Cobalt-induced Retinopathy: Unveiling the hidden risk of knee prosthesis

To report a case of cobalt-induced retinopathy from a knee prosthesis and to outline the diagnostic challenges and management approach.

A 67-year-old female presented with chronic bilateral visual disturbances, including blurred vision and photopsia, which began shortly after receiving a cobalt-containing knee prosthesis (DePuy Sigma Total Knee System, recalled by FDA in 2014, Recall No. Z-0423-2014). Ophthalmic evaluation revealed bilateral chorioretinitis, cystoid macular edema, and optic disc inflammation. Removal of the cobalt-containing prosthesis, along with aggressive immunosuppressive therapy, led to significant improvement in visual acuity and retinal function, as confirmed by fluorescein angiography, electroretinography, and Goldmann visual field testing.

This case adds to the limited literature on cobalt-induced retinopathy by demonstrating that even small prosthetic implants, such as knee prostheses, can lead to systemic cobalt toxicity with significant ocular complications. Early diagnosis, combined with prompt removal of the affected prosthesis and management of inflammation, is crucial for restoring vision and preventing further damage.