Abstract
In the toxicity studies detection of ocular toxicity, ophthalmological examinations are carried out to select suitable animals for the studies during the quarantine period. During this period, spontaneous abnormalities are observed. In this report, we focus on fundus hemorrhage of these abnormalities in Fischer 344 (F344) and Sprague-Dawley (SD) rats and report them with prognosis.
On ophthalmological examinations in F344 rats at 5 weeks of age, spotty hemorrhage in fundus was observed in 5 of 249 males and 1 of 249 females, and flame-shaped hemorrhage in fundus was observed in 1 of 249 males. Of the spotty hemorrhage, 4 males showed band-shaped hyperreflective fundus with fundus hemorrhage. One female and 2 males with spotty hemorrhage at 5 weeks of age had diffused hyperreflective fundus at 9 or 13 weeks of age. Another male with the flame-shaped hemorrhage at 5 weeks of age had dark-red foci on hemorrhage area at 10 weeks of age but abnormalities including dark-red foci were not observed at 12 weeks of age. On ophthalmological examinations in SD rats at 4 weeks of age, spotty hemorrhage with band-shaped hyperreflective fundus was observed in 1 of 441 females. On the other hand, 1 in 441 male had a ring hemorrhage centering on the retinal artery at 4 weeks of age, and this ring hemorrhage was not found and hyperreflective fundus was observed on the same area at 16 weeks of age. In histopathological examination for diffused hyperreflective fundus at 11 or 13 weeks of age in 2 F344 rats, the inner nuclear, inner plexiform and ganglionic cell layers was thin or not present.
Based on these findings, it was suggested that there were relationships between spotty hemorrhage and hyperrefl ective fundus. In the cases of diffuse hyperrefl ective fundus, atrophic change of inner nuclear layer to ganglion cell layer were indicated histopathologically.
