Time course of spontaneous ocular lesions of Crl:CD(SD) rats during 26 weeks rearing

Abstract

We examined the frequency and time course change of spontaneous ocular lesions in Crl:CD(SD) rats (90 males and 90 females) by serial ophthalmological examination from 5 to 31 weeks of age. In addition, we performed autopsy at 32 weeks of age and carried out histopathological examination of the eyeball (including the optic nerve).

Persistent hyaloid artery, vitreous hemorrhage and retinal red patch/spot were observed at 5 weeks old by ophthalmological examination, but these changes disappeared with aging. Persistent hyperplastic primary vitreous and persistent pupillary membrane were observed in 5 weeks old rats, and these changes disappeared in some rats but not in other rats until 31 weeks old. Focal opacity in lens (nucleus, anterior cortex) and hyperreflectivity in fundus increased with aging. Focal opacity in lens (posterior cortex, anterior and posterior capsule), iris hemorrhage, fixed pupil (the weak reaction of the iris by mydriatic) and vitreous opacity were observed infrequently. These findings were reversible. Diffuse opacity in posterior capsule of the lens did not disappear during the observation period. Calcification of the cornea epithelium, deposit of brown pigment of the ciliary body, persistent hyperplastic primary vitreous, retinal atrophy and retinal fold/rosette were observed by histopathological examination of the eyeball (including the optic nerve). It was difficult to histopathologically detect the focal opacity in lens.

In conclusion, serial observation of ocular lesions in each animal clarified several changes which increase with aging, occur at young age but disappear with aging, or do not disappear with aging.