Ophthalmoscopic and Pathologic Studies of Retinal Degeneration in the Rats

Abstract

Ophthalmoscopic and pathologic examinations were carried out on 832 eyes of 416 male and female aging Fischer 344 rats. Various spontaneous ocular lesions were observed in rats of both sexes between 83 and 109 weeks of age by ophthalmoscopic examination. Spontaneous retinal degeneration occurred in 2.4% of male and 2.5% of female rats. The retinal degenerations were characterized by loss of the photoreceptor layer and microcystoid degeneration in the inner nuclear layer. Retinal lesions associated with cataract were examined in comparison with spontaneous retinal degeneration. The loss of the photoreceptor layer, cystoid degeneration, folding, proliferation of the pigment epithelium and gliosis were observed in the retina of rats with cataract. There were also various changes in the sclera and atrophy of the optic nerve.

The number of the photoreceptor cells and thickness of the photoreceptor layer gradually decreased with advance in age. There was a close relation between spontaneously occurring retinal degeneration in Fischer 344 rats and aging of the animals.