Composition of intraocular foreign bodies: Experimental study of ultrasonographic presentation

Abstract

Purpose: To investigate the reliability of ultrasound in determining the size and identify the sonographic features and artifacts generated by intraocular foreign bodies of different materials. Methods: Experimental study using 36 enucleated porcine eyes. Fragments ofnine different compositions (wood, glass, plastic, cardboard, iron, aluminum, lead, powder and concrete) and similar dimensions (4 mm) were implanted via scleralincision into the vitreous cavity of 36 porcine eyes, four eyes were used for each material. Ultrasound examination was performed in all eyes using the contact technique, conductive gel and 10-MHz transducer (EZScan, Sonomed).Results: Considering the material fragments of gunpowder, lead, concrete, aluminum, wood and glass, the size determined by ultrasound was consideredstatistically similar to the actual size. The material iron presented ultrasound-determined dimension statistically smaller than its actual size. Cardboard and plasticmaterials showed ultrasound-determined measurements far greater than theactual. All fragments of intraocular foreign bodies demonstrated hyper-reflectiveinterfaces, irrespective of their composition. Whereas the artifacts generated bydifferent materials, it was found that the materials iron, aluminum and lead showedreverberation of great extent. The material wood showed no reverberation. Thelength of the reverberation artifact for the materials iron, glass, aluminum andcardboard was lower when compared to other materials. All materials presentedposterior shadowing artifact, with the exception of aluminum. Conclusion: Ultrasonography was considered a reliable technique to determinethe size of intraocular foreign bodies in pigs, with little influence caused by itscomposition. Ultrasound artifacts generated were considered material-dependentand can assist the examiner to identify the nature of a foreign body of unknownetiology. Ultrasonography aided the surgeon to identify, locate and measure the intraocular foreign body, directing appropriate surgical planning.