2020–2021 BCSC Basic and Clinical Science Course™
2 Fundamentals and Principles of Ophthalmology
Part VI: Imaging
Chapter 17: Principles of Radiology for the Comprehensive Ophthalmologist
Ultrasonography
Ultrasound Biomicroscopy
Ultrasound biomicroscopy (UBM) utilizes the highest frequency available in ophthalmic ultrasonography, usually 50 MHz, with axial resolution of 37 µm, and is used to evaluate the anterior segment of the eye. It requires topical anesthesia and a fluid reservoir, which is placed in direct contact with the cornea and/or anterior sclera depending on which structures need to be evaluated. Two types of scans are obtained with UBM depending on the orientation of the probe. Axial UBM scans are generated by placing the probe on the cornea positioned horizontally (Fig 17-14). This allows visualization of the cornea, the anterior chamber, the iris with the pupil in the center of the iris plane, and the lens. Radial UBM scans are generated by centering the probe at the limbus, with the marker oriented perpendicular to the limbus. The anterior chamber angle, iris, and ciliary body can be evaluated with this scan (Fig 17-15).
Table 17-5 B-Scan: Tissue-Specific Gain Setting
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.