Retinal degeneration in experimental Creutzfeldt-Jakob disease

Mice with experimental Creutzfeldt-Jakob disease (CJD) develop a progressive retinal degeneration after a prolonged incubation period. Sections of the eyes stained with hematoxylin and eosin revealed pathologic changes in the optic nerve and a marked degeneration of photoreceptor cell inner and outer segment areas. Both peripheral and central retina, normally 10 cells thick, were reduced to one photoreceptor cell or less in thickness. Ultrastructural analysis revealed total loss of outer segment and most inner segment elements. Only Muller cell microvilli and macrophages remained in the subretinal space. Macrophages were also visible in the remnant photoreceptor cell layer. The inner nuclear layer and pigment epithelial cell layer appeared normal. Muller cell hypertrophy was evident but was not accompanied by spongiform vacuolation. Several of the degenerative changes of the eye in mice with experimental Creutzfeldt-Jakob disease differ from those observed for scrapie in rodents. The pathologic similarities between the retinal degenerations occurring in mice with experimental Creutzfeldt-Jakob disease and those found in some forms of human retinal degeneration are provocative. These similarities raise the question whether or not other retinal degenerative diseases might be caused by infectious agents such as prions or slow viruses.