Radiologic Differentiation of Intraocular Glass

Abstract

OBJECTIVE: The accurate detection of intraocular foreign bodies is critically important in treating ocular trauma. The purpose of this study was to evaluate the efficacy of CT, MR imaging, and sonography in detecting seven types of glass varying in size and placed in three locations in the globe, and to examine the effect of intraocular hemorrhage. MATERIALS AND METHODS: Glass pieces were cut into 1.5-, 1.0-, and 0.5-mm pieces and implanted on the corneal surface and the anterior and posterior chambers of 42 fresh porcine eyes. Twenty-one eyes were scanned comparing axial CT, helical CT, and MR imaging. The remaining 21 eyes were scanned using helical CT and sonography after implantation in a simulated human skull before and after placement of blood in the anterior chamber (hyphema). RESULTS: Detection rates were 57.1% for helical CT, 41.3% for axial CT, and 11.1% for T1-weighted MR imaging (n = 63 fragments). Results were significant (p < 0.0001). Sonography detected 43% of glass fragments in the posterior chamber and 24% in the anterior chamber. Detectability was greatest for green beer bottle glass (90.3%) and least for spectacle glass (43.1%) (p < 0.0001). Detection rates for size ranged from 96.2% at 1.5 mm to 48.3% at 0.5 mm, which was also significant (p < 0.0001). On helical CT, anterior chamber glass was easiest to detect (91.7%) and corneal surface glass the most difficult (64.9%). Hyphema made no statistical difference (p < 0.0001). CONCLUSION: Helical CT was the most sensitive imaging modality for the detection of intraocular glass. The sensitivity of detection was unaffected by hyphema but was determined by the type of glass, size, and location.