When Magnetic Resonance Imaging Awakens A 40-Year Silent Metallic Intraocular Foreign Body: A Case Of Anterior Segment Siderosis

To report a rare case of chronic anterior segment ocular siderosis secondary to a long-standing retained metallic intraocular foreign body (IOFB), revealed after magnetic resonance imaging (MRI)-induced displacement and managed surgically with good anatomical and functional outcomes.

Department of Ophthalmology, Centre Hospitalier de Poissy–Saint-Germain-en-Laye, Poissy, France.

A 55-year-old woman presented with progressive visual decline in her right eye over several months. She reported a penetrating ocular trauma at the age of 15 that had never been medically evaluated.While undergoing magnetic resonance imaging (MRI) for an unrelated condition, she developed acute ocular pain during the examination. The pain prompted her to seek ophthalmologic evaluation.

Slit-lamp examination revealed a linear paracentral corneal scar, a temporal iris defect associated with sectoral rust-colored stromal deposits consistent with iron deposition, and a traumatic cataract. The contralateral eye was clinically normal. Anterior segment imaging confirmed localized pigmentary changes suggestive of siderosis. Ultrasound biomicroscopy identified a highly reflective inferior intraocular foreign body with posterior acoustic shadowing, confirming its metallic nature. The overall clinical findings were consistent with chronic anterior segment ocular siderosis secondary to a retained metallic IOFB, likely mobilized following MRI exposure.

The patient underwent phacoemulsification with intraocular lens implantation, surgical removal of the metallic foreign body, and implantation of a coloboma ring to compensate for the temporal iris defect and restore pupillary configuration. Surgery was uneventful. Postoperatively, visual acuity improved significantly. Anatomical reconstruction of the anterior segment was satisfactory, with high patient-reported satisfaction.

Retained metallic intraocular foreign bodies may remain clinically silent for decades before manifesting as ocular siderosis. MRI exposure may induce foreign body mobilization, resulting in acute symptoms and structural damage. Unilateral cataract associated with sectoral iris pigmentation or defect should raise suspicion of occult metallic IOFB. Early recognition and surgical removal are essential to prevent progressive iron-induced ocular toxicity.