Experimental ocular siderosis in the squirrel monkey.

An iron-containing foreign body retained in the eye may result in siderotic damage to several ocular structures. When the retina is sufficiently damaged, the electroretinogram (ERG) becomes non-recordable. The pathogenesis of retinal damage has not been com­ pletely studied, and available histopathologic material is mainly of end-stage retinal le­ sions in eyes that were damaged severely enough to warrant enucleation. Even ophthalmoscopic observation of fundus lesions is difficult, since the media of the injured eyes are usually quite hazy. Characteristics of fluorescein angiography in siderosis are unknown for the same reason. We studied the early and mild retinal le­ sions experimentally, to understand more about the mechanism of retinal damage by iron. Elemental iron, ferrous iron, and ferric iron in different concentrations were injected through the pars plana into the vit­ reous of squirrel monkey eyes. The effects were studied at various time intervals by se­ rial ERGs, fluorescein angiography, fundus examinations, routine histopathology and histopathology with special iron stains, phase contrast microscopy, and electron micros­ copy.