were found between the preoperative and the postoperative morphometric parameters.'] Do ultrasound biomicroscopy in the comparison of the anterior segment morphometry before and after pars plana vitrectomy?