Occult Wooden Posterior Segment Intraocular Foreign Body

Abstract

To evaluate B-scan and computed tomographic appearance of a wooden intraocular foreign body within the posterior segment. The authors report a case of a patient with an occult retained foreign body. To identify why the object was elusive, an in vitro study was conducted using computed tomography (CT) and B-scan on five human cadaveric eyes with known foreign bodies implanted into the vitreous cavity. Posterior segment metal and glass produced comet tail artifacts on B-scan, whereas stone, wood, and plastic produced shadowing artifacts. There was difficulty in identifying wood within the posterior chamber via CT. However, stone and plastic were easily detectable but difficult to identify without Hounsfield units. CT provides quick imaging of suspected posterior segment foreign bodies; however, B-scan ultrasonography may prove more useful than CT in detecting wooden foreign bodies.