Ocular siderosis: a misdiagnosed cause of visual loss due to ferrous intraocular foreign bodies—epidemiology, pathogenesis, clinical signs, imaging and available treatment options

Abstract

Purpose The purpose of this paper is to provide a meaningful literature review about the epidemiology, pathogenesis, clinical signs, imaging and treatment of ocular siderosis (OS). Methods A computerized search from inception up to March 2020 of the online electronic database PubMed was performed using the following search strings: “ocular siderosis” and “siderosis bulbi”. The reference list in each article was analysed for additional relevant publications. Results OS is an uncommon cause of visual loss due to a retained ferrous intraocular foreign body (IOFB). It may develop from 18 days to years after a penetrating trauma that usually occurs during hammering. On average, patients are 22–25 years old, and the vast majority are male. The most common cause of OS development is delayed presentation by the patient or missed diagnosis of IOFB after trauma. The pathophysiology is not fully understood; nevertheless, iron deposition causes hydroxyl radical formation, which damages photoreceptors and retinal pigment epithelium. Moreover, iron damages retinal vessels with consequent inner retinal layers degeneration. The most frequent signs are iris heterochromia, pupillary mydriasis, cataract development and retinal arteriolar narrowing with pigmentary retinal degeneration. Electroretinogram signs, in particular, b-wave amplitude reduction, arise earlier than clinical signs. Orbital CT scans and ultrasonography play an essential role in detecting IOFBs. Treatment depends on the IOFB location and OS development. However, it is crucial to remove the IOFB after OS development because visual acuity and clinical signs may improve. Anterior segment IOFBs can be dislodged using an intraocular magnet (IOM) or forceps through limbal paracentesis. In contrast, posterior segment IOFBs require a pars plana vitrectomy and IOM or forceps to be removed through an enlarged sclerotomy or the limbus. Conclusion Recommending the usage of protective glasses and spreading knowledge about OS may further benefit patient care.

Clinical Characteristics and Visual Outcomes in Patients with Intralenticular Foreign Bodies with Self-Sealing Corneal Penetrating Wounds

“…BCVA after surgery was equal to or better than 20/32. When an IOFB cannot be found during ophthalmological evaluation, tools, including plain radiography, ultrasonography, ultrasound biomicroscopy, orbital computerized tomography scanning, magnetic resonance imaging, and optical coherence tomography, are available to aid in IOFB diagnosis [11,22]. Ultrasonography and computerized tomography are more sensitive methods for detecting all types of IOFBs [23].…”

“…Siderosis bulbi, one of the most serious complications, may be caused by retention of an iron-containing IOFB, which can cause deposition of iron molecules in the ocular tissues [9,10]. e clinical findings of siderosis bulbi include iris heterochromia, pupillary mydriasis, cataract formation, secondary glaucoma, retinal arteriolar narrowing, retinal pigmentary degeneration, optic disc swelling or hyperemia, and cystoid macular edema [9][10][11][12]. Without a complete examination, intralenticular foreign bodies (ILFBs) may be missed and therefore retained in patients with small self-sealing wounds who present with no decreased visual acuity [13,14].…”

A rare asymptomatic metallic intraocular foreign body retained in the anterior chamber for 15 years

“…ffERG is the gold standard for detecting retinal damage, such as toxic retinopathy and cone-rod dysfunction caused by iron IOFB, because it can reveal retinal dysfunction before any pathological changes. [ 12 ] Casini et al [ 13 ] mentioned that OS could be reversible and that ffERG amplitudes may increase after IOFB removal. We did not perform ffERG before the surgery; however, the postoperative ffERG showed decreased “b” and “a” waves 3 months after IOFB removal.…”

Value of Ocular Endoscopy in Extraction of Intraocular Foreign Bodies of Cilia in Patients with Open Ocular Trauma

“…As a type of autogenic biological foreign body, the eyes’ reaction to cilium varies unpredictably. Whether cilia foreign bodies in the posterior segment have to be removed or not through an operation depends on the situation [ 10 ]. Intraocular cilium have been reported to be asymptomatic for 50 year in the anterior chamber [ 11 ].…”