Ocular siderosis secondary to occult intraocular foreign body causing secondary glaucoma: A case report

Abstract

BACKGROUND

Occult intraocular foreign bodies (IOFBs) can present with atypical symptoms and clinical signs, making diagnosis challenging. We describe a case of an undetected IOFB that was missed on both computed tomography and B-ultrasound, ultimately leading to ocular siderosis and secondary glaucoma.

CASE SUMMARY

A 55-year-old male patient presented to our clinic reporting a one-month history of right ocular discomfort and progressive visual deterioration. The patient had previously received a glaucoma diagnosis at a local healthcare facility. His ocular history included blunt trauma to the affected eye five years prior to presentation. Slit-lamp examination revealed corneal and iris lesions in the right eye. Pupillary dilation facilitated the identification of traumatic lens opacities. Diagnostic imaging modalities, including B-scan ultrasonography and computed tomography, showed no evidence of retained intraocular foreign material. The patient subsequently underwent uncomplicated pars plana vitrectomy, during which the occult foreign body was successfully extracted. The procedure was completed without intraoperative or immediate postoperative complications.

CONCLUSION

Awareness of IOFBs in individuals who work in high-risk occupations and prompt referral to a retinal surgeon are very important.

Key Words: Missed intraocular foreign body; Ocular siderosis; Secondary glaucoma; Occult; Ocular trauma; Case report

Core Tip: Occult intraocular foreign bodies can lead uncommon symptoms and signs. We report a case of an occult intraocular foreign body which computed tomography and B-ultrasound were not detected causing ocular siderosis and secondary glaucoma.

INTRODUCTION

Occult intraocular foreign bodies (IOFBs) represent a substantial proportion (18%-41%) of penetrating ocular trauma cases[1]. These retained objects significantly elevate the risk of severe ocular sequelae, including endophthalmitis, lens opacification, detachment of retinal tissue, and elevated intraocular pressure (IOP). Prompt identification is crucial in clinical management, as diagnostic oversight may result in irreversible vision loss[2]. We describe a patient who developed siderosis bulbi and secondary glaucoma secondary to an undetected metallic intraocular foreign body. This condition manifests through characteristic iron-induced degenerative changes in ocular tissues. While computed tomography (CT) imaging and ultrasound examinations are generally reliable for IOFB detection, they failed to identify the foreign material in this particular case, creating significant diagnostic difficulties[3,4]. This report highlights the potential for false-negative results in IOFB diagnosis and the catastrophic consequences of missed cases[5]. The patient ultimately achieved favorable visual outcomes following successful surgical extraction of the retained metallic fragment, underscoring the importance of maintaining clinical suspicion even when imaging studies prove inconclusive[6].

CASE PRESENTATION

Chief complaints

A man complaint right eye pain about 5 days.

History of present illness

A 55-year-old construction worker sought evaluation at our facility due to acute visual impairment and discomfort in his right eye.

History of past illness

A 55-year-old male employed in construction sustained an ocular injury five years ago when he noticed a foreign particle entering his right eye. Despite this incident, his visual acuity remained largely unaffected. Initial evaluations at a nearby medical facility, including CT and ultrasonography, revealed no IOFBs. Subsequently, approximately one year before presentation, he became aware of progressive vision deterioration. Upon further assessment at a local clinic, he was diagnosed with cataracts, and repeat imaging via CT showed no evidence of retained foreign material.

Personal and family history

The patient reports no significant medical comorbidities, including hypertension, diabetes, or cardiovascular conditions. He also has no known history of transmissible infections or familial genetic abnormalities. Five years ago, he sustained a traumatic ocular injury involving a foreign body entering his right eye.

Physical examination

Visual acuity testing demonstrated 20/60 in the right eye and 6/6 in the left. Slit-lamp evaluation of the right eye showed an inferior temporally located oblique corneal scar, which appeared well-healed, along with an adjacent iris defect underlying the scar. The pupil was mydriatic, with a brunescent cataract and pigmented deposits evident on the anterior lens capsule (Figure 1).

Figure 1 The right eye had a corneal, self-sealed corneal scar, with siderotic pigments on the cataractous lens (blue arrow). The right eye had a self-sealed capsular wound at the paracentral 5:00 position (white arrow), along with a corresponding iris defect beneath the corneal wound (yellow arrow).

Laboratory examinations

IOP was measured at 48 mmHg with a Goldmann applanation tonometer.

Imaging examinations

Perimetry demonstrated concentric constriction of the visual field in the right eye (Figure 2). B-scan ultrasonography showed an optically clear vitreous humor with attached retina. Ultrasonic biomicroscopic evaluation meticulously assessed all meridians, with particular attention to the inferotemporal quadrant adjacent to the corneal scar and its contralateral region, but detected no IOFBs (Figure 3). Multiplanar orbital CT imaging (axial, sagittal, and coronal reconstructions) confirmed the absence of radiopaque intraocular foreign material (Figure 4).

