Role of B-scan ultrasonography in the localization of intraocular foreign bodies in the anterior segment: a report of three cases

Background: The accurate localization of intraocular foreign bodies (IOFBs) is very important for the management of ocular trauma patients. B-scan ultrasonography is usually used to detect IOFBs in the posterior segment. Here, we report three cases with IOFBs in the anterior segment near the posterior lens capsule, which were accurately localized by B-scan ultrasonography under dynamic transversal scanning. Case presentation: All three patients had a history of ocular trauma, and their clinical symptoms were compatible with the persistence of IOFBs. It was difficult to get a direct visualization of IOFBs with slit-lamp biomicroscopy because of opacities of the cornea and traumatic cataract. A computed tomography scan detected IOFBs in the anterior segment, but could not determine the exact location. Ultrasound biomicroscopy was performed but failed to show any IOFBs owing to the limited depth of penetration. B-scan ultrasonography was further applied but also failed to show any intraocular foreign bodies using axial scanning, a routine procedure of B-scan ultrasonography examination. However, using dynamic transversal scanning of B-scan ultrasonography, the accurate location of IOFBs was eventually shown to be embedded in the posterior lens cortex in case 1, adjacent to the posterior lens capsule in case 2, and located in the anterior vitreous close to the posterior lens capsule in case 3. Different surgical procedures were designed according to localization by B-scan ultrasonography, and all IOFBs were successfully removed. Conclusion: B-scan ultrasonography is a simple and effective imaging modality in the localization of IOFBs in traumatic cataract. Transversal scanning is more suitable than axial scanning to detect IOFBs in the anterior segment near the posterior lens capsule.