A O S 1998 491 Ultrasound biomicroscopic localization and evaluation of intraocular foreign bodies Daniel Laroche 1 , Hiroshi Ishikawa 1,3 , David Greenfield 1,2 , Jeffrey M. Liebmann 1,2 and Robert Ritch 1,2 Departments of Ophthalmology, 1 The New York Eye and Ear Infirmary, New York, NY, 2 New York Medical College, Valhalla, NY, and 3 Mie University School of Medicine, Japan. ABSTRACT. Purpose: To evaluate the ultrasound biomicroscopic appearance of anterior seg- ment foreign bodies under clinical and experimental conditions. Methods: Ultrasound biomicroscopy was performed on 4 eyes of 4 patients referred for evaluation of anterior segment trauma and known or suspected intraocular foreign body. Imaging of wood, aluminum, concrete, and glass for- eign bodies was performed in the anterior chamber of a human cadaver eye. Results: Ultrasound biomicroscopy verified the location of a foreign body in two patients and identified occult foreign bodies in two others. Under clinical and experimental conditions, intraocular aluminum and glass produced comet tail artifacts. Under experimental conditions intraocular wood and concrete pro- duced shadowing artifacts. Conclusion: Ultrasound biomicroscopy provides useful information in the evalu- ation of known and occult anterior segment foreign bodies. Ultrasound patterns of shadowing and comet tail may help differentiate foreign body materials. Key words: ultrasound biomicroscopy – intraocular foreign body – anterior segment – trauma. Acta Ophthalmol. Scand. 1998: 76: 491–495 Copyright c Acta Ophthalmol Scand 1998. ISSN 1395-3907 T rauma is a leading cause of visual impairment. The initial evaluation of ocular trauma when a retained intrao- cular foreign body (IOFB) may be pres- ent is crucial in determining the site(s) of injury and planning appropriate thera- peutic strategies. There are limitations to traditional methods of evaluating an- terior segment trauma. Slit lamp biomic- roscopy requires clear media and par- ticles buried in tissue cannot be discern- ed. B-scan ultrasonography cannot identify small foreign bodies. Routine X- ray examination might identify some small IOFB, but localization is poor. Computed tomography may not be able to identify objects which fall between the scanning sections. Tissue discrimination by magnetic resonance imaging is excel- lent, but is contraindicated when a met- allic foreign body is suspected. Ultrasound biomicroscopy (UBM) permits high resolution in vivo imaging of the anterior segment of the eye (Pavlin, et al. 1991; 1992; Pavlin and Foster 1995) and is useful in the evaluation of anterior segment trauma (Karwatowski & Wein- reb 1994; Milner et al. 1994; Gentile et al. 1996; Berinstein et al. 1997) This tech- nology is based upon the use of a high frequency transducer incorporated into a B-mode scanning device (Pavlin et al. 1990; 1991). Skips in image slices that can occur with MRI and CT scanning are avoided and patients with opaque media can be imaged effectively. Conventional B-scans can image larger foreign bodies, but UBM provides a cleaner image and a better view of surrounding structures. We evaluated four patients with traumatic ocular injuries in which retained anterior segment foreign bodies were imaged using UBM. We then obtained clinico- pathologic correlation using eye bank eyes. We compared the UBM appearance of various intraocular foreign bodies (IOFB) to the cadaver model. Patients and Methods Four eyes of four patients with anterior segment foreign bodies had complete ophthalmic examinations and ultrasound biomicroscopy (Zeiss-Humphrey, Inc., San Leandro, Calif, 50 MHz transducer). Multiple cross-sectional images were taken over 360 degrees in each eye and projected on a video monitor. Selected images were saved for later recall and interpretation. One intact, structurally normal human globe was studied in vitro. The intraocul- ar volume was restored with an intravitre- al injection of water. We manufactured foreign body particles of glass, alumi- num, concrete and wood measuring ap- proximately 1.0 mm in length, 0.5 mm in width and 0.2 to 0.3 mm thick. A self sea- ling 3-step incision was made at the lim- bus. The anterior chamber was reformed with sodium hyaluronate (Healon, Pharmacia and Upjohn, Kalamazoo, MI) and one foreign body was placed in each quadrant. UBM was then performed. Results Case Reports Case 1: A 37-year-old man sustained ocu- lar trauma to his left eye while ham- mering metal. Best corrected visual acu- ity was 20/30. Intraocular pressure (IOP)