Ultrasound is a fundamental tool used in all medical specialties, including ophthalmology. Nowadays, ultrasound biomicroscopy (UBM), a method with higher resolution, allows the investigation of in vivo details of the anterior segment of the eye at microscopic resolution. The examination is especially useful in patients with secondary glaucoma that involves a lens component such as phacomorphic glaucoma and occult phacomorphic glaucoma (OPG). The purpose of this paper was to familiarize audience with UBM and the importance of this investigation in OPG, by presenting a series of cases in which performing an UBM was vital because it provided the information needed in order to safely accomplish a curative surgical treatment that preserved our patients' visual acuity.