In Vivo Imaging of Cobalt-Induced Ocular Toxicity in a Mouse Model

Cobalt is a trace element, crucial for red blood cell formation and neurological function. Cobalt toxicity is often only diagnosed after severe manifestations, including visual impairment. We aimed to investigate whether optical coherence tomography (OCT) and magnetic resonance imaging (MRI) can effectively detect cobalt-induced ocular toxicity in a murine model. Five wild-type mice (WT, C57Bl6) received daily intraperitoneal cobalt chloride injections for 28 days with a dosage of 12.5 mg/kg. Another 5 WT mice served as controls. After 28 days, all mice underwent manganese contrast-enhanced MRI and OCT examinations. Macroscopic and histological analysis of the enucleated eyes were performed. MRI revealed an increased signal in the optic nerves of injected mice. Anterion OCT provided in vivo visualization of the entire eye, demonstrating incipient cataract formation in the cobalt-injected mice. Both Spectralis domain OCT and Anterion, followed by histological analyses, confirmed preserved retinal structure with decreased thickness in the cobalt-injected group, with only minor neuronal damage and cell loss. Optic nerve analysis demonstrated myelin loss and increased inflammation with high levels of reactive gliosis. This study demonstrates optic neuropathy induced by cobalt toxicity, as shown by increased optic nerve signal on MRI without significant retinopathy. Anterion OCT showed incipient cataracts in the anterior segment.