Occult penetrating globe injuries with retained IOFBs are a relatively infrequent occurrence [1
] and may rarely present with chronic anterior or posterior segment inflammation [2
]. Besides meticulous ophthalmic examination, B-scan ultrasound, ultrasound biomicroscopy, and CT scans are extremely useful in the diagnosis of occult IOFB injuries. ERG changes have been characterized in the context of siderosis associated with IOFB injuries [1
]. In addition, retained copper IOFBs may result in acute [1
] or chronic chalcosis [7
]. In both siderosis and chalcosis, ERG changes may be partially reversible in some patients [10
Following PPV/IOFB extraction and retinal detachment repair, our patient's visual acuity was decreased despite a successful surgical outcome. Because of the mild anterior chamber inflammation and retinal hemorrhage observed OS, there was also suspicion for early sympathetic ophthalmia. For these reasons, electrophysiology was performed and revealed a reduction in rod and dark-adapted cone responses in both eyes, albeit to a much greater degree OD.
The ERG findings were most consistent with siderosis OD and were partially reversible with repeat testing. Contralateral ERG abnormalities have not been reported in the context of siderosis, but fortunately, these changes completely reversed on repeat testing. For this reason, the patient was treated only with routine postoperative medications, and systemic immunosuppression was deferred. Prior reports analyzing the heavy metal content of IOFBs have used diagnostic X-ray spectrometry [12
] and the percentage copper content of an IOFB likely plays a role in the degree of copper dissemination and associated toxicity.
In one prior patient reported with a copper IOFB, an undiluted vitreous sample showed an inflammatory reaction consisting of CD3+
T lymphocytes and polymorphonuclear leukocytes [13
]. Our patient demonstrated moderate inflammation prior to PPV/IOFB removal and the low-grade inflammation in the contralateral eye was suspicious for an autoimmune reaction. It is not clear whether this represented early sympathetic ophthalmia, but the inflammation OS completely resolved without medical therapy. We hypothesize that, following the initial IOFB injury, the intraocular inflammation was due to the toxic effects of the iron fragment. IOFB extraction led to a decrease in localized ocular inflammation and a resultant improvement in the ERG findings. The etiology of the contralateral eye inflammation is not clear; however, the mild anterior chamber inflammation in the contralateral eye had resolved at final follow-up.
ICP-MS is an extremely sensitive technique capable of detecting metal fragments approaching 1 part in 1012 (parts per trillion) and was extremely valuable in identifying iron as the predominant heavy metal in the IOFB; copper was found in minimal quantities. Reversal of ERG abnormalities has been described previously following IOFB extraction, and based on the patient's clinical course, the patient's visual prognosis remains favorable. He is under surveillance for the development of sympathetic ophthalmia given his occult penetrating globe injury.