Scanning Electron Microscopy-Energy Dispersive Spectroscopy Evaluation of a Retinal Explant Model of Iron Intraocular Foreign Body Injury.

Iron intraocular foreign body (IOFB) can cause retinal damage, which may be related to the release, transfer, and tissue infiltration of iron particles. Sustained retinal impairment may occur after surgical removal of an iron IOFB, while direct in situ evidence of residual retinal iron deposition remains limited. A retinal explant model combined with regional scanning electron microscopy (SEM)-energy-dispersive spectroscopy (EDS) was used to examine retinal morphology and elemental distribution after iron foreign body exposure and removal. SEM analysis showed that, in the Fe group, the retinal surface at the foreign body bed was rough, with exposed blood vessels and scattered visible particles, whereas the control group showed a dense and intact retinal structure. Regional EDS analysis showed that iron was not detected in the control group but was elevated at the foreign body bed (Fe-Bed) in the Fe group (k-ratio: 0 ± 0 vs. 0.082 ± 0.040, n = 3, P < 0.05), with abnormal distributions of potassium and calcium also observed (k-ratio: 0.001 ± 0.002 vs. 0.013 ± 0.006 and 0.001 ± 0.003 vs. 0.014 ± 0.006, n = 3, all P < 0.05). Iron deposition was further detected in the contralateral distal retinal region (Fe-Far) of the Fe group (k-ratio: 0.036, n = 1). Comparison of the defined regions demonstrated that residual iron was not restricted to the direct contact area after removal of the iron foreign body. These findings confirm persistent iron retention in local and distal retinal tissue after foreign body clearance. The regional SEM-EDS explant platform provides a practical laboratory approach for detecting residual retinal iron and examining associated elemental changes after iron IOFB exposure. This method can be used to investigate IOFB-related iron accumulation-mediated retinal damage in an ex vivo experimental setting.