Unilateral Ocular Siderosis Bulbi Due to Missed Metallic Intraocular Foreign Body Masquerading as Anisocoria of Neurological Origin: A Case Report.

BACKGROUND Ocular siderosis is an uncommon cause of vision loss due to a retained ferrous intraocular foreign bodies (IOFB) that cause iron deposition in ocular tissues. The most common manifestations are cataract formation, diffuse pigmentary changes of the retinal pigment epithelium, iris heterochromia, dilated pupils, secondary glaucoma, iritis, and cystoid macular edema. CASE REPORT We report a case of 38-year-old man who presented with a left dilated pupil and visual field defect. Neurological examination results were normal. Brain magnetic resonance imaging revealed a gross artifact at the site of the left globe. The visual field test showed a peripheral arcuate nasal visual field defect in the left eye. Ophthalmic examination revealed peripheral pigmentary changes and a black elongated and elevated lesion located very anterior and inferior-temporal and attached to the retina with fibrous tissue. A computed tomography scan revealed a 1×1-mm-round hyperdense IOFB in the left vitreous cavity. The diagnosis of siderosis bulbi secondary to a missed IOFB was established. The patient underwent a pars plana vitrectomy for removal of the IOFB. Two weeks later, rhegmatogenous retinal detachment developed, and repair with silicon oil injection was done. One year after the last operation, the best corrected visual acuity in the left eye was 6/120, with normal intraocular pressure and an attached posterior pole. CONCLUSIONS This case highlights the importance of investigating for a retained IOFB in cases of unilateral retinitis pigmentosa changes.