A new method of 3-dimensional localization of intraocular foreign bodies using CT imaging: A role of optic nerve.

Computed tomography (CT) is considered the most sensitive method for the detection of intraocular foreign bodies (IOFBs). The purpose of this study was to evaluate a new method of 3-dimentional (3D) localization of IOFBs that takes advantage of the anatomical structure of the optic nerve and to assess the clinical outcomes using this new method. Twenty-two trauma patients with IOFBs or suspected IOFBs admitted to our hospital were scanned with multislice CT (MSCT) between July and December 2003. All scanning was performed with a 16-row spiral CT in axial plane using a sequential scanning protocol. During the scanning, the eyeball of the patient was kept stable and was not allowed to rotate internally or externally. Section collimation was set at 16 mm × 0.75 mm. Table feed was 12 mm. Reconstruction index was 0.75 mm. After scanning, the reconstructed images were loaded into a workstation to create the multiplanar reconstruction images with the aid of the 3D software. We compared the localization results with the operative findings. Multiplanar reconstruction images showed IOFBs in all 22 patients. IOFBs occurred in the eyeball of 14 patients, in the wall of the eyeball of 5 patients and in the posterior orbits of 3 patients. Different surgical procedures were designed according to the localization by this new method and all IOFBs were successfully removed. All of these foreign bodies were metallic and the localization of IOFB using MSCT was consistent with that found by operative findings. It was suggested that MSCT is a simple and effective imaging modality for the localization of IOFBs. In our study, we localized the IOFBs more quickly and accurately by taking advantage of the fixed position of the intraocular segment of the optic nerve, and determined the necessary surgical parameters.