Figure 2  Visual field testing revealed tubular vision in the right eye.

Figure 3 No intraocular foreign bodies was detected on the B-scan. Ultrasonic biomicroscopy image of the right eye. This image shows no detectable intraocular foreign bodies in the anterior chamber, iris stroma, ciliary body, or pars plana.

Figure 4 Coronal plain computed tomography of the orbit revealed no detectable intraocular radiopaque foreign bodies. A: In both the axial views; B: In both the frontal views.

FINAL DIAGNOSIS

Intraocular foreign body, ocular siderosis, secondary glaucoma, cataract, ocular trauma.

TREATMENT

Following successful IOP stabilization, the patient underwent phacoemulsification with pars plana vitrectomy. Intraoperative exploration unexpectedly revealed a previously undetected intraocular foreign body, which was carefully extracted (Figure 5). Postoperative management included topical hypotensive medications, maintaining stable pressure at 14 mmHg. Secondary intraocular lens implantation was successfully performed seven days later, with the lens securely positioned within the capsular bag.

Figure 5 Inspection result. A-C: The intraocular foreign body removed from the retina during vitreous surgery (the arrow in B indicates that the intraocular foreign body was located superior to the retina); D: Shows that the retinal and macular structures had recovered well 1 week after the operation; E: Showing that the fundus photography had recovered well 1 week after the operation.

OUTCOME AND FOLLOW-UP

Postoperatively, the patient’s IOP was 13 mmHg, and his visual acuity was 50/60.

DISCUSSION

Siderosis is a distinct clinical entity caused by iron deposition in intraocular tissues, primarily affecting structures such as the iris and lens. Common manifestations include iris heterochromia (58.33%) and cataract formation (95.83%)[7], while retinal pigmentary degeneration occurs in 58.33% of cases[4,7,8].

Siderotic glaucoma, a rare but vision-threatening complication, often results from retained iron IOFBs. We present a case of a 55-year-old man with medically unresponsive secondary open-angle glaucoma, later linked to a self-sealed corneal wound from penetrating trauma five years prior. Despite CT and B-scan ultrasound failing to detect the occult metallic IOFB, clinical findings confirmed siderosis bulbi. Surgical removal of the foreign body normalized IOP and improved vision, underscoring the need for detailed slit-lamp and fundus examinations in trauma cases. Early surgical intervention and long-term monitoring are critical to prevent irreversible vision loss[3].

Retained intraocular iron induces toxicity through oxidative stress, particularly in ectoderm-derived tissues. This process disrupts cellular enzymes, damages membranes, and generates lipid peroxides, culminating in vision loss. Onset varies widely (18 days to decades post-injury)[9,10], and delayed presentation often leads to missed diagnoses. Prognosis depends on the timing of foreign body detection and removal, emphasizing the need for prompt recognition and management to preserve visual function.

Secondary open-angle glaucoma is a frequent complication, developing two months to 30 years post-trauma[11,12]. Proposed mechanisms include: Trabecular meshwork obstruction by iron-laden macrophages or particles, impairing aqueous humor outflow. Albuminous aqueous production by the ciliary body, elevating IOP. Direct iron toxicity, causing trabecular fibrosis and further outflow dysfunction[3,11,12].

While CT is the gold standard for IOFB detection[4], its efficacy depends on scanner resolution, foreign body size, and location. In our case, a 2 mm slice thickness and possible iron dissolution over time likely contributed to the false-negative imaging results. B-scan ultrasound, though useful, is operator-dependent and less reliable for chronic iron IOFBs due to metallic degradation[4,13].

Early IOP monitoring, optic nerve assessment, and visual field testing are vital for at-risk patients. A high index of suspicion, coupled with multimodal imaging and timely intervention, can mitigate vision loss in siderosis-related glaucoma.

CONCLUSION

In this case, pars plana vitrectomy achieved successful IOFB removal, resolving symptoms and improving visual acuity. This outcome highlights the importance of timely diagnosis and surgical intervention in managing this rare complication. Siderosis bulbi, though uncommon, poses significant vision-threatening risks due to retained iron-containing IOFBs. Early detection and extraction of IOFBs are critical to preventing irreversible ocular damage and preserving visual function[8]. Advanced imaging (CT, B-scans) and electrophysiologic testing enhance diagnostic accuracy and inform treatment strategies. A multidisciplinary approach integrating ophthalmologists, radiologists, and surgeons is essential for optimal patient outcomes. Overall, collaborative care ensures comprehensive evaluation, precise intervention, and long-term monitoring to mitigate complications.

ACKNOWLEDGEMENTS

I would like to thank the anesthesiologists and nurses as well as the doctors in the central examining room.