Pathology of the pigment epithelium and retina in rabbits poisoned with lead

Multifocal lesions of the retinal pigment epithelium were observed in rabbits fed a diet contaning 0.5% lead subacetate for periods of up to 2 years. Groups of pigment epithelial cells became congested with a lipofuscin pigment which was apparently derived from phagosomes of rod outer segments. Lipofuscin granules displaced melanin granules from the apical surface of the retinal pigment epithelial cells and resulted in conspicuous brown pigmentation of these cells in albino animals. Migration of macrophages and pigment epithelial cells into the subretinal space was common in affected areas. This pathology was not observed in the pigment epithelium of the ora serrata, or ciliary body. At the latest time periods, the abnormal lipofuscin pigmentation subsided, and degeneration of photoreceptors occurred. The pathogenesis of the lesions is discussed.