Ultrasound biomicroscopy as a tool for detecting and localizing occult foreign bodies after ocular trauma

Objective: To show the utility of ultrasound biomicroscopy (UBM) in imaging small ocular foreign bodies of the anterior segment. Design: Retrospective case series. Participants: Twelve eyes of 12 consecutive patients evaluated in the emerg ency department or referred to specialty services at 1 institution between August 1994 and November 1997 were examined. Intervention: Ocular ultrasound biomicroscopy was performed. Main Outcome Measures: Detection and localization of an ocular foreign body were measured. Results: An intraocular or superficial foreign body was detected by UBM in 9 (75%) of 12 eyes. The foreign body was classified as corneal in two eyes, subconjunctival in two, intrascleral in three, and intraocular in two eyes . The foreign body was not visible by ophthalmic physical examination in se ven of the nine eyes with a confirmed ocular foreign body. In the remaining two eyes, UBM was used to determine the depth of a visible foreign body. I n three of the eyes with a confirmed foreign body, computed tomography and/ or contact B-scan ultrasonography was obtained and failed to show a foreign body. Six of the foreign bodies were nonmetallic. Conclusions: Clinical detection of ocular foreign bodies after trauma can b e hindered by small size, haziness of the optical media, poor patient coope ration, or hidden location. Ultrasound biomicroscopy is a valuable adjunct in the evaluation of suspected ocular foreign bodies, especially in cases i nvolving small, nonmetallic objects